‘Physiological and Physical Science’ Writings, 1700’s


THE PRINCIPLES

of

PHYSIOLOGICAL AND PHYSICAL

SCIENCE;

COMPREHENDING THE ENDS FOR WHICH

Beings

WERE CREATED ;

and, 

AN EXAMINATION

OF THE

UNNATURAL AND ARTIFICIAL 

SYSTEMS

OF

PHILOSOPHY

WHICH NOW PREVAIL.

INTRODUCTION

NOTWITHSTANDING the boasted assertions

which are generally made, of the high degree

of perfection which, in these latter days, the

different branches of philosophy are supposed

to have attained it will, I fear, upon a fair

inquiry be found, that we continue in the very

infancy of our knowledge ; that, with the exception

of mathematical truths, and of those

arts which are founded on mathematical principles,

there subsists scarcely one subject,

either of physics, of metaphysics, or of physiology,

the science of which is clearly understood,

or, as to the truth of which an uniformity

of opinion subsists. The essential attributes

which different bodies possess, the first

and most simple elements of which they are

composed and the definitions by which those

elements are characterised, continue, to natural

philosophers, points ofconstant controversy and

disputation.

If we extend our views from the primary and

essential, to the secondary and accidental

qualities of matter, the last and most trifling

branch of natural philosophy, to which the

province of chemistry more especially beX*

INTRODUCTION.

longs ; we shall find, that although chemistry

has occupied the thoughts of, and been pursued,

with zeal the most ardent, by a great number

of learned and enlightened men in every

part of Europe, we, continue completely ignorant

of the principles on which chemistry, as a

science, is founded.

Without previous design, or by mere chance,

as it may be called, we have, it is true, discovered,

that when different substances, (such as

acids and alkalies, for example) are brought into

contact, an union between them takes place ;

we are by experience taught, that different bodies

have a stronger disposition to unite together,

to the exclusion of others with which they

may have been combined ; but of the cause

why these separations are produced, and new

combinations formed on what principle the

doctrine of elective attraction, or chemical affinity

is founded, wre are totally ignorant.

By the Researches of Professor DAVY, in the

art of chemistry, a multitude of opinions, which

by chemists had been received as fundamental

truths, have been overturned and exposed : he

has proved that a great proportion of the chemical

knowledge, not only of former times, but^

of the present day, is erroneous in some of its

most essential points; and it is now become a

common observation among our best chemists,

that in consequence of these new discoINTRODUCTION.

XI

veries, chemists will be probably obliged to

trace back the road of error which they have so

long traversed, in order to learn afresh the first

principles of their art/*

It is greatly to be lamented that the pursuits

of the chemists, instead of being confined to

their proper objects to the examination of the

qualities of matter, dead and common have

been equally, but improperly, directed and extended

to the investigation of living matter also ;

hoping to explore the causes of animation, and

of vital action, from chemical phenomena, which

are the inevitable attributes of decomposition

and decay.*

* The Monthly Magazine, some time since, very justly

observed,

” that Dr. DAVY’S Chemical Lectures shew, that

students in chemistry have to unlearn most of what they have

received as authority in that science. It may be hoped, therefore,

that we shall have no other voluminous systems of this

variable science> till its elementary principles are somewhat

better settled

* In deprecating, as I do, experiments, it is proper that I

should be clearly understood. I deprecate the application of

chemistry to physiology, as much as I would deprecate the

practice of employing the phenomena of death,^in order to

explain the actions of life ; and more especially I deprecate

the experiments made on different organs and fluids of the

living system, because the natural and healthy functions of a

part can never be ascertained through the medium of mutilation,

or extirpation; but%ith respect to the investigation of

matter dead and common, experiment alone is the medium

Xl INTRODUCTION.

It has been with this vain expectation, that

every solid and fluid, of which vegetables and

animals are composed, have been analysed with

the most accurate nicety; and effects, which

altogether depend on vitality and animation,

have been attempted to be explained, from the

result of decomposition and of death. To this

total inversion of all principle, with respect to

the relation which exists between things external

to the animated system, and the animated

system itself is to be ascribed the absolute

ignorance which prevails, not only of the function

of digestion, but of the operation of medicine

also ; not only of every organ, but of every

fluid of which the system is composed, Until

physiologists be made to feel that physiology is

still an art, not a science ; and pathologists,

that the practice of medicine is altogether empirical

; until the state of error and of ignorance

which exists, be truly and fairly represented, I

see no hope whatever of improvement, or of

reformation.

Much as there is to deplore with respect to

the application of physiology to practice, it is

through which its properties and attributes can be attained.

I think it proper to give this explanation, in order that it may

not be objected to me, that I reprobate experimental philosophy

in general, the odium of which, I am persuaded, would

otherwise be attempted to be fixed on me.

INTRODUCTION. X11I

sas a feather in the balance, when compared

with the relation which it is supposed to bear

to metaphysics. Instead of tracing the relation

which the different organs bear to each

other, as the means that are employed, with a

view to ends ; instead of exploring the nature

of life, and more especially of intellect, or of

soul, of that principle, by which man is more

especially characterised, from every other animal,

and by the proper exercise of which, he

is able to abstract himself from matter, and

from sense ; it is to the attributes of matter

alone, impelled by sensible objects, that the

existence f mind is generally ascribed ; and

by which the doctrine of materialism, in its

fullest extent, is attempted to be established.

Although the doctrine of materialism is not

proclaimed in our philosophical schools in

word, I will maintain, that it is so in deed.

I will maintain, that the existence of any

immaterial, or spiritual principle, is seldom,

if ever, mentioned, much less employed,

as constituting the cause of organisation,

or of intellection ; on the contrary, that

it is to the organisation alone, and to the

matter of which that organisation is composed,

that the principle of life and of mind, as

effects, is immediately referred. This evil

spirit, if it dared, would even manifest itself

XIV INTRODUCTION.

within the bosom of our universities. About

one year since, two members belonging to one

^>f the principal colleges in Oxford, published

a book, entitled,

” The Necessity of Atheism”

and they even had the audacity to attempt a

defence of the principles it contained, before

a convocation appointed to examine them.

These misguided men have been very pro-

-perly expelled the university, and the wretched

trash which they had written has been suppressed.

*

It has been the object of my most particular

solicitude to expose the errors of such

pursuits, and to point out the evils to which

they lead ; to show that such a system, instead

of leading to truth, not only recedes from it,

but perpetuates, and establishes, what is infinitely

worse than ignorance erroneous principles

: that instead of exploring the essential

properties of matter, with relation to the system

of order and subordination which exists

throughout the whole system of nature, se-

‘* I think it proper to mention this fact as an illustration*

more than as a proof, of the truth of my assertions. Whatever

blame might formerly be imputed to the laxity of University

morals, or University discipline, has been done away ;

there can be no cause of complaint now, the present system of

education bids fair to answer the ends for which it was originally

designed.

INTRODUCTION. XV

condary qualities alone obtained by artificial

means, are the objects of our present inquiries.

Instead of contemplating the attributes of the

Creator, from the works of creation, it is

through the medium of unnatural phenomena

alone, that natural phenomena are attempted

to be explained, I complain that the present

system of what is called philosophy, is an artificial,

not a natural one; and that the very

first dictum, or aphorism, proclaimed by LORD

BACON, in his NOVUM ORGANUM, is altogether

violated by our philosophers.

” Homo

Naturae minister et interpres, tanturn facit &

intelligit, quantum de naturae ordine, re vel

mente observaverit; nee amplius scit aut potest.”

I complain, that instead of making (as true

philosophy must ever tend to do,) man religious,

the present system is at variance with

religion, and deprives him of the benefits, and

of the comforts which religion is calculated to

bestow : that instead of leading man to God,

it estranges God from man, and separates, to

the utmost possible distance, (if I may be

allowed the expression,) the soul from the

Deity.

The Chapter which treats of Organic Life,

or the means by which the ends of existence

are attained, is, for the most part, a Syllabus

XVI INTRODUCTION.

of my NEW SYSTEM of PHYSIOWDGY,* which

was published in the year 1798.

* This work was first written with a view of exposing the folly

and errors of the Brunonian doctrine, which was, at that time,

in this country, as it still continues to be over different parts of

the continent, in general estimation. It is not likely that

any system of physiology, which took for its principle the

power of life, and the aptitude of matter which traced the

phenomena of vitality from organisation to action, and investigated

the particular organs, as the instruments by which

ends were obtained, would be very well received by those who

begin with death, and who end with life. Notwithstanding the

new opinions which it proclaimed, it was generally well spoken

of; and by the Medical and Chirurgical Review in particular,

it was observed,

” that in the execution of the extensive work

before us, Mr. SAUMAREZ is, in many parts, original ; it is,

however, but justice to add, that a passion for novelty does

not appear to have led him to a hasty adoption of opinions on

slight or trivial grounds. His arguments are, in general,

well supported, arid his conclusions cautiously deduced. As

a whole, it certainly bespeaks the industry and genius of a

writer who dares to think for himself, unfettered by prejudice

and authority, &c.” Again,

” we are not sorry to see the

errors of the Brunonian system thus combated by an able

champion ; it happens with this theory, more than with any

former one, that its errors are not merely speculative, but

lead to the greatest possible mistakes. Indeed it would be

no easy matter to calculate the mischief which it has occasioned

in the hands of young and inexperienced practitioners ;

but when we find, from Dr. BEDDOES himself, the translator,

its ascendency over men’s minds, in different parts of

Europe ; and that in the celebrated University of Pavia, there

is hardly a student endowed with talents, who is not a Brunonian,

it is surely high time to examine its principles and refute

its errors, &c. &c.

fr \ F^ S? )

CHAPTER I. ,> $ /

(\\ IVukV

ON THE PRINCIPLES OF SCIENCE.

IT is not my present intention to give an historical

detail of the rise and progress of scientific

knowledge, from the more remote periods of

antiquity, to its decline and fall during the

space of more than one thousand years, appropriately

denominated the dark ages. Knowledge

(if knowledge it may be called) was then

confined to the schoolmen ; the erroneous

practice, general at that period, of reasoning

without facts, and of drawing conclusions from

false principles, became at length apparent to that

great luminary of our country, LORD BACON.

The accumulation of error was, at that time,

too extensive to be corrected by any individual,

however mighty in intellect. Instead of unravelling

the gordian knot, he cut it. He did

not amuse himself with solving the most absurd

and ridiculous propositions that can be conceived

; with calculating, for example, how

2 PRINCIPLES OF SCIENCE.

many millions of angels could dance upon the

point of a needle ; but he determined to accumulate

facts only, before he generalised them ;

and thus was the art of induction raised upon

the ruins of false syllogism.

It is greatly to be deplored, that the plan

which he himself pursued, has not been adhered

to, by his followers in general ; and that attention

is not so much paid to the simple observation

of natural phenomena, as to those which

are the result of sophisticated experiments. I

do not decry experiments in general, it is the

abuse, not the use of them, which I reprobate

and condemn. It is through the agency of experiment,

that the useful arts have obtained so

high a degree of elegance and perfection ; that

chemistry, and what is called experimental

philosophy in general, are in a constant state of

improvement ; and that the certainty of many

uncertain things is ascertained. Let it not,

however, be supposed, it is on the result of experiment

alone that the whole of our knowledge

depends, or that it was so considered by Lord

Bacon himself; he expressly states that natural

history is the result of simple observation, and

classes it before experimental history. He considered

it the first means which ought to be employed

to accomplish the renovation, or, more

correctly speaking, the grand instauration of

science, as he terms it, which he had in view.

PRINCIPLES OF SCIENCE.

Had he been desirous of appealing to experiment

alone, he would have excluded the facts

which are the result of simple observation only.

If such had been his principles of learning, it

would have led, (as it has been well observed,)

to the unwarrantable length of supposing, that

knowledge could only be obtained through an

artificial, rather than through ^natural channel.

Assisted by the furnace and the crucible in the

laboratory, we should have been forced not to

use our eyes, unless with a candle in our hands

and spectacles on our nose and to withdraw

our senses from the knowledge which they convey

to the mind, of the undisturbed appearances

of nature.

Instead, however, of appealing to simple observation

for the apprehension of natural phenomena,

few phenomena are, at this time, supposed

or admitted to be true, unless proved by

the test of experiment ; unnatural effects are

generally preferred to those which are natural

and unsophisticated. The phenomena of dis.

ease are adduced to explain the actions of

health ; the chemical changes which dead and

common matter undergo, are often assumed to

account for the causes and phenomena of life.

To the late MR. J. HUNTER, to DR. GOODWIN,

SPALLANZANI, and a few others, we are

eminently indebted for many valuable facts obtained

through the medium of experiments per4

PRINCIPLES OF SCIENCE.

formed on living animals : these facts acquire

their intrinsic worth, from their exposing to our

view, internal operations which were before

concealed; thereby manifesting the natural

condition of things without altering it.

Cruel and horrible as these experiments were,

if they cannot be justified, it is hoped that they

will find considerable palliation, in the motive

which led to the execution of them ; the earnest

hope which a few of these gentlemen entertained,

of bringing light out of darkness, and

that the sufferings of the brute might ultimately

prove beneficial to man. Although humanity

feels a pang at the recollection of such pursuits,

they ought nevertheless to be tolerated to

a certain degree, when performed by those who,

having an end in view, are anxious to prove, by

the fact of experiment, the truth or error of the

principles of physiological science, entertained

by them.

For that numerous class of pretenders to physiology,

for those minnows in science, who

without end or design, are impelled, by blind

chance and mere curiosity, to inflict the most

barbarous cruelties on cold and warm blooded

animals, there is no excuse ; any more than for

those, who mutilate and extirpate different organs

from the living system, in order to ascertain

the natural functions which those organs

are intended to perform, and the use which

PRINCIPLES Otf SCIENCE.

they are designed to subserve. The merit of

many of these gentlemen, in other points, is not

meant to be depreciated ; it is in many respects

entitled to praise. When some of them, however,

arrogate to themselves the claim of furnishing

to the world all the physiological knowledge

in it, and, as if alone qualified to discuss a

physiological question, receive with slight, and

consider as mere drivellers those who take

natural rather than artificial phenomena, and

whom they contemptuously denominate closet

philosophers, we cannot but feel amused with

the folly of such conceits.

In order to appreciate the whole merit to

which they are entitled, it ought to be examined

; and I am persuaded it will be found that

the reason of this conceit and pride arises in

consequence of mistaking art for science, the

man who carries the hod, for the architect who

designs, and, from confounding the laborer

and bellows-blower with the physiologist and

metaphysician.* I do not include the mail

* It is not to be supposed, that I am singular in this opinion

; it is the opinion of some of our best experimentalists

also. I shall quote a passage from Dr. Enfield, the learned

Professor of Natural Philosophy at the establishment or university

of Warrington ; it is contained in the preface of his

celebrated work, intitled the Institutes of Natural Philosophy;

and dedicated to Dr. PRIESTLEY. After recommending

a knowledge of mathematics, he observes, that,

” a mechanic

6 PRINCIPLES OF SCIENCE.

who from a superiority of intellect, possessing

a knowledge of cause, foresees and foreknows

the effects which will inevitably follow, and is

anxious to put his science to the test, and to

prove its truth by experiment : a philosopher,

such as this, is seldem qualified for the task of

performing it, he rather delegates the execution

of it to others, than performs it himself. What

qualifications, I would ask, are requisite for the

experimentalist in chemistry ? There is not, I

am persuaded, an experienced artist in any of

our manufactories, who is not able to mix the

different ingredients intended to be employed,

who would set about making a machine without the requisite

tools, would not act more absurdly, than a student who would

attempt to understand the science of natural philosophy, without

those helps. A preceptor, who professes to teach this

science in the easy and amusing method of experiment alone,

is an architect without his rule, plumb-line, and compasses.

Facts are, it is true, the materials of science; and much praise

is unquestionably due to those, who have increased the public

store by new experiments accurately made, and faithfully

related. But it is not in the mere knowledge, nor even in the

discovery of facts, that philosophy consists. One, who proceeds

thus far, is an experimentalist ; but he alone, who by

examining the nature, and observing the relation of facts, arrives

at general truths, is a philosopher : a moderate share of

industry may suffice for the former ; patient attention, deep

reflection, and acute penetration, are necessary for the latter.

It is therefore no wonder that amongst many experimentaUstt,

there should be few philosophers

PRINCIPLES OF SCIENCE. 7

to blow the bellows, and even to decide on

the result that ensues, as well as the best

chemist that has ever existed.

The same limited means are alone wanting in

physiology. There is not a lad of twenty years

of age, who comes from the country to any of

our hospitals in town, and who, after passing

with common industry two seasons in any of

our anatomical schools, is not perfectly competent

to perform any physiological experiment.

In addition to a precise knowledge of

position, the only requisites wanting, are a

steady hand, a sharp knife, a tolerably good

pair of eyes, and an unfeeling heart.

To rip open the flanks of a dog, as well as of

a calf, to drag any particular organ out of its

situation, to paw and to squeeze it, to decide

whether it swells or contracts, whether it causes

pressure or not, on surrounding parts ; to tie a

ligature upon the vessels or tubes, with which

any organ is supplied; or, to extirpate the

organ altogether, and finally cut the animal’s

throat, and strip the skin for the sake of the

leather, can be performed, as perfectly, by any

carcase-butcher in any slaughter house, as by

the generality of physiologists.*

* To free myself from the charge of exaggeration, and to

enable the reader to decide for himself, how far I am justified

in saying that the degrees of talent necessary to perform an

8 PRINCIPLES OF SCIENCE.

Men, such as these, however qualified they

may be to act well, seldom think correctly.

experiment are very trifling, and that it it generally done with

a degree of cold-blooded apathy which is shocking to humanity,

I shall relate a few, among a multitude of similar experiments,

that were made on living dogs, in order to ascertain

the change of color which the blood underwent, during the

process of respiration.

” I procured several large dogs,” says

one of these gentlemen,

” and after removing the sternum or

breast bone of each, and exposing to view the trunks of the

pulmonary arteries and veins, &c. &c.” But another, and he,

by far the most eminent of all, after going through the preliminary

operation of cutting the parietes of the thorax, and

sawing the ribs, and exposing to view the organs which it contains,

says,

” I have repeated this experiment several times

upon several animals, and commonly for half an hour at a

time ; which was sufficient to allow me to make my observations

with coolness and accuracy ; it was curious to see in the

first part of the experiment, the coronary arteries turn darker

and darker ; but on blowing air into the lungs, the blood gradually

resumed the florid red. 1 cut and sliced off a piece

from the lungs, and found that the colour of the blood which

came from the wound, corresponded with the above effect,”

&c. &c.

I should not have dwelt upon this subject, had I not known

that the practice of torturing animals among young men is

become, of late, very much the fashion. Such are the tender

mercies which they have for themselves, that to take away

from the poor creatures the only consolation left them, the

power of expressing, by their cries, the anguish which they

suffer ; they first begin by cutting and dividing the recurrent

branch of the parvagum, which subserves to the motion of the

tongue and lower jaw, and, by that means, prevent the animal

from howling.

PRINCIPLES OF SCIENCE. 9

Were we to descend to particulars, it could

easily be proved, that the premises which they

assume, consisting, for the most part, of the

mutilated and unnatural condition of things,

can seldom convey to the mind data, fit for

physiological science ; that the conclusions

which they draw, however true they may be

from the principles which they assume, are

most erroneous in themselves, so far as relates

to the thing which they are intended to explain.

This piece of humanity is exactly analogous to that posessed

by Santerre during the maisacres in Paris, in the early part

of the French revolution. At that time he was commanding

officer of the national guard, and it was in his power, had he

possessed the inclination, to have prevented a multitude of

persons from being sacrificed: during this period, however he

remained quietly at table, while innocent blood flowed in torrents.

One of his satellites, by accident, put his foot on the

tail of a little dog situated under the table, which occasioned

the dog to squeak ; Santerre, in great agony, reproached v, ith

bitterness the inhumanity and cruelty of the fellow who caused

the sufferings of the poor animal. I cannot avoid lamenting,

more especially, that in many of the popular lectures which

are given in different public and private institutions, in this

country, that ladies sit with composure, to see the sciatic

nerves of frogs stripped of the surrounding flesh, and by

means of the Galvanic fire, the animal thrown into the most

dreadful convulsions : to behold different animals poisoned

by means of different mephitic gases ; or, by placing them

under the receiver of an air-pump, and exhausting the air out

of it, to observe, with indifference, the infliction ofa languishing

and lingering dath.

10 PRINCIPLES OF SCIENCE.

The system of induction introduced by Lord

Bacon, had not for its end, as many of his unworthy

followers have supposed, the mere abstract

accumulation of facts. Facts, isolated

and unconnected, resemble the rough materials

intended for the foundation of a magnificent

edifice. The carpenter who chips the timber,

and the mason who polishes the marble, are not

to be considered as the men of science ; but he

alone, who, from a precise knowledge of principles

and of causes, is able to direct those

materials to be arranged with order, form, and

symmetry. It was with that end in view, that

his lordship analysed before he generalised;

that he has separated the individual from the

species; the species from the genus ; and, from

a multitude of effects, endeavoured to arrive at

cause.

Had his lordship limited his views to induction

only, or had he cherished a hope, that

through a multitude of forced and unnatural

effects, he would ever have been able to establish

true principles of science; instead of being

the father of philosophy, as he has been called,

he would have been its greatest enemy.

In the analysis of facts which are intended

to constitute the principles of any science, it is

of the first importance, that none should be admitted

but such as are scientifically efficient of

the conclusion, so that the effect produced,

PRINCIPLES OF SCIENCE. 1 1

shall always correspond to the nature of the

producing cause ; that we should separate

partial from general facts, accidental and transient

attributes from those that are permanent

and essential. It is by a process, such as this,

that we become possessed of those individual

facts which form the base and the source of

every science, the immediate and proximate

cause whence effects are derived : it is by the

enumeration of these attributes, which, always

abiding in the subject to which they belong,

apply universally to every individual of the

species, characterise its nature, and distinguish

it from a body belonging to every other class.

Without the full possession of these permanent

and universal facts, a general, not a particular

knowledge of any subject can ever be obtained :

without history, we can never have definition ;

and without axiom, there can be no science.

It is on principles such as these, of selfevident

truth, that the whole of mathematical

science is founded, as well as every other

branch which deserves the name of science.

Without the possession of these first principles,

it has ever appeared to me impossible, that we

can obtain any science of the phenomena which

are produced ; without them, a general, not a

particular knowledge may be acquired; we

may become historians, but not philosophers ;

good artists, but not men of science. Know12

PRINCIPLES OF SCIENCE.

ledge, properly so called, does not simply consist

in the impressions made on the senses by

the operations of external phenomena ; true

knowledge can only be admitted to exist, when

we are in full possession of the cause whence

the effects are derived ; and he alone can be

denominated the man of science, who is able to

connect the cause with the effect.

These principles are not only more powerful

and true than the thing produced, but the actual

cause of its production : they possess the

power of imparting their own efficacy and

energy to the bodies on which they operate, and

they constitute the cause whence secondary

effects are made to flow: by which, the principle

of life, for example, resident in the semina of

plants, or in the ova of animals, is enabled to

act on matter dead and common, and to convert

it to a living state ; by which, the sun, as the

principle and fountain of light, becomes the primary

cause of illumination in general; by which,

the expansibility of air is enabled to excite motion

in matter, passive and inert. Many men,

who have not learned the principles of particular

sciences, can frequently assign reasons,

or the cause why, for the effects which they

behold ; they seem, intuitively, to possess a degree

of science, and to attain rules by chance,

which instruction is especially designed to unfold.

Mr. HARRIS, therefore, very accurately

PRINCIPLES OF SCIENCE. 13

observes, that in the investigation of principles,

we are first taught to learn that every science,

as arithmetic, geometry, music, astronomy, &c.

may be resolved into its theorem, every theorem

into its syllogism, every syllogism into its

proposition, and every proposition into certain

simple or single terms.

If we were to begin the discussion of any

branch of science before we had attained a

knowledge of simple terms, which are in themselves

irresolvable, it is evident that we should

begin in the middle ; and, if we were to begin

at the theorem itself, before we had attained

a precise knowledge of a syllogism, and of a

proposition, we should begin not merely at the

middle, but at the very end. Simple terms,

therefore, constitute the base, the punclum

saliens, whence all scientific knowledge ought

to commence ; to begin from other data, not

only leads to hypothesis, but is an inverted

order of learning.

It is by the previous attainment of this simple

knowledge, that we become qualified to

learn the connecting media, of which the most

compound knowledge is formed, and that the

extreme parts, the beginning and the end are

united, so as to compose one whole. It is in

this investigation that the office of science consists

; and forms the true object of its pursuit.

Science, therefore, begins from principles, and

14 PRINCIPLES OF SCIENCE.

proceeds through proper media to the conclusion;

from cause to effect, from things

general and universal, to things particular and

accidental.

This power of the mind to learn, and to be

instructed, is termed, by Mr. Harris, natural

capacity, and is an attribute common to all

men ; the superior facility of being taught,

which some possess above others, is called

genius; the first transition, or advances, from

natural capacity, is called proficiency, and the

end, or completion of proficiency, habit: if

such habit be conversant about matter purely

speculative, it is called science; if it descend

from speculation to practice, it is termed art ;

and, if such practice be conversant in regulating

the passions, it is called moral virtue. Before

the habit of moral virtue can be attained, there

are many appetites to be curbed, various propensities

to be corrected, and many temptations

to be resisted.

Although it is unquestionably true, that

there exist different sciences that may be said

to belong to one and the same genus, in

which the principles of the one may be legitimately

transferred to the other, it is, nevertheless,

very seldom the case. Principles of science

do not emigrate, as migratory birds at

different seasons, to different countries ; individual

sciences, for the most part, have their

PRINCIPLES OF SCIENCE, 5

own facts, and their own principles. The conduct

of those who take false analogies for the

explanation of the same phenomena, or the

principles of dissimilar sciences, to account for

the effects produced in those to which they

have no relation, cannot be too strongly reprobated

and condemned.

If the mere capacity appertaining to different

species of common matter, or even the chemical

power which it may be supposed to possess,

were employed, as it too often is, to account

for the cause of vitality ; if the principles

of hydraulics were employed to account for the

motion of the fluids in the animated system ;

or those of pneumatics for the process of respiration

; in short, if the principles of chemical

science were advanced to prove the nature of

vital action in general, and of ratiocination in

particular ; facts, or principles, such as these,

would unquestionably be false. The same

conclusions may be drawn if the principle of

vitality in plants were adduced to prove the

principle of instinct in brutes ; or the principle

of instinct in brutes employed to ascertain the

nature of intellect in man. These facts having

no reference whatever to the particular subject

which they were intended to demonstrate, and

being, in themselves, inefficient and defective to

prove the conclusion, must ever be considered

as false. The principle of intellect in man can16

PRINCIPLES OF SCIENCE,

not be proved by the nature of brutal instine^,

any more than the vitality of plants can be

proved from the chemical properties of matter,

dead and common: in this case, physiology

and physics, chemistry and metaphysics, would

be confounded together.

The same observations may be matfe, if the

facts which appertain to vision, were employed

to account for the cause of hearing, or of those

which appertain to taste, with those which belong

to the olfactory sense.

ilf we proceed from physiological to mechanical

sciences, the same remarks will be equally

applicable. If the principles of hydraulics

were employed to account for the effects produced

in pneumatics ; and, even if those of

pneumatics were advanced to prove the nature

of optics, such facts would be false ; as false,

as if we were to confound the facts which appertain

to time, with those that belong to place ;

figures with lines, and lines with figures ; and,

attempt to prove magnitude by numbers, or

numbers by magnitude; and confound geometry

and arithmetic together. For the express purpose

of guarding against this great error, it

would seem, that Sir ISAAC NEWTON, in his universal

arithmetic, praises the antients for not

deducing geometrical conclusions from arithmetical

principles, and for not confounding geometry

and arithmetic together.

” Each of these

PRINCIPLES OP SCIENCE. 17

sciences,” says he,

possessing principles peculiar

to itself, and distinct from other sciences.”

What other construction can these words bear,

than that he who employs the primary and permanent

facts which constitute the principles, or

the axioms (as I may call them) of every individual

science, in order to account for the

effects produced by the power of the facts, or

principles, belonging to another, between which

there is no analogy whatever takesfalsefads

for his data. False facts may, therefore, be

considered as facts which are assumed for false

principles ; or, false causes, to which effects are

improperly referred : the phrase, by the driveller,

will either be misunderstood, or be considered

as an absurdity ; by the ignorant in

science, as contrary to appearances, but not

an absolute contradiction ; as a paradox, but

not a nonentity;* by the man of real science,

the phrase will be admitted as legitimate and appropriate,

and be, by him, constantly appealed

to, as the true and primary cause of error. He

will ascribe to false facts, the mass of false

* There is an evident difference between a paradox and a

contradiction. Both, indeed, consist of two distinct propositions,

and so far only are they alike ; for, of the two parts

of a contradiction, the one or the other must, necessarily, be

false ; of a paradox, both are often true, and yet when

proved to be true, may continue paradoxical that is, contrary

to general appearance.

C

IB PRINCIPLES OF SCIENCE.

philosophy which continues to prevail at

day. I have, perhaps, dwelt longer on this

subject than was necessary ; I was, however,

led to it in consequence of the complete ignorance

which it appeared to be involved in, by

those who ought, from their situation, to have

been better instructed and informed ; the idea

of false facts was not only decried by them,

but even attempted to be ridiculed.

Having endeavoured to show what true principles

are, and what false principles are not ;

I shall now proceed to point out the errors of

taking false analogies as principles of science,.

Wherever a uniformity of nature and of character

exists between different bodies, analogy

becomes a legitimate source of induction; it is

from the analogy which subsists between the

phenomena of life and health, of disease and

death in plants, that these may often be employed

to illustrate the correspondent changes

which take place in brutes, as well as in the

human species. Analogy becomes also a legitimate

source of induction, when a similarity of

nature exists between bodies whose functions

are the same, however dissimilar they may be

in structure and appearance. By analogy we

predicate the same attributes to thegills of fish,

as we do to the lungs of the mammalia ; to the

ovaries of a sprat or of a whale, as to the ovaries

of a rabbit, or of an elephant. And, it is

PRINCIPLES OF SCIENCE, W

because geometry defines many of the assumptions

and suppositions of the science of optics,

as well as of other sciences, that analogy between

them may often be admitted.

Analogy may be admitted throughout the

various species of common matter which exist,

whose nature and properties are the same, however

different in appearance they may be ; between

the capacity of a lump of clay, and of a

piece of flint; between the flexibility of lead

and of iron ; between the elasticity of steel and

of whalebone ; and between the expansibility

of gases in general, however different in other

attributes. The reason why analogy between

these different genera is admissible is, that

however different from each other their particular,

or secondary properties may be, they,

nevertheless, always continue to retain the

same generic character; that, although the

chemical characters of particular gases are

proved to be totally different from others, all

however are expansible. The same may be

said of elastic, and of flexible bodies.

To bodies such as these, Sir ISAAC NEWTON’S

second rule of philosophising may apply, that

” of natural effects of the same kind, the same

causes are to be assigned.” It must, however,

be very obvious, that this rule can never apply

to bodies whose nature and properties are

essentially different from each other, and bec2

20 PRINCIPLES OF SCIENCE.

tween which no analogy whatever exists. It is

not legitimate to make use of analogy between?

flexible and elastic, any more than between

elastic and expansible bodies ; much less between

matter which is ponderable and dark,

and such as is imponderable and luminous ;

between that which is passive and opake, and

that which is essentially active and transparent ;

between a cloud of dust, and the rays of light ;

between the natural obscurity of this globe of

earth, and the illumination and splendor of the

sun.

In order, therefore, to prosecute to a successful

termination, any branch of science, it is

of the utmost importance, that we should be in

full possession of the first principles, on which

that science depends ; subsisting as causes

from whence the effects proceed ; and that the

definitions we employ, should be determinate

and precise, expressive of the thing signified.

This previous and antecedent knowledge, not

only comprehends a knowledge of the nature of

the subject itself, and of the terms by which its

existence is known and understood, but also

the various attributes belonging to it; the

nature of which will form the subject of the next

chapter.

ON THE ESSENTIAL PROPERTIES OF MATTER

WITH RELATION TO VITALITY.

THE attributes which different bodies possess,

may be divided into two classes ; into those

that are inherent, or essential, and into those

that are accidental and derived; into such as

are resident within the body originally, and are

inseparable from it ; and into such as are produced

by the action of external influence upon

  1. When a body acts independently of external

influence, the action produced constitutes the

true test, by which a knowledge of its nature,

is to be obtained : on the contrary, when a body

acquires properties by the agency of an external

cause, the creation of those properties, may be

considered as constituting the vast tribe of

accidents in bodies, as they have been called by

some, and of secondary qualities by others, and

which are obvious and perceptible to our senses.

22 PROPERTIES OF MATTER

If the nature of each be considered, the

will be found very different from the other ; it

is not by the transient and accidental color of

the skin, which different beings possess, whether

that color be pallid or red, that the human

species, in general, is characterised. The external

color may be imitated by art, upon -a

lump of clay, or a block of wood ; upon a dead,

almost as perfectly, as on a living subject;

these qualities, therefore, may be considered as

secondary, or accidental. It is, on the contrary,

to the more permanent and indelible

attribute of organisation, and of form of

action and of power, that animated beings

essentially possess, that every individual is

known to be what it really is, awd through

which it is distinguished from every thing else.

The same observations equally apply with

respect to the different species of common matter,

of which the world is composed ; although

each species possesses particular properties of its

own, which are different from others, and that

a variety of changes between them are perpetually

taking place : the most solid bodies are

cften liquified into a fluid, and subtilised into

vapor, that vapors are often condensed, or

consolidated into a liquid, and even a solid

form. In whatever form it may exist, every

particle of which it is composed, continues to

possess one attribute which is common to the

WITH RELATION TO VITALITY. 23

whole, and which is inseparable from it the

attribute of extension extension into lengthbreadth,

and thickness.

If we proceed frora this attribute universal,

to detail the attributes particular, which different

bodies obviously possess, we shall find

them to be totally different from each other ;

and that a great diversity of changes is constantly

taking place between them. To ascertain

the nature of these attributes, and the

relation which they bear to each other ; finally,

to trace the phenomena, 0r effects which are

produced, to their producing cause, constitute

the especial objects which physical science is

designed to explore, and the true pursuit of a

natural philosopher.

Among the first advances that were made

for the purpose of putting confusion into order,

<Jassifications of their various orders were formed

; the infinite multitude of individuals which

exist, were arranged under particular species ;

different species under particular genera ; to

which each individual could be easily referred,

according to its general character and mode of

subsistence.

It was with a view to this end, that the whole

of the material world has been commonly

classed, under three different orders, or kingdoms

; into animal, vegetable, and mineral. A

generalisation, such as this, appears tomehighly

24 PROPERTIES OF MATTER

objectionable, because extremely defective.

Instead of comprehending the whole, it excludes

a part, it excludes that immense and

indefinite portion of matter, which, instead of

being mined and immured within the bowels of

the earth, subsists, for the most part, out of it ;

it not only excludes water, and gaseous bodies

in general, but the whole planetary system in

particular. To supply this state of imperfection,

I shall class the whole system of nature,

as it has been called, and the matter of which

it is composed, under the three distinct heads,

of common, of living, and of dead matter.

FIRST, By living matter, I comprehend the

various orders of living beings with which the

universe is replenished and adorned.

SECONDLY, By dead matter, I confine myself

to the exuviae of animals, and of vegetables ; as

well as to the whole substance of which these

beings are composed, after the actions of life

are at an end, and the state which is known by

the appellation of death.

THIRDLY, By common matter, I mean the primitive,

or original materials, or elements, of

which the world is composed ; matter which

either, has never received the participation of

life, or having received, has lost it, and been resolved

back into a common state.

To physiology, belongs the province of investigating

the properties of living matter. To

WITH RELATION TO VITALITY. 25

physics, such as is dead, or common. Correspondent

to the difference of character which

subsists in matter dead, or common, whether

solid, liquid, or gaseous, a subdivision in the

science of physics is made. Geology refers to

the solid and’ common matter of which the

world is composed. Hydrology to liquid, and

meteorology, to that which subsists in a gaseous,

or aeriform state ; and finally, chemistry is designed

to examine, and to ascertain, the more

intimate and particular qualities, which each

substance possesses, and the changes it undergoes

by union and combination ; the means

employed are those of analysis and synthesis.

If we begin by examining the attributes of

common matter, in its form the most simple

and uncombined, we shall find that an increase

of bulk alone ensues, by the aggregation of its

parts ; and that if a union takes place between

bodies, whose qualities are different, both lose

by the combination some of the properties possessed,

separately, by each ; whether it be a

solid, or a fluid ; an alkali, or an acid ; a

metallic ore, or a gaseous fluid. If matter is

acted upon by some external agent, and motion

is produced ; the motion produced perpetually

diminishes, and is ultimately lost : the matter

impelled, gradually verges from the state of

activity into which it had ben excited, and

returns to the one in which it existed before,

#6 PROPERTIES OF MATTER

passive and inert. Whether, therefore, we con*

template the nature of common matter, at rest,

W in motion ; at unity, or in union ; whether

the changes it undergoes proceed from motion

mechanical, from mixture chemical, or from

both together, we shall find it a universal truth,

that the same effects, universally result froia

Jhe operation of the same causes.*

Ifwe extend our views to animated beings in

general, we shall find that the faculties and

powers so varied and wonderful which they

severally possess, prove that each system, not

only in the progress of its evolution, but in the

actions it performs, is governed and impelled

by laws, distinct and peculiar dependent on

the class to which it belongs ; and that the

matter itseJf, of which it is composed, is, in it$

attributes, totally different from common matter

in a passive state. In common matter, an increase

of bulk is invariably produced, in proportion

to the quantity of matter applied.^

* It has been owing to the uniformity in the effects which

common matter is found to describe, that rules have been

formed to which those effects correspond. These rules, by

some, are called Principles, by others, Laws. The rules of

Mechanics, illustrate and explain the operation of matter in

point of quantity ; of chemistry, in point of quality ; of geometry,

the quantity and degree of motion described.

t I allude, of course, to homogeneous matter only ; chemical

union often causes a condensation between the parts,

and a consequent diminution of volume.

WITH RELATION TO VITALITY. 27

In a living system, no addition of matter can

produce an increase, after it has attained the

full perfection of its evolution. The increase

of bulk in common matter, is derive^ by accretion

from without. In the living system, it

proceeds by a power of conversion, and of secretion

from within. In the one, the whole collected

mass is irregularly heaped up, rudis indigestaque

moles : in the other, the most exquisite

symmetry and order mark the arrangement and

disposition ofall its parts. Theformer is destitute

of all power of fabrication and restoration ; the

latter is endowed with both ; while common

matter, by its inertness, continues permanently

the same through the long course of revolving

years ; the latter, is in a state of perpetual mutation

and action ; and, after having attained its

period of perfection, perpetually verges to inevitable

decay.

If we proceed to examine the motions which

are excited in an inanimate machine, however

simple or complicated the construction of the

machinery may be, and compare them with the

mechanical actions that flow from the power of

a living system, the same contrariety will be

found to subsist. In a hydraulic machine, the

water is impelled by a vis a tergo alone from

without :; In a living system, the fluids are propelled

by a power from within, inherent in the

vessel by which the fluids are contained. In

28 PROPERTIES OF MATTER

the one, a Remora is caused by the friction of

the water upon the containing vessel ; in the

other, the power of the containing vessel is the

cause of the velocity in the fluids they convey.

In the former, the distribution is regular and

uniform ; in the latter, we constantly behold it

altogether different ; being often increased, or

diminished, throughout the same parts, at different

times. A mere blush in the face decidedly

proves, that, although vessels the most

extreme and minute, possess a power common

and concurrent with the vascular system at

large, they are, nevertheless, endowed with

an exclusive one also. In the former, the

water remains unaltered and unchanged ; in

the latter, the blood suffers a constant alteration

in its nature.

If the effects of the fluids upon the vessels of

both be examined, we shall find them to be, in

each, totally different; the effect which is

caused by the pressure of fluids upon solids,

and of solids and fluids upon each other, however

small that pressure may be, is invariably

attended with mechanical destruction, and loss

of substance.* In the one, the degree of mechanical

destruction altogether depends on the

quantity of pressure applied, and of motion pro-

* In the living system, instead of a waste being produced,

an increase of substance generally ensues.

WITH RELATION TO VITALITY. 2S

duced ; in the other, the natural actions of the

living system contribute to the acquisition of

strength. Great and striking as appear to me

the marks of difference by which systems, common

and living, are characterised, all comparison

is lost, when we reflect on the imbecility

and passivity of the one ; on the irritability and

mobility, (both voluntary, involuntary, and

mixed of the other,) with the power of abstraction,

and of ratiocination of some ; of reproduction

and restoration of all. If the food be

examined which subserves to supply the wants,

and to restore the wastes which every living

system undergoes, it will be found in its attributes

to be totally different from what it

was before. The commutation which the

food has undergone, after the process of digestion

has been accomplished, is total and

complete. Gases are bereaved of their expansibility,

adds of their acidity, alkalies of their

acrimony ; all of the order of their affinities,

and rendered bland and mild : by them, solids

are liquified, liquids gelatinised and made solid;

things simple become compounded; such as are

inanimate are animated ; animated things are

killed and revivified ; the most sapid bodies are

rendered insipid; the most putrid matter is deprived

of its putridity, and made antiseptic and

fresh; the most fresh and antiseptic is rendered

susceptible of undergoing the processes of pu3$

PROPERTIES OP MATTERT

trefaction and fermentation- Language itself

is insufficient to describe the difference which

exists between the laws, by which, animated

beings are governed, and those, to which matter,

either dead or common, is amenable.

While the phenomena which common matter

displays are regular and definite, and uniformly

and invariably the same ; we behold, on the

contrary, the same kind of matter applied to

different living systems, as well as to the same

Systems at different times, changed into a nature

totally different : we behold, in the same

field, and in the same soil, a multitude of different

vegetables fed and nourished by water

and by air, in quality precisely the same, and

yet assuming an organisation and form totally

different,

It is well observed by Mr. MASON GOOD,

(whose learning and research I am happy to

acknowledge,) that the most burning sands of

hot climates, even the karo fields of the Cape

of Good Hope, (so sere and adust that no water

can be extracted from them,) are the media

in which the most succulent vegetables of

Which we have any knowledge flourish and

evolve ; so deleterious, indeed, is a wet season

to their growth, that they are destroyed by it.

There are also various tribes of vegetables that

are destitute of radicles, and which can only

be supported and nourished by the air, and by

WITH RELATION TO VITALITY, 31

ihe moisture which the atmosphere contains ;

a large portion of tire class of fuci has no root

whatever. It is also stated that the aerial

epidendron, the epidendron flos aeris, (denominated

aerial from its’ extraordinary properties,)

a native of Java in the East Indies, on account

of the elegance of its leaves, the beauty of its

flower, and the exquisite odor which it diffuses,

is plucked up by the inhabitants, and

suspended by a silken cord from the ceiling

of their apartments, from whence it continues

from year to year, to put forth new leaves,

to display new blossoms, and exhale new

fragrance,-^-although fed out of the simple

bodies I have before stated.*

This assimilating and convertible power over

different kinds of food in the digestive organs,

is equally proved by animals, whether herbivorous,

carnivorous, or omnivorous. Meat cut

out of the same joint, bread from the same loaf,

water drawn from the same fountain, and portions

of air separated from the same volume,

given to a man or a monkey, to a dog or a cat,

will lose every vestige of its former qualities,

and be converted to the particular nature of the

system- to which it had been applied.

* See Mr. GOOD’S Oration before the London Physical

Society.

32 PROPERTIES OF MATTER

This power of decomposing the most minute

particles of matter, which the assimilating organs

possess, and of converting it to the nature

of the system to which it has been applied ;

although obvious to the most simple observation

of the most common observer, has been

further ascertained by experiments. Mr. ABERNETHY

procured a rabbit, six weeks old, and

fed him with’a quantity of young cabbage and

lettuce which had grown on flannel, sprinkled

with distilled water; the animal, it was found,

preserved his health, as perfectly, as if he had

been placed in a warren.

Dr. FORDYCE enclosed in glasses, filled with

common water, several gold and silver fish ; at

first, he changed the water every twenty-four

hours, and afterwards, every three days; on

this food alone, the fish continued to live and

to grow for fifteen months. As Dr. FORDYCE

suspected that it was possible, animalcules

might have previously existed in this water, he

exchanged the well for distilled water : after

adding air to it, to prevent the possibility of

insects getting access within the vessel, he carefully

closed it up : the fish, however, grew and

performed all their natural functions as perfectly,

as if they had been swimming in a reservoir.

The fact is equally proved by those animals

who live principally upon carrion, upon rotten

cheese, and the exuviae both of animals, and

RELATION TO VITALITY. 33

Of vegetables ; although corruption is not the

cause ofanimation, animation often flourishes,

with the greatest vigor, on the materials which

corruption has produced.

We should find it generally the case, were

we to take a cursory review of the different

kinds of food, which, different classes of men

take for their nourishment ; however different

the materials may be on which they feed, the

blood and the flesh ofwhich they are composed,

possess the same properties, and yield, by

chemical analysis, the same product ; whether

of a Bramin who lives on vegetables alone, or

of a Tartar who is carnivorous. I would appeal

to the testimony of any determined venisoneater,

whether he has not frequently enjoyed

the green fat of a stinking haunch, without retaining,

in his own person, any of its offensive

flavor. This converting power of the assimilating

organ on putrid matter, was proved by

Mr. HUNTER, and SPALLANZANI. They thrust

pieces of the most putrid flesh, tied by a string,

into the stomach of different dogs, and after

leaving it for some time, by means of the string,

they withdrew the meat from the stomach ;

and, ‘on examining it, they found, that instead

of being putrid and offensive, as at first, that it

had become fresh and sweet.

That all the effects which I have above enumerated,

are accomplished by the activity and

P

34 PROPERTIES OF MATTER

power of the gastric juice, which is secreted

from the surface of the stomach, is admitted by

physiologists in general ; a great diversity of

opinion, however, exists in respect to the mode

of its operation; by a few, very few indeed, it

is concluded, that it is performed by a living

power, resident in this fluid ; by the generality

of others, that it is the consequence of a che-i

mical, not a living, power. If it be by a chemical

power, we ought, by analogy, to expect

that its chemical properties, by analysis, would

be detected ; that it ought to possess some

sensible properties ; that it is either acid, or

alkalescent ; so far, however, from possessing

sensible, or chemical, properties adequate to

account for the extraordinary power which it

possesses, –it appears, upon a close examination,

to be a mere mucous fluid, inodorous and

insipid, neither acid nor alkalescent, neither

turning vegetable blues to a green, or to a

red color: and, by chemical analysis, it

yields neither saline, nor mineral substances.

It is, therefore, I contend, impossible to refer

the action of the gastric juice to any chemical

power which it is pretended to possess ; but,

that it is far more reasonable to conclude that its

activity is, altogether, derived from the energy

of the living power which is supfradded to it,

whose edge is sharper than that of the keenest

knife, whose solvent property is more active

RELATION TO VITALITY. 35

than that of the most eroding caustic. Such,

indeed, is the activity of this living juice, that,

although it remains, during life, in harmony

with the organ by which it has been produced,

its own power, notwithstanding, extends and

continues after the death of the organ itself has

taken place; hence it is, that the stomach has

then been found corroded and destroyed, more

especially in its pyloric extremity, and after

making its way on surrounding parts, these

have been found torn asunder and finally dissolved.

This solvent power was abundantly proved

by REAUMUR, by Dr. STEVENS, and others;

they introduced different kinds of food in balls,

some of which were perforated, and others

which were impervious : the food placed in the

former, to which the gastric juice could have

access, was very easily digested, while the food

contained in the latter remained unaltered.

When we contrast the uniformity of effect

which ensues from chemical combination, with

the variety which results from the assimilating

power of the digestive organs ; we must,

necessarily, be led to conclude, that the effect

produced does not proceed from a chemical

cause. If it arose from a chemical cause, the

change which the food sustained, by the mutual

action between its parts, -would be regular and

uniform ; and the result, instead of being always

D 2

36 PROPERTIES OF MATTER

alike would be generally different. It would

constantly vary, in its properties, according to

the specific nature of the substances, out of

which it was made. The change itself would

be constant and definite, and not liable to the

remission and variation which we witness during

the process of digestion. It is, therefore,

legitimate to conclude, that the process of digestion,

by means of which different kinds of

food are assimilated to one and the same species,

is not a chemical, but a living, act ; and

that the efficient cause of this commutation

does not arise from any active or chemical property,

which in the food inheres, but, that it

proceeds from the power of the organ alone, in

which it is received, and by whose energy, the

, new arrangements of the parts are formed.

It is this unifying power, which the assimilating

organs possess over materials discordant

and heterogeneous ; by which the act of digestion

especially differs from aggregation simply,

or the more complicated phenomena arising

from chemical union and combination. This

assimilating power pervades throughout the

whole range of animated existence. It is, in

essence, the same in animals, *as it is in vegetables

; however diversified the construction of

the organs may be, by which the effect is produced.

In all these, the organs are designed

to reduce different substances to one kind, that

WITH RELATION TO VITALITY. 37

this one substance may be in harmony with the

system at large, and fitted to be acted upon by

the particular power of the different organs,

into various forms. When the assimilating organs,

therefore, perform their functions with

force and with efficacy, they possess the power

of changing and of destroying the sensible and

chemical qualities of the substance they receive;

they not only possess the power to act, but to

resist action ; to change things external to

themselves, without being changed by external

things ; to cotivert them, instead of being converted

by them.

The matter, therefore, which every living

system receives for its nourishment and support,

can only arise out of its aptitude, and its

aptitude proceed from its imbecility and weakness

; from its state of disorganisation and

deprivation, total and complete. It is while it

subsists in this weak and destitute condition,

with relation to the power of a living system,

that, I say, matter is a mere tabula rasa, in all

its parts a chaos of power and of intelligencies

altogether void ; as imbecil and inert, as the

shoe without the foot, or, as the musical instrument

without the art or power of the musician.

It bears the same relation of weakness to the

power of the organ, as the uncolored paper on

which I write, does to the letter I am now

writing ; or, as the block does to the statue.

38 PROPRTI$S OF MATTER

If the block were already chiselled into a statue,

the prior existence of that statue would render

the marble, while in that figured condition, unfit

for the art of the statuary ; tut, being a

plane surface alone, it becomes a fit recipient

for the figures, which the artist intends to engrave.

That this is the relation which actually

subsists, of power and of weakness, between

the receiver and the thing received between

the organs and the food is proved by examining

the converse of the proposition. If the

food, which every living system receives for its

nourishment and support, acted by virtue of its

chemical, or its sensible qualities ; whether of

aggregation or configuration whether of color

or of flavor ; these qualities would constantly

resist the power of the organs, a.nd would

oppose the change, which the matter, by them,

was designed to undergo. Instead of vegetable

and animal matter being converted into chyle,

fermentation and putrefaction would invariably

take place ; if solid substances had been taken

in, for food, those substances would obey the

order of their affinities in the system itself, as

they are prone to do, out of it; a chemica.1

union between the parts would take place and

compound salts be formed. Finally, if they

retained any active or corrosive power, they

would enter into a union with the organ itself,

a caustic eflfect would be produced, and a conWITH

RELATION TO VITALITY. 39

sequent decomposition of it would ensue ; or,

if the matter received, acted by virtue of its configuration,

it would irritate and destroy ; laesion

#nd destruction would be the consequence.*

* The mechanical action of foreign bodies, on the organs

of which the ystem is composed, was particularly manifested

in the man who had swallowed a number of knives. The

circumstances of his case are so singular and extraordinary,

that had I not myself seen the knives, and been perfectly

acquainted with all the circumstances of the case, from Dr.

BABINGTON and Dr. CURRY, two eminent physicians who

attended him while he was a patient in Guy’s Hospital, 1

should feel some difficulty in giving credit to it. The circumstances

were narrated in a manuscript, in the form of a small

book, which was found in the pocket of the man, after his

death j and, as the particulars stated in it, corresponded with

the symptoms of his disease, and especially with the appearances

on dissection, after death, there is every reason to suppose

that the whole is correct. He stated his name to be J.

CUMMINGS, aged 32 years, by occupation a sailor; that, being

at Havre de Grace, he went, accompanied by some of his

ship mates, to a fair held in the afternoon of a Sunday. At

this fair he saw a company of strolling players performing a

variety of tricks ; an account of which he detailed. On their

return, to the sailors on board, among the most remarkable

of the buffooneries which they had witnessed, (with the exception

of Cummings) none appeared so extraordinary, as that of

the man who apparently swallowed a number of knives. Cummings

offered to do the same thing. Being urged by his companions,

he not only actually swallowed his own knife, bat

four other knives, which belonged to the other men. The

knives were all clasp-knives with horn handles, such as are

commonly used by seamen. In the course of three days, he

40 PROPERTIES OF MATTER

If it possessed any permanent power of solidity

or of fluidity the one could not, by the orvoided

them all. Six years after, being at Boston in America,

his fame for swallowing knives having spread, he was induced

one night, to swallow six, and the next day, while in a state

of inebriation, to swallow eight more ; and after very violent

efforts in his stomach and bowels, the whole of them were

voided. Soon after he arrived in this country, and while at

Portsmouth, in December 1 805, he got drunk, and swallowed

Jive knives, and on the sixth, nine more. The persons present,

asserted that he had swallowed four others ; but of this

he was not conscious. It appears, therefore, that in the

whole, he had swallowed at different periods, THIRTY-SIX

knives. The disease which these extraneous bodies produced,

can be better conceived than described. Sufferings, the most

acute, ended in a death, the most wretched. On opening his

body, there were found in his stomach, a large coat button,

with an anchor engraven on it, two silver ornaments, the

back of a silver knife, supposed to have belonged to a lady’s

fruit-knife, and thirteen blades, belonging to some of the

larger knives which he had swallowed. They were tolerably

perfect, as to figure, although much corroded ; so much so,

that the blades were reduced to very thin plates ; beside

which, there were a great number of smaller pieces, which,

apparently, had been separated from the blades. A large

piece of the back-spring of a knife, about four inches in

length, and very sharp at one end, was found passing through

the coloa into the abdomen: five others, in different parts of

the larger intestines, the coats of which they had pierced and

lacerated, and remained suspended in them, in different directions.

As this unhappy man, at the time of his death, was

under the immediate care of Dr. CURRY, of GUY’S HOSPITAL,

it is to be hoped, that he will publish a detail of all the

particulars, more especially* as he is so eminently qualified to

do justice to the case.

WITH RELATION TO VITALITY. 41

gans, be rendered fluid, any more than the other

could be rendered gelatinous or solid and, in

neither case, could it ultimately be fashioned or

formed into the different and varied parts, for

which it was especially designed.

The same reasoning equally applies to its

attributes of color and of flavor. If any particular

color in the food, permanently inhered,

that color would be constantly retained ; by

being retained, it would be always imparted to

the blood, and the complexion, instead of being

different in the individual of every species,

would be invariably the same. This is proved

when substances are introduced for food, whose

sensible properties cannot be altogether obliterated.

Hence it is, that madder imparts a red,

turmeric, a yellow, color to the system at large.

No proof, indeed, is more strong, of the disorganisation

total and complete, which the most

minute particles of matter, in general, undergo

by the process of digestion, than the loss of

flavor and of color which they suffer; the

most odorous and sapid, are rendered inodorous

and tasteless, the most colored, (as far as

it is possible) colorless, retaining no quality

whatever, bulk alone excepted.

It is by the energy of this same living power,

resident in the seed of plants, and in the fecundated

ova of animals, that the acorn becomes

evolved into an oak, the infant foliage expand4?

PROPERTIES OF MATTER

ed into leaves, and the whole process of nutrition

and of growth earned on. It is this power

which constitutes the architect and the fabricator,

by which the whole machine is erected ;

it is the base on which the whole stands, it

forms the bond of its elementary parts, the

cement that unites them into one whole ; it is

the cause primary and efficient, whence the

individuality of every living system arises, in

which the form and the sex it assumes, essentially

reside ; by which, the human species

differs from the brute, the brute from the vegetable,

the vegetable itself from matter inanimate

and common ; this power it is, which I

call life. The matter, which this power has

assimilated and organised, it is, which I call

living matter. It is this principle, which has

been named by ARISTOTLE, sifa$, by HARRIS,

form by STAHL, vis medicatrix naturte by

HALLER, vis vitce by BLUMEN BACH, nisusformativus

by J. BROWN, excitability (if the term

has in it any meaning), and by HUNTER, principle

of life. This last term appears to me so

appropriate and distinct, that I shall consequently

retain it. The principle of life may be

defined to be” thatpower, by whose energy different

species of matter are assimilated to one kind,

a living system organised and formed ; and the

various parts ofivhichit is composed, are protected

and preserved from decomposition and decay”

WITH SELATIO^ TO VITALITY

various organised systems, therefore,

which we behold around us, are nothing more

than effects, produced from efficient and producing

causes ; they constitute the obvious

.and manifest images, of which these primary

principles and causes are the prototypes. It is

very true, th$l these prototypes, or principles,

can only be known through the medium of their

effects ; that through the phenomena of life, we

can know any thing of vitality ; through sensation

of sensibility; through consciousness

of intellect ; through the works of creation,

that we can conceive a knowledge of the Creator

; or, as St. PAXIL eloquently describes it,

by which the invisible things of God from the

creation of the world are clearly seen, being

understood by the things that are wade ; even his

eternal power and Godhead.”

The relation of power which those principles,

or causes, bear to the subject, or matter, on

which they operate, is illustrated by every

phenomenon produced by animated beings in

general. It is, for example, by the power of

the artist, over the subject of his art, that he is

enabled to convert and to model it according

to his will ; that the statuary has the power to

chisel the marble into a statue ; the painter to

draw figures upon the canvas ; the carpenter

to cut the timber and shape it,|in the form of a

table, &c. &c.

44 PROPERTIES OF MATTER

It is the DEITY OMNIPOTENT, by whose

infinite power, the universe, in general, is governed

and directed ; who is the first cause, and

the first mover ; so it is the power of life

which constitutes the first cause, and the first

mover of every living system, in particular,

by which it is modelled and formed. Although

this living power is hidden from the

sight of the eye, we may, perhaps, gain a

glimpse of its nature by abstraction, or by the

analogy which subsists between its fabricating

power, and the operation of the mind, when it

employs the organs of the body as its instruments.

When an architect contemplates the

model of a palace, which he intends to erect,

and puts the design on paper, the form of

that palace had a prior existence in his mind ;

and the design on the paper, is nothing else

than the image, or the conception, which previously

existed in the mind of the artist ; the

one is prior, the other posterior, the former is

cause, the other, effect.

In like manner, when a man commits his

thoughts to writing, the letters described on

the paper, are nothing more than the pictures,

or representations of those which previously

existed in the mind; but, as every cause is

better than its effects, mental conceptions must,

necessarily, transcend corporeal operations. In

like manner, life itself, the cause of organisaWITH

RELATION TO VITALITY. 45

tion, must, in its essence, be as superior to the

organisation, as the hand of the artist is more

excellent than the pencil he employs. Organisation

is destined to display the phenomena of

life, as the powers of life unfold and impart

those of organisation ; it is, therefore, legitimate

to conclude, that life is not only a principle,

and a power, higher and prior to the organisation

itself, and a fortiori to the phenomena

that flow from it ; that the corporeal

parts of vegetables, and of animals, in common

with those of men, are nothing more than

instruments, subordinate and subservient to

this principle, by the energy of whose formative

power, one whole system is constituted and

formed ; instead of being formed by the same

means, as machines inanimate and common,

the whole formed and perfected by the addition

of various parts, by a power from without ;

we behold, in every living system, the various,

parts formed by a power from within, from

one united and indivisible whole. It is owing

to the unity and totality of this principle, or

power, that the various parts of the same system

are connected together, by one and the

same bond, why one part of the same system is

not separated, or distinct, from the other, but

that it is all in all, one whole.

It is the specific and individual nature of this

living* principle, or formative power, which

46 PROPERTIES OF MATTS&

stamps the character, and the features ofever?

living system. In its essence, it must be definite,

because the body which it has formed,

dnd in which it is contained, is limited in the

extent of its growth, and is prevented frohi acquiring

indefinite magnitude; although the

causes for its perpetual increase continue to

be applied. It must possess &jortnative power,

because every living system we behold, from

the most gigantic and complicated, to the most

insignificant and simple, is marked by a peculiarity

in the order and arrangement of its

parts.

In its energy, it must be active, not only because

it imparts activity and form to the passivity

and imbecility of matter, but becomes the

primary cause of the various operations which

this living matter performs. In that energy, it

must be temporal, because every living system

is transient and perishable, and in a constant

and unceasing state of progression, perfection,

and decay.

Admitting these undeniable truths, the conclusion

presses itself upon the mind with force

irresistible, that these attributes must, of necessity,

belong to a principle immaterial, and incorporeal,

by whose activity, matter formless

becomes organised ; by whose vivacity it becomes

endowed with the power of action, and

of motion; exerting the same influence, and

WITH RELATION TO VITALITY. 47

governing by the same laws, every particle of

this matter which it has assimilated ; and constituting

the power whence the organisation

originates the fountain, whence health and

disease are made to flow.*

* May we not be permitted to suppose, that the whole

visible world exhibits nothing more than so many passing

pictures, of which these principles are the prototypes, or exemplars;

and, that it is through the participation of them

which matter has acquired, that it may be said to have obtained

a semblance of immortality. May we not be allowed

to credit those speculative men, who, in times of old, have

told us, that it is in these comprehensive and permanent

principles, (or forms, as they have been called,) that the

Deity views at once, without looking abroad, all possible

productions, both present, past, and future ; that this great

and stupendous view is but a view of himself, where all

things lie enveloped in their principles, or exemplars, as being

essential to the fulness of his universal intellection. If

such be the case, the axiom so applicable to the materialist,

Nil est in intellects, quod nonpriusfuit in sensu, that there

subsists nothing in intellect which did not before subsist in

sense, must be reversed, and we ought rather to say, Nil

est in sensu, quod non prius fuit in intellectu, that nothing

exists in sense, which did not pre-exist in intellect.

CHAPTER III

ON THE EVOLUTION OF LIFE, COMPREHENDING

THE END FOR WHICH ANIMATED BEINGS

WERE CREATED.

THE existence of vitality, without organic

action, is proved by the seeds of plants, by the

ova of animals, by the foetus in utero, as well

as by torpid animals in a torpid state : it is

proved by the multitude of cases which we

constantly behold, in the foetal state, in which

many of the organs which are absolutely necessary

to carry on the functions of the adult system,

are altogether wanting. I have seen a

foetus without a head, others with a head, but

without brain; some without lungs, others

without a heart or lungs : many have been

found destitute of abdominal viscera, and with

various other malconformations of the system.

Although these organs were either defective, or

wanting, the other parts of the system were

EVOLUTION- OF LIFE* 49

found perfectly developed, and to have attained

their symmetry and form.

The existence of vitality without organisation,

would more evidently appear, if we

were to examine the state of the living principle

in the seeds of plants and ova of animals.

There are not, in them, any traces whatever to

be found of the future animal, or vegetable ;

there is no foetus in miniature, either of the one

or of the other ; and in animals, (more especially

in those belonging to the higher classes,)

gestation has continued, for a considerable period,

before any bond of continuity between the

different parts can possibly be detected ; neither

is the evolution equal in its progress

throughout the whole ; there are many parts

whose evolution has scarcely commenced, while

the development of others has been completed.

If foetal evolution depended on organic action

in general, a necessity would exist for the presence

of the various substances on which the

different organs are destined to act ; the admission

of air would be necessary to call forth the

action of the lungs ; the introduction of food

into the mouth, would be necessary to call

forth the digestive powers of the stomach.

If the foetus were so situated, its subsistence

would in a great measure depend upon choice,

not necessity ; upon choice without the power

of choosing, upon organic action before organi50

EVOLUTION OF LIFE.

sation had existed ; its condition would be one

of indigency and want, while destitute of tire

means by which its necessities could be supplied

; and the foetal system would resemble the

adult, without the power of arriving at that

state. It is far otherwise ; it appears to me

that the foetal constitutes a medium condition,

forming, on the one hand, a connected part of

the maternal constitution; and, on the other,

separated from it by its own individual existence.

That there subsists an individual existence

in both, separate and distinct from each,

is evident from many facts which we see, in

which the life of the foetus terminates while

that of the mother continues ; and, on the contrary,

in which the foetus survives the death of

the mother. The true end which nature has

in view, during the foetal state, is evidently to

organise those parts which constitute the means

by which the animal is able to provide for its

necessary wants, when the adult state begins :

hence it is, that the organs designed to accomplish

these ends, are especially distinguished

in the foetal state, by the rapidity of their

growth, and the magnitude which they have

attained, when the adult state has begun. I

may enumerate, as thejirst in order, the head,

with the organs of sense, and the nerves which

are connected with them ; secondly, the mouth,

trachea, and lungs ; thirdly, the heart and arteEVOLUTION

OF LIFE. 51

rial system ; the oesophagus and stomach, with

its auxiliary organs; namely, the spleen, the

pancreatic, and hepatic systems; the omenturn,

the intestinal canal, and lacteal vessels,

&c. &c. Under the second head, might be

mentioned, the bones and many of the voluntary

muscles attached to them, the generating

organs, and the venous and lymphatic absorbent

systems, the teeth, the hair, the nails, &c.

During the foetal state, the brain is in a state of

growth without consciousness, and of sense

without sensation ; the muscles are without

voluntary motion ; the lungs without respiration

; the stomach without digestion ; the intestinal

canal without peristaltic motion ; and

the lacteal vessels without absorption.

Although these different organs are in a passive

state, no doubt can exist of their possessing

a power to act, and that they only require

proper objects adapted to the nature of each,

to excite and display that power in the production

of action. It is this power of acting,

of the eye to see, of the ear to hear, of the

tongue to taste, of the stomach to digest,

which I denominate predisposition.

Predisposition, therefore, appears to be a

state of dormant power, or a power in capacity ;

it resembles the elasticity of a spring, while it

is coiled up ; it is like the figures engraven on

a seal, before they are participated by the wax;

52 EVOLUTION OF LIFE.

it is like the gunpowder before it detonates

and explodes ; the gunpowder possesses the

capacity to explode, the seal to impress the

figure, and the spring to react. These attributes,

however, which these different bodies

severally possess, would never be displayed,

unless they were placed under circumstances

fitted for the nature of each ; an unresisting

medium for the spring, a soft body like wax

for the seal, and a particular state of the air

for the gunpowder. It is the same thing with

respect to the living principle, and the different

organs which it has produced ; it not only demands

a certain state and temperature of the

medium in which it is placed, but particular

kinds of food, as well as particular conditions

of it, before that dormant power can become

poiver active, and the phenomena be produced

of organic action. It is in the development of

this power from capacity to energy, from pre^

disposition to action, by which means are employed

with a view to ends, and the final cause

attained for which animated beings were intended.

In proportion as the state of predisposition

departs, the state of energy accedes ; the

difference which subsists between both consists

in this ; in the one case, the organs, have

the power to act without having proper sub*

stances on which to operate ; in the other, the

power which the organs possess, is iro*edi*

EVOLUTION OF LIFE. 53

ately called forth by the application of the particular

substances which they require, and on

which their powers can be properly exerted.

The power, therefore, is resident within ; the

means by which the power is called forth into

energy comesfrom without ; the result of which

is, the production of organic action; the action

produced, is not the cause of life, as has been

falsely and erroneously supposed, but merely

an effect of it. Life, as we have seen before,

may, and does actually subsist without organic

action, although organic action cannot subsist

without the existence Oi* life : life had a prior

subsistence to the organisation, and organisation

itself to the action produced : life is the

primary and efficient cause, of which organisation

is the secondary and instrumental cause,

and organic action itself is thefinal cause. Physical

causes, therefore, may be divided into

two kinds; first, into primary, or efficient

causes, as the great first cause, and the principles

of intellect and of life, which impresses

motion on matter, the passive recipient of a foreign

impulse.* Secondly, into instrumental,

* A final cause, on the contrary, consists in the moral motive

upon the mind, and which can have no influence, but on a

Being that proposes to itself an end, for the action it performs,

chuses means, and thus puts itself in action : although a mechanical

force, and a moral motive are both causes, they derive

iheir energy from most opposite principles.

O4 EVOLUTION OF LIFE.

or secondary causes, which consist in the various

organs of the body, as the instruments

which it employs, in order to assist ; as a telescope

to the eye, a hammer to the hand, &c.

It is with a view to make the end subservient

to the means, of adapting the medium to the

nature of the being which it is to contain, to

produce, in fact, harmony and adaptation be-J

tween both, that the providence of God has

destined particular soils, and particular climates,

for particular classes of beings in which

those ends may be attained. When we behold

the regularity with which the actions of vegetables

are performed, as well as the simplicity in

the construction of their frame,- we are naturally

led to conclude, that those actions, constant

and definite as they seem to be, must flow

from the operation of causes which exist uniformly

and invariably the same, without any

opposing or controling power ; residing within

the system itself, by the energy of which those

actions can either be suppressed, or prevented :

there is not only a progressive development of

particular organs, from the first period of germination,

to the perfection of fructification ;

but an appointed season for the evolution of the

living principle itself, which the seed contains

; the end, of which seems evidently to be

the, propagation of the species, as the means of

affording nourishment and support to beings of a

higher class.

EVOLUTION OF LIFE. 55

The means by which the end is obtained is

not confined to one, but often extends to several

modes, and the offspring produced is perfect

in all its parts ; whether it has been evolved

from a bulb, or from a bud ; from a single leaf,

or from the seed itself. It does not, however,

appear from any knowledge which we possess,

that vegetables have any organs, either of sense,

or of consciousness, with which animals, in

general, are endowed.

When we behold the blossom o”f the sunflower

following the beams of the sun, from

east to west; the dioncsa muscipula seizing flies

by the contraction of its leaves, and making

them prisoners ; the sensitive plant becoming

tremulous and irritable throughout the whole of

its frame, when impressions are made on any of

its parts ; when various other plants have

their corolla opened and expanded, contracted

and closed, at particular periods of the day and

night, as well as under particular states of temperature

in the atmosphere ; I may, perhaps,

be permitted to assert, that these effects are not

the offspring of the living principle alone, but,

on the contrary, that they must proceed from

some small degree of sensitive power which

they may possibly possess, (consequently residing

in a nerve, or something analogous to it,

as the organ alone which is appropriated to

fulfil that office,) resembling the faculty which

56 EVOLUTION OF LIFE.

we see in the oyster, of opening its shell at the

afflux of the tide. This nervous power, how*

ever, if it be one, does not extend throughout

the whole of the vegetable system ; it is principally

confined to the efflorescence, at the particular

time in which it becomes unfolded, and

when it is about to fulfil the final cause of

its existence, in the production of fructification.

Admitting the possibility that something like

a nervous arrangement may exist in a few

species of vegetables ; in those which approximate

the closest, to the first order of the animal

tribe; it does not, however, appear that the

anatomist has detected its existence, or the

physiologist explored its power, in that large

and intermediate class of beings, of fuci and

madrepores, which connect the higher orders of

vegetables, with the lowest of the animal kingdom.

The hydra, or semi-transparent polypus,

when examined in the best light, through the

strongest magnifying microscope, seems to be

nothing more than a granular substance, something

like boiled sago, connected together into

a distinct and organised form by the medium of

a gelatinous substance. In the zoophytes, and

the lowest order of vermes, the whole of their

fabric is nearly of the same simple construction ;

the power of digesting, or assimilating the

^natter of the medium in which they are placed,

EVOLUTION OF LIFE. 57

extends over the surface of their system, similar

to vegetables ; insomuch, that when the

whole is cut into parts, each portion possesses,

within itself, the power of generation and nutrition.

As we ascend in the scale of animals, we are

able to distinguish, between different classes of

each, a considerable degree of difference in the

organisation ofwhich they are composed. Their

digestive organs, instead of being dispersed

over the whole external surface of their frame,

have a particular organ to which this office is

especially allotted ; while vegetables, in general,

act upon the fluid matter by which they

are surrounded, and convert it into nourishment;

animals, in general, on the contrary,

select it by means of the organs of sense, with

which they are supplied. Such, indeed, is the

absolute magnitude of the organs of sense in

these beings, that they can be easily de*

tected : the caterpillar has six eyes on each

side, and in the snail five eyes are distinctly

visible at the extremity of each of its horns,

exclusive of which, a number of fibrils arise

from its mouth, without doubt, imparting to

the sense of taste, an exquisite degree of sensibility.

In the bee, the eyes are not only of a very

large size, but owing to- the peculiarity io their

construction, the area of their surface becomes

3 EVOLUTION OF LIFE.

wonderfully extended ; in shape, they are like

a diamond, having, at least, one hundred sur^

faces, by means of which, they are enabled to

take within their sphere of vision, a great number

of objects.

The optic nerves ofjish far surpass, in magnitude

and power, those of terrestrial animals ;

  1. MONRO, who has written professedly upon

the subject, says, that the weight of the eye of

a cod, and the depth of its axis, are equal to

those of an ox ; added to which, there is a substance

called tipitum, placed at the bottom of

the eye, which, it is supposed, acts like a mirror,

in reflecting the luminous rays, so as to

enable the other parts of the organ of the eye

to condense them into a focus : by these means,

the concentration of the light to one point, is

so great, that fish can see, and distinguish distinctly,

objects at night. They are destitute of

eyelids, in order that they may be constantly

on their guard, to avoid the attacks of other

predacious animals.

The optic power of serpents, and of birds, in

general, and more especially of the predacious

order, is so well known, as scarcely to require

any detail. The following fact, will, however,

afford some idea of this wonderful power. MR.

BARBER, in the year 1778, being in company

with several gentlemen in Bengal, while on a

shooting party, killed a wild hog, which they

EVOLUTION OF LIFE. 59

left close to their tent, on the surface of the

earth ; in less than one hour after it had been

killed, at the time that the sky was so serene,

that there was not a cloud observable, a small

dark spot, at an immense distance in the air,

attracted their notice ; this spot gradually increased

in size, and they soon found that it

was a vulture, which was flying in a direct line

towards the dead animal, on which it immediately

alighted for the purpose of devouring. In

less than an hour’s time seventy vultures came

from all directions, some horizontally, but the

major part descended from the upper regions,

in which, a few minutes before, no appearance

of them was discernible.

Such, indeed, is the exquisite sensibility of

the eye of birds, that they are provided with a

membrane, (the membrana nictitans,) which

they are enabled to spread over the external

surface of it, so as to protect the retina from

the injuries which it might sustain, on particular

occasions, from the irritation of the solar

rays ; and we all know, that the owl, and other

birds, are unable to bear the light of day, and

that they consequently venture abroad during

the night season only.

The extraordinary faculty which these organs

of sense possess, is manifested under a

multitude of circumstances, which almost challenge

our credibility. Carrier pigeons have

60 EVOLUTION OF LIFE.

been transported to different and remote partfc

of different countries, and, upon being released

from their confinement, have returned, with a

letter round their necks, to the very spot,

whence they had been transported. The olfactory

poivers of dogs of particular species, are

equally certain ; they are enabled to follow

with the greatest rapidity, the game which

they pursue, by the effluvia on the surface ;

and, however, extraordinary it may appear, I

have been assured, that a dog belonging to a

regiment, which it was accompanying, in its

march from Glocestev to Greenwich, and which

had been stolen in the Borough, after making

its escape, returned, two days afterwards, to

the head quarters at Glocester, where it was

received by an officer, who had been left behind.

It is unnecessary for me to go into a

more particular detail of the power which the

organs of sense, in animals, possess ; it would,

however, lead to this general conclusion, that

they are far more active and acute than they

are in the human species.

Without the intervention of these organs of

sese, it is impossible that animals could obtain

any knowledge of external objects ; without

the eye, that they could obtain any knowledge

of color ; without the ear, of sound ;

without the olfactory sense, of flavor ; without

the tongue, of sapid bodies ; and, without the

EVOLUTION OF LIFE. 61

sensitive nerves, of sensation. This sentient

power seems inherent in the nerves which the

organs of sense contain, and these nerves are

the seat in which the proximate cause of sensation

actually abides. The cause of sensation,

does not abide in the external substance,

but in the organ by which the impression is

received. It is owing to this sensitive power,

that we behold animals display fondness and

aversion, action and remission, appetite and

inanition; it is by the energy of these organs,

that animals are able to distinguish,

without experience, in an intuitive manner,

not only the fitness of the medium in which,

by nature, they are destined to reside, but the

substances also, which are best fitted for the

support and nourishment of their frame. It

is owing to this sensitive power, that the dnck

and the chick in ovo, after having pecked open

the shell in which they were enclosed, take different

directions ; the one waddles into the

water, the other hops into the barn ; that the

infant, as soon as it is born, expresses by the

motion of its tongue and lips, its wants and its

appetites, and selects milk, and rejects vinegar

; that we behold in the leech, its fondness

for blood, and aversion to salt.

It is owing to the perfection of this sensitive

power, which these organs of sense contain,

that their energy is strong, and that the gratiti62

EVOLUTION OF LIFE.

cation of the appetite is the object to which all

their actions tend, and the motive by which

they are impelled ; by sense without reason, by

blind impulse, by fatal necessity, by brutal

instinct ; the final cause of which seems to be,

the gratification of the appetite as the MEANS,

and tJie propagation of the species as the END.

With the human species, it is far otherwise.

The inferiority of the organs of sense, in man,

with relation to those belonging to animals, ingeneral,

and the lower order in particular ; as

well as the inferiorty of his faculties of strength

and of motion, of sensation, and of propagation,

evidently prove, that a mere animal existence

is not his true destination. If the end

ofhuman existence depended on the extent and

perfection of living power, man would, in that

case, not only be inferior to the brute, but

the brute itself would be inferior to the vegetable

species : if it depended on the extent

and perfection of the organs of sense, the

condition of the brute would be far superior

to the condition of man, since the organs

of sense in the one, are far more perfect

than they are found to exist in the other.

What man is there whose digestive organs are

equal, in power, to those of animals in general ?

I have seen the stomach of a cod contain a

large haddock, the haddock to .have within

its stomach a whiting, and the whiting a smelt.

EVOLUTION OF LIFE. 63

The shark has been known, at one morsel, to

devour a man, and the large boa snake has

swallowed, without any mastication, animals

of considerable magnitude, not only pigs and

deer, but even a buffalo !

Witk respect to the power in the organs of

sense, the superiority of brutes over the human

species is equally evident. What man is

there, whose eye is equal, in acuteness, to predacious

birds, or to the animals of the feline

race ? whose olfactory organs can bear any comparison

with those in many species of dogs ?

whose muscles are equally strong with those of

the lion or the elephant? An elephant by the

power of its proboscis, will raise, with the greatest

ease, a thirty-two pounder ; and a lion, by

a stroke of his paw, will break the back bone

of a horse, seize, and carry him off between

his jaws, and afterwards devour him for food.

What individual is there whose loco-motive

powers are equal to those of the most sluggish

greyhound ? While our best pedestrians believe

that they have performed feats the most astonishing,

by walking for four or five successive

days, forty or fifty miles, assisted by intervals

of sleep and generous diet different kinds of

fish will traverse, without resting or sleeping,

from one continent to another. It is a well

known fact, that the same shark has followed

the track of the same ship, from the Indian

64 EVOLUTION OF Lilt.

ocean to the English channel, in order to devour

the offal by which it was allured, and

which had been thrown overboard.

If the comparison between vegetables and

animals, and especially the human species, were

made, with respect to the means by which their

wants are supplied, we should be led to admit

the self sufficiency of the one, and the total indigency

of the other. While vegetables flourish

and evolve for months, years, and even centuries,

by means of fluids only, of the” simple

nourishment of water and of air, which they

principally receive through the medium of the

soil, animals require not fluids only, but solids

also. In the one, the conversion of the food

from a common to a living state, is accomplished

by the easiest possible means ; in the other,

the agency of different organs is necessary, before

the process of assimilation can be accomplished.

While theformer flourish and propagate

without the necessity of having organs of

apprehension ; such is the imperfect condition

of the latter in these respects, that without organs

of apprehension, they could riot possibly

obtain the means of support ; they

would perish for want, without fulfilling the

end of their existence.

If we were to descend to particulars, we

should be at once convinced of the indigency

of the higher order of animals, in the propagate

EVOLUTION OF LIFE. 65

ing power which they possess, with relation to

those of a lower class, and more especially to

vegetables in general. An elephant seldom

produces more than one young in the course of

two years ; while, on the contrary, rabbits propagate

every six weeks. This power increases,

in an infinite degree, as we descend in the

scale of animation. Hens frequently lay forty

or fifty eggs in one season, and when we reflect

that pigeons can hatch nine times in one year,

it appears that they can multiply their species,

in four years, near fourteen thousand times.

In the amphibia, this prolific power is equally

observable. There was a turtle killed in London

a few years since, out of which, two thousand

five hundred eggs were obtained : the

quantity of ova that fish evolve is so immense,

that they are often known to cover, for the space

of many leagues, the surface of the ocean. We

all see the multitude of maggots that are generated

in rotten cheese, and of different insects

that are produced in different substances which

are undergoing the process of putrefaction

and fermentation ; a single mite has been

known, in the course ofa few days, to re-produce

its species at least one thousand times.

If we cast our eyes to the surface of the

earth, we shall be convinced of the prolific

powers of vegetables, <and of the lower order of

animals, with relation to those of a higher class.

66 EVOLUTION OF LIFE.

One single plant of elecampane will frequently

produce, in one season, three thousand seeds ;

the poppy, three thousand four hundred ; the

sun-flower, four thousand ; the tobacco plant

has been known to bring to maturity forty

thousand three hundred and twenty seeds.

The astonishing power, with which God has

endued the vegetable creation, to multiply its

different species, is more particularly manifested

in the elm. It is observed by a learned

commentator and critic,* that the elm produces

upwards of one thousand five hundred millions

of seeds, each of these seeds having the power

of producing the same number. How astonishing

is this produce ! At first, one seed is deposited

in the earth ; from this one, a tree

springs, which, in the course of its vegetative

life, produces one thousand five hundred and

eighty-four millions of seeds, this is theirs*

generation. The second generation will amount

to two trillions, five hundred and ten thousand,

and fifty-six billions. The third generation

will amount to fourteen thousand six hundred

and fifty-eight quadrillions, seven hundred and

twenty-seven thousand, and forty trillions ! And

thefourth generation from these, would amount

to fifty-one sextillions, four hundred, and eightyty-

one thousand three hundred and eighty-one

* Dr. CLARKE’S Commentary on Gen. i. 12.

EVOLUTION OF LIFE* 67

quintillions, one hundred and twenty-three

thousand one hundred and thirty-six quadrillions

!

Whatever the imagination of poets may have

conceived of the loves of plants, or whatever

may have been asserted by LINN^.US of the

SEXUAL SYSTEM, the truth of this system continues

to be very questionable and uncertain.

The various modes, by which the species are

multiplied, and the destitute state of nervous

energy in the parts which are concerned in that

process, decidedly prove, that they are not only

insensible to any feeling, but altogether unconscious

of the actions which they perform. If

any nervous arrangement has an actual existence

in them, it does not extend throughout the

whole of the system, but is confined to the

efflorescence alone, at the particular times,

when the corolla is unfolded, and when the

system is about to fultil the end of its existence,

in the production of fructification. How

debile and limited must this nervous power be

conceived, when we reflect on the immoveable

spot to which vegetables are fixed, and the

short life which the efflorescence is suffered to

enjoy. It is no sooner arrived at adolescence,

than its acme of perfection is attained, and the

period of caducity immediately ensues. The

system proceeds from germination to fructification,

from fructification to death, in a regu-

F2

06 EVOLUTION OF LIFE.

lar and unbroken tenor, without possessing, so

far as we can detect, any opposing or controling

power, by whose energy the vital actions

can be arrested or suppressed.*

By the condition of animals, as well as of the

human species itself, during sleep, ‘and more

especially as they subsist in the foetal state,

some idea may be formed of the nature of

vegetable existence. The foetus extracts nourishment

from the maternal system, to which it

is attached, as a cherry does from the parent

stock. Although it possesses organs of sense,

it is destitute of feeling ; and with organs of

consciousness and of apprehension, it neither

reflects on the means of supporting itself, nor

is sensible of its own existence ; an animal, in

the foetal state, is situated in a manner exactly

similar to an adult in a profound sleep, and

both resemble vegetable life. During sleep, all

the organs which subserve to the growth and

nutrition of the system, perform their functions

more perfectly, than they are found to do, during

a state of watchfulness. Respiration and

digestion, absorption and circulation, secretion,

as well as excretion, go on without the

energy of the will ; the energy of the will has a

tendency to impede these different functions in

* Mr. A. KNIGHT has decidedly proved that vegetables

have no sensation.

EVOLUTION OF LIFE. (59

their course : it is not the existence of the organs

which subserve to these purposes, which

constitutes the distinguishing characteristic between

vegetables and animals, as Mr. HUNTER

imagined. However varied the organs may

be, which subserve to the growth and support

of the system in animals, from what they are in

vegetables, they all subserve to the same use,

and are regulated by the same laws : in all,

they are intended to build and to erect a system

in the best possible way, fitted and adapted to

perform certain determinate ends. It is because

the ends are different in each, that there

exists a diversity in the means. While the

existence of a sensitive principle, of which a

nervous system is the immediate recipient, appears

to form the distinction between animals

and vegetables, and not the existence of a

stomach, as Mr. HUNTER supposed, so the

magnitude of the brain with relation to the

organs of sense, forms the principal grounds of

difference between irrational and rational animals,

between brutes and the,human species.

The physiologists who first directed their

attention to this subject, proceeded on wrong

data ; instead of comparing the magnitude of

the brain, with relation to the size of the nerves

which proceed from it, they compared the

relation which it bore to the aggregate weight

of the body. It is not, therefore, surprising.

70 EVOLUTIONS OF LIFE.

that from these data, the most inconclusive

reasonings should have been made. To Professor

SOEMMERING considerable merit is due,

for having put the subject upon its true footing;

he it was, who first pointed out that the magnitude

of the brain, with relation to the nerves of

sense which proceeded from it, was the true

point whence the comparison was to be made ;

it was from this mode of investigation, that it

was found, that, although the most irrational

systems have the largest nerves of sense, they

have the smallest brain ; and, on the contrary,

that the highest orders of animals have the

largest brain with organs of sense comparatively

small,

BARON HALLER observes, that in a boy six

years old, whose body weighed fifty pounds,

the brain weighed two pounds, three ounces,

and a half; and that when it is fully developed,

it may be generally averaged, in each individual,

at the rate of four pounds.. BLUMENBACH asserts,

that the largest brain of a horse which he

ever saw, weighed only one pound four ounces.

REDI says, that the weight of the brain of an

ox to that of its body, is, as 1 to 1154; and a

shark that weighs 300lbs. it is said, has a brain

that does not weigh more than three ounces.

In the snail, the brain is composed of a congre^

gation of nervous fibrils, which terminate in a

gort of trunk, of a semicircular structure. In

EVOLUTION OF LIFE. 71

the larvae and zoophytes, and that large and

intermediate class of beings which connect the

animal, with the vegetable, kingdom, although

there is a structure, of a nervous appearance,

which is expanded over the whole surface of the

body, the existence of a brain, as a distinct organ,

is not discernible. As we descend from the higher

to the lower orders, we shall find that the magnitude

of the brain progressively decreases from

the white, to the black, of the human species,

from bipeds to quadrupeds, from quadrupeds

to birds, from birds to fish, from fish to

insects, where all traces of the existence of

brains and nerves, as organs, separate and distinct,

are altogether lost. The extensive power

in them, which the organs of- sense possess, is

more especially calculated to attain those ends

which, in the great scheme of providence, they

are destined to perform : the sense of want and

of appetite, which the organs suffer, constitutes

the impulse whence all their motives spring, and

to the relief and gratification of which, all their (

actions are especially directed. It is the power

whence the impulse arises which may be called

instinct. It constitutes the principle, by the ‘

energy of which,, certain organs are employed

to perform certain determinate actions, with a

view to certain ends or consequences ; they are ,

impelled by natural and blind impulse, which

72 EVOLUTION OF LIFE.

they know not, and cannot resist; by fatal necessity,

by brutal appetite.

Beings, such as these, cannot be considered

accountable for the actions that they perform,

any more than vegetables, which neither feel,

nor reflect. These actions are always limited

and directed to the narrow limits of their particular

instincts ; however varied, in their direction,

in different beings those instincts may be,

they are invariably the same throughout the

life of the same individual, as well as of all belonging

to the same class ; and, are at once perfect,

not by previous instruction, or even imitation,

but by a sort of intuitive power which is

possessed throughout the whole race of animated

beings. Every particular class, therefore,

performs the same actions in the same way, and

with the same degrees of perfection. The

works of animals are, indeed, like the works of

nature, so perfect in their kind, that they can

bear the most critical examination of the mechanic

and mathematician. No human art has

ever been able to imitate the wonderful machinery

constructed by the power of the bee, or

the web, by the tentacula! of the spider. It has

been well observed by Dr. RE^D, (wrhose

authority upon these subjects must carry with

it great weight) that every manufacturing art

among men, was invented by some man, improved

by others, and brought to perfection by

EVOLUTION <JF LIFE. 73

time and experience: the arts of man vary in

every age and in every nation, and are known

only to those men who have been taught; but

the manufactories of animals differ, in toto, from

those of man. No animal of the species can

claim the invention, and no one ever brought

any one improvement, or any variations from

the former practice ; every one of the species

has equal skill from the beginning, without

teaching, without experience, and without habits,

and every one has its art by a kind of

inspiration ; not inspired with the principles or

rules of art, but with the ability of working it

to perfection, without any previous knowledge

of its principles, rules, or ends.

The analogy, therefore, which exists between

the vital organs of animals, and the whole vegetable

kingdom, although it proves that the living

principle, by which the system of each was

formed, is of the same nature in all, is, nevertheless,

distinct from it, in being destitute of

organs of sensation or of consciousness. The

actual existence of organs, not only of sensation,

but of consciousness, in them, shows that

they both feel and think ; the merest worm that

crawls upon the surface of the earth, feels ‘ a

consciousness of pleasure and of pain, of appetite

and gratification, of security and of danger;

it not only seeks for the means of satisfying its

wants, but is conscious of the danger to which

74 EVOLUTION OF LIFE.

it is exposed from different animals, by whom

it is devoured or destroyed ; we, therefore, see

it get out of their reach. Mr. Locke observes,

” that animals seem to have perceptions of

particular truths, and within very narrow limits,

the faculty of reason ; but we have no reason,”

says he,

” for supposing that their natural operations

are performed with the view to consequences,

and therefore not the result of a train

of reasoning in the mind of the animal.” So

far, however, from this assertion being well

founded, all the voluntary motions, on the contrary,

which animals perform, to me appear the

result of a motive which exists in them, and

that the organs which they employ, have objects

for their end. The acquisition of food and of

intercourse, are the consequences of the natural

actions which every animal displays ; it is

the nature of this impulse or motive, through

the power of which those actions are produced,

that constitutes the distinction in the appetites

of different animated beings, to the gratification

of which all their pursuits are especially directed.

If I were to enter into a particular examination

of the corporeal means which are possess*

ed by the higher and lower order, I should be

led to acknowledge the total indigency of the

one, and the self-sufficiency of the other. While

vegetables shed their seed upon the soil, and

EVOLUTION OF LIFE. 75

fish deposit their spawn upon the waters, and

different birfls lay their eggs upon the sand,

such is the perfection of the living power which

they possess, that the aptitude in the medium

alone, in which they are placed, is, in general,

adequate to answer every purpose of their

evolution and growth. In the higher orders

of beings, the evolution of the offspring

during the whole period of gestation, is totally

indigent of parental aid. The difficulty

and concomitant danger of parturition, progressively

increases, from the most simple to the

most complicated system, from brutes to the

human species, and more especially from savage

to civil life. The labor and anguish of the mother,

until that awful and important process is

accomplished ; the lamentations and cries of

the infant when born ; the total incapacity to

assist itself, or to obtain its own necessary

wants, all prove the imperfection and indigency

of the human frame.

The sense of want which the organs feel, and

the impression from external objects, are nearly

alike in the infant state of savage, as of civil

life ; all seem to have the same desires and the

same pursuits, and at that early period, human

life is entirely of an animal nature. It is equally

the case with savage nations in general ;

among them, the rules of social order are entirely

inverted; the weak falls a prey to the strong;

76 EVOLUTION dT LIFE.

women, instead of being the companions, are

the slaves ofthe men ; rapine is no crime, where

honesty is no virtue; killing is no murder,

where personal revenge is allowed ; and neither

adultery nor fornication constitutes a crime,

where promiscuous and incestuous intercourse

is tolerated. Among them, intemperance is

preferred to sobriety,^-ignorance mistaken for

knowledge, the passions and appetites of

youth preferred to the wisdom and virtue of

age. This state of degeneracy and of corruption

may be considered the condition of man,

when he allows himself to follow the pursuits

alone, to which he is impelled by the force of

sensual inclination. ST. PAUL, in his letter to

the Romans, tells them, that it was by this

condition that they were degraded and debased;

that they were impelled to act by the force of

passion without reason ; ^that they had the

propensities, and followed the pursuits of the

brute, without his instinct ; that they led, in

fact, a life of sense without reason. The apostle:

also tells them, that there was a law in their

members, which warred against the law of

their minds ; that the good that they did, they

would not, but the evil which they would not,

that they did. A condition, such as this, is not

the condition for which man was designed ; it

proves what he may, not what he ought to become

;

it proves, that the more he indulges his

EVOLUTION OF LIFE. 77

senses, the power of his mind becomes progressively

weakened; that instead of attaining the

prerogative of being a free agent, he continues

in the condition of a child, or of a man who

lives like a brute, impelled and chained down

by that fatal necessity of sin which he cannot,

in that state, avoid.

Miserable, indeed, would be the condition

of man, if the fatal necessity to obey the force

of passion to which the sensualist and the depraved

are doomed, extended to the whole

race ; if he were destitute of the power of directing

and of regulating the ideas, which, in

consequence, arise ; or, ifnone subsist, but those

excited by objects of sense. It has been well

observed by Dr. GJREGORY, on the inconsistency

of thefatalists, that if this were the case,

there could be no variety, and scarcely any

change in the pursuits of men ; the thoughts

would fio\v from each other, in one uninterrupted

series, and man could not be an accountable,

and scarcely a rational, being. It is, however,

very plain that we have a power of interrupting

a train of thoughts, and of dwelling more intensely

upon particular ideas, and even of

occasionally directing our reflections and contemplations

into new channels ; and this power

alone, is sufficient to constitute mail, a free

agent.

Although there are many parts in Mr.

78 IVOLUTIOX OF LIFE.

LOCKE’S book, that have a tendency to favor the

doctrine,

” that human actions are the result

of a necessity, which the individual cannot prevent,”

it is not, however, always the case ; on

many occasions, he is either driven or led to

acknowledge the free agency of man :

” This

I think,” says Mr. LOCKE,

is at least evident,

that we find in ourselves a power to begin or

forbear, continue or end, several actions of our

minds, or motions of our bodies, barely by a

thought or preference of the mind, ordering, or,

as it were, commanding the doing, or not doing,

such or such a particular action. The power

which the mind has, thus to order the consideration

of any idea, or the forbearing to consider

it, or to prefer the motion of any part of the body

to its rest, and vice versa, in any particular instance,

is what we call the will.” It is the particular

nature of this intellectual power in man.

which constitutes the distinguishing characteristic

between excellence and mediocrity, that

ought to mark out the individual from the species,

the man from the brute, and form the

real source of distinction in the attributes by

which different men ought to be estimated. It is

to the motives which spring and originate from

the mind, more than from the effects which are

produced by the organs as the instruments, that

we ought to attach merit or disgrace to them for

the actions they perform. It is from principles

EVOLUTION OF LIFE. 7

such as these, that we ought to conclude that

the man of science is to be preferred to the

artist; the wisdom and temperance of age,

to the appetite and passion of youth ; and

civil life to either savage or brutal. Intellect

bears the same relation to intellectual

things, as sense does to those that are material ;

and, as intellect is better than sense, it must

evidently appear, that intellectual pursuits are

to be preferred to those which are sensible or

material ; and, finally, that the objects of intellect

cannot be derived from objects of sense ;

otherwise, they would be subordinate, and not

superior to sensible things.

It is by the proper exercise of these

powers of intellect, directed to those objects

which seem to be congenial to its nature,

that man feels conscious that he constitutes the

first of all generated beings ; that although excited

by appetite and sense, he is nevertheless

able to resist, to subdue, and even to act in

opposition to those wants ; often compelling the

body to fast, when it craves for food, to receive

medicines which convey impressions nauseous

and painful ; to expose itself to the inclemency

of the seasons, and to various dangers;

to labor and to fatigue ; and patiently to submit

to death itself :

Decus et decorum cst pro patria mori,

80 EVOLUTION OF LIFE.

It was this sentiment which prevailed in

Cato’s mind, that enabled him to despise the

danger and the disgrace to which he was exposed

by the tyranny of C^SAR ; he felt that

the soul, secure within itself, could smile at

the drawn dagger, and defy its point ; that it>

could flourish in immortal youth, unhurt amidst

the war of elements, and the crush of worlds.

Admitting the truth of these observations,

(which must, indeed, have been apparent to

every reflecting mind) the conclusion presses

itself irresistibly upon the understanding, that

the end for which man was created, is totally

different from that of any other being.

Instead of being confined, like vegetables,

to the production of the species ; or, as in

the brute, to the gratification of the senses;

these objects constitute, in man, the lowest of

the ends which he is designed to attain : those

which are most congenial to his nature, and

which form the true end of his existence, more

especially consist, in the perfection of his

MIND, in order that he may be qualified to,

adore the ALMIGHTY, and become acceptable

to him.

While the attributes of vegetables consist in

the living and vegetative principles alone;

those of brutes in the vegetative, the sensitive,

and the irrational ; man, in addition to

these, possesses the intellective also ; and may

EVOLUTION OP LIFE. 81

be defined,

” a rational soul, in an animal body,

which it employs as its instrument.”

Say, why was Man so eminently rais’d

Amid the vast creation ? why empower’d

Thro’ life and death to dart his watchful eye,

With thoughts beyond the limits of his frame ;

But that th’ Omnipotent might send him forth

In sight of Angels and immortal mind,

As on an ample theatre, to join

In conquest with his equals ; who shall b

The task achieve, the course of noble toi

By wisdom, or by mercy, pre-ordain’d.*

Might send him forth the sovereign good

To chase each meaner purpose from his b

And thro’ the mists of passion and of sense,

And thro’ the pelting storms of chance and pain.

To hold straight on, with constant heart and eye

Still fixt upon his everlasting palm,

The approving smile of heaven 1

Akenside’s Pleas, of Imag*

* No doctrine has ever, perhaps, been more completely

mistaken, than that of predestination. By many, it has been

thought, that some there were, who were elected and predestined

to enjoy every blessing in this life, and happiness in the

next, notwithstanding the wickedness of their conduct ;

others again, that were doomed to suffer every misfortune in

this state of existence, and to endure eternal damnation hereafter,

however meritorious their conduct might have been.

If this explanation were true, instead of the Almighty being

what he is, all-bounteous, wise, and just, and the source of

all goodness ; it might rather be supposed, that he is the very

devil himself, and the cause of all evil. Great, indeed, is

the error ot” those who judge in this way. It is very true

G

82 EVOLUTION OP LIFE.

Such, however, is the immeasurable distance

which exists between the universal Intellect of

Almighty God, and the mind of man, between

the Creator, and the creature, between

the infinite Being, and the being which is finite ;

that the most perfect intellection, which proceeds

from the energy of the purest Intellect, is

as the dust of the earth, when the one is compared

with the other ; his attributes can no more

be apprehended, by matter, in general, which

is destitute of life, than by vegetables, or by

brutes in particular ; by vegetables., which

possess vitality without sensibility ; or by

brutes, who have sensibility without intellect.

The brute himself, no more than man, who

leads the life of a brute, whose whole thoughts

and actions are directed to the gratification of

his senses, and whose senses are never gratified

until they are surfeited, can never, in that degraded

state, obtain any perception of spiritual

things, any more than those among us, who

believe that there subsists within them, no other

that, in the general scheme of Providence, predestination is

a’ doctrine especially foretold by revelation, that shall be the

lot of the elect ; but the elect grossly deceive themselves, if

any there be who suppose themselves pre-elected ; the only

way they can make their election sure> is by religion, and the

performance of the duties it enjoins. It is not, therefore,j?flrticular

men that are elected, but men ofa particular description*

which description the gospel has pointedly designated.

EVOLUTION OF LIFE. 83

power than what arises from the mere matter

of which they are composed ; the one can no

more have communion with spiritual things,

than the most ignorant and uneducated among

the sons of men, is able to understand the

highest branches of human knowledge ; to obtain,

for example, a perfect knowledge of geometry,

although totally ignorant of lines and

figures ; of all languages, without possessing

any apprehension of sound ; and of all sciences,

without any perception whatever of the truths,

or principles, on which they are founded.

Between the lowest degrees of instinct and

of sense, the offspring of animal existence and

the mind of man, there can be no understanding,

because there is no analogy between them ;

the most irrational animal is no more able to

apprehend the knowledge of the most rational

man, than the most rational man is able

to imitate the instinct of the most irrational

brute; the cause lays in the ignorance of the one,

and the wisdom of the other. No correspondence

whatever can subsist between beings

whose natures are separated by a chasm so

widely different. It is with a view of adapting

our meaning to the level of the understanding

of the brute, that we converse with them in

a silly unmeaning manner ; to them a wise and

intelligent conversation would be unintelligible

and foolish. Children, therefore, or men who

G 2

84 EVOLUTION OP LIFE.

act like children, have animals more immediately

under control, than the philosopher

who is replete with wisdom and knowledge.

If God, therefore, had not manifested some

portion of his attributes, by means which are

on a level with the capacity of the human race,

man must, for ever, have been ignorant of his

Maker. He, therefore,

” tvho at sundry times,

and in divers manners, hath spoken unto the fathers

by the prophets, hath, in these latter days,

spoken unto us by his Son/’ made of the same

materials as ourselves, born of a woman, obnoxious

to human wants, and liable to the same

dangers.

Although it is greatly to be deplored, that a

large proportion of the world continues deprived

of the benefit of the Christian dispensation,

there are few people congregated together

into one society, wlro are destitute of religion;

of a belief, that there exists some being superior

to themselves, and who, consequently, becomes

the object of their adoration and worship.

The very act of humiliation which they

offer constitutes them religious beings ; whether

the object of their adoration be symbolised by

the sun, or by the moon ; by a stock, or a

stone. It is by the particular doctrines which

particular religions enforce, that, men are directed

to particular modes of worship, and

EVOLUTION OP LIFE. 85

whence the moral conduct of the individual

takes its bend.

It is the especial object of the Christian dispensation

to teach man to have a knowledge of

himself, in order that he may know what he

really is : that, although he possesses within

himselfa soul, immortal and divine, this divine

nature is, nevertheless, full of corrupt affections,

from the depravity of the animal constitution,

by which it is defiled; that he is less

disposed to acquire the perfection of the one,

than to indulge the impulse of the other,

Christianity will teach man, that he is, by nature,

born in sin, and the child of wrath ; that, instead

of resisting the allurements of passion,

and of vice, he is prone to yield to their influence

; that instead of resisting, like the oak of

the forest, the hurricane force by which he is

assailed, he bends to temptation, like the willow

to the air ; and, that he is incapable of becoming

acceptable to the Almighty by his own

works.

Notwithstanding the fallen condition of man,

he is not left altogether destitute of attaining

the end for which he is designed. If he employs

the means, they are always within his

reach. In order, however, to obtain regeneration

from sin, it is absolutely necessary that he

should give up the ” old man,”

” be born again,”

>’ live in newness of life,” and in the simplicity

86 EVOLUTION OF LIFE.

of a child, follow the means of salvation which

are proclaimed in the gospel. By constant

watchfulness and humility, by abstraction from

passion and from sense, by self-examination

and repentance, by imploring, before the

throne of grace, aid of the Holy Spirit, man

attains that peace of mind which surpasseth all

understanding, that assimilation of soul to

the divine nature, which enables him to commune

with his God, and have his redemption

from sin secured, through the efficacy of his

Saviour’s atonement.

It is the efficacy of his faith in this atonement,

which enables him to triumph over indigence

and oppression, and rise in full vigor, when

appetite is no more ; to bear up against the toils

and turmoils of this life ; to smooth the brow of

care, and dispel the gloom of despondency ;

to sweeten the bitterness of grief, and lull agony

to rest. Religion ought, therefore, to consti.

tute the base of every national establishment;

and be the rock, which the whole nation, as

one man, ought to grasp. It ought to form the

main spring of man’s actions, the beginning, the

middle, and the end of his pursuits; and it is

humbly hoped, that, although the glad tidings

of salvation have been confined to particular

people, the efficiency of the atonement will

extend to all nations, kindreds, and languages,

/ C/

C IIAFTER V.

ON THE DOCTRINE OF MA

SECTION I.

The Materiality of Life examined arid refuted.

NOTWITHSTANDING the vague and indefinite

nature which I have proved, matter, in general,

bears, in its relation to the powers and attributes

of life ; notwithstanding the passive

condition to which it is doomed, the regular and

circumscribed motions which it is made to suffer,

or sustain ; it has not prevented a set of

men, who debase the very name of philosopher,

which they assume, by the appellation of Materialists,

from affirming and concluding, that

matter, in general, possesses the inherent power

of converting itself into organs ; in fabric, most

delicate ; in action, most extensive ; and in

form, most diversified : that by the congregation

of these organs, one whole system is constituted;

that the result of this organisation

forms life, and that out of this organised life,

88 DOCTRINE OF MATERIALISM.

action and motion are produced: so that

matter is the primary cause of which life is the

secondary effect.

As varieties of the same species, as chips cut

out of the same block, educated in the same

school, and instructed in the same principles,

are the oxygenous philosophers : physiologists

of a more modern date, and of feelings far

more refined. They have taken great offence

at the baser materialists, for supposing that

matter, in general, however gross, however

imbecile and inert it may actually be, could

possess any inherent power of kneading itself

into organs, endowed with animation and

spontaneous action. Although these philoso-^

phers virtually adopt the doctrine of the baser

Materialists, they vainly think they refine the

doctrine by limiting this important property to

oxygen in particular, instead of extending it to

matter in general.

It is, therefore, necessary to explore the

sources whence oxygen is produced, and the

manner in which it is obtained. Oxygen is

found in, and obtained from, the oxydes, or

calces of metals, and semi-metals ; especially

of red-lead, and the black calx of manganese:

it is more especially secreted by the last order

of animated beings by the vegetable kingdom

in general, as excrementitious and foreign. It

is this particular air this oxygenous matter

DOCTRINE OF MATERIALISM. 89

which vegetables, in the day time, are constantly

discharging from the whole external

surface of their foliage as urinous and feculent ;

and which the aberrations of these pure defecated

philosophers suppose, constitutes the

principle of life, in which all living power essentially

resides, the immediate and proximate

cause of irritability in man ! ! !

The rational mind turns away with nausea,

and with aversion, from the contemplation of

causes, that lead to such unseemly conclu^

sions ; it receives, with becoming indignation,

and is disposed to hold up to derision, and to

scorn, the folly of those pretenders to physiology,

who know not how lo separate the subject

matter of a body, from the power by

which it is governed, and to which it is wholly

subservient. The oxygen, before it is received

into the system, is as absolutely dead as any

particle of food which is introduced into the

stomach,

I flatter myself that these strictures will not

be considered too severe, when I proceed to

point out the intemperate and abominable system

which these visionary doctrines have produced.

I am naturally led, as an immediate

effect flowing from cause, to investigate the

Ttrunonian system a system which, I am

grieved to say, has generally prevailed at

home, as it does universally abroad ; not only

90 DOCTRINE OF MATERIALISM.

in theory, but in practice also. Instead of

grasping, and adopting the doctrine of the Materialists,

in its native dress, and ascribing to

the Almighty Power of matter, the essential

and original attributes of life ; it is to the residuary

and ultimate effects only, which matter

evolves, whence life originates, and to which it

is referred : instead of making life an origin,

and a principle, Dr. BROWN, supposed it to

consist in a forced state ; that it is an effect

only instead of a cause : he makes life to begin

at its end ; to consist in what he calls excitement

; and that this excitement, or life, is the

effect of which the exciting powers, acting on

the excitability, are the cause.

If this relationship actually subsisted, between

the exciting powers, and the excitability;

if the result of both, were the true cause

of life, life would then, indeed, be, what he

foolishly affirms it would be, a forced, not an

original state; an effect, not a cause ; an end,

not a beginning ; instead of animated beings,

being, by necessity, forced to die, they might,

by the power of excitation, be forced to live ;

so that, by the proper application of his stimuli,

he might perpetuate life for ever and ever.

Life might be changed and varied, exhausted,

augmented, and renewed to a high, or to a low

state, back again from a high to a low one, in

proportion as he chose to infuse into the system

DOCTRINE OF MATERIALISM. 91

his diffusible, or fusible stimuli, brandy or

water heat or cold oxygen or azote pleasure

or pain joy or grief.

Nothing, but a perverted way of thinking,

could have led philosophers, such as these, to

ascribe to matter, independently and abstractedly

from the energy and participation of life,

the power of organisation ; or, to have referred

to this organisation, the source of life, as its

cause. It is evident, indeed, that these gentlemen

move in an inverted order, and end where

they ought to begin ; they begin, by making

power to arise out of weakness ; symmetry

and order, from that which is naturally formless

and motionless ; and, finally, design and intelligence,

the attributes of things void of all consciousness,

and destitute of all sensation. Instead

of making organisation the effect of life,

they make life to be the effect of organisation ;

instead of making the phenomena of organisation

the end, they make it the primary and efficient

cause, in which life virtually originates

and abides, the source of life, indeed, at its

termination.

This silly hypothesis is at once refuted, by

the total impossibility which exists, of giving

a rational answer to this simple question ; to

the question which I have often had occasion

to put to many of our physiologists, who entertain

these opinions; What is the cause of

92 DOCTRINE OF MATERIALISM.

organisation ? What is the cause that the multitude

of seeds, and of eggs, which are deposited

in the same soil, and exposed to the same

air, are able to act upon the different substances

by which they are surrounded : to

convert them from a dead to a living state;

from a state of dispersion, to a state of combination

; from a tabula rasa to organisation and

form ; from chaos itself into symmetry and

order ; and from a multitude of separate parts,

into one whole system, total and complete?

Although I have frequently heard much ingenuity

displayed in reasoning upon this superstructure,

I have often witnessed much folly

and ignorance, in attempts to account for the

foundation of it. Instead of supposing that the

different organs, which different beings possess,

are the recipients only of these different powers,

and that the matter of which they are composed,

would, without them, be as imbecile and inert

as the shoe is without the foot, or as the musical

instrument is, without the art, or skill, of the

musician : it is to the matter alone that the

whole power is referred. An hypothesis, such

as this, is not more absurd than that which is

assumed, that the organs with which living beings

are endowed are the cause, primary and

efficient, of which vitality and intellect are the

effect. With as much reason might it be affirmed,

that the pen with which I write, moves

DOCTRINE OP MATERIALISM. 93

my hand, instead of my hand moving the pen ;

that the top moves the whip, instead of the

whip moving the top; that language is the

cause, of which rationality is the effect ; that

the nucleus of the earth, as well as the dirt and

mud upon its surface, are the causes of which

vitality is the effect; that the whole material

world is, in fact, the great first cause, of which

the Almighty is the secondary, or instrumental

cause; that is to say, that the second cause, is

the cause of the first, and that the effect produced

is the cause of the causes.

It evidently appears, that the materialists, instead

of attributing inertness to matter, make it

the first cause of motion ; they behold it destitute

of form, and of fabricating power, and yet

refer organisation to its imbecility ; they see it

matter impelled, and yet they make it impelling

matter. Instead of considering it the last and

lowest of things, they make it the first and the

best ; instead of separating the cause from the

effect, they constantly confound both together ;

they mistake the thing produced, for the power

producing ; the fact, (the thing done) for the

law. Instead of putting confusion into order,

they put order into confusion. The consequences

of this false philosophy are manifested

by the puerile knowledge which we possess,

being entirely circumscribed to effects only,

without any knowledge of cause;- to end*

04 DOCTHIKE OF MATERIALISM.

without means ; to history without definition;

to definition without axiom ; finally, to a nomenclature,

which never designates the nature of

the thing which it is designed to proclaim.

It is high time that absurdities, such as these,

should be banished from our schools of science,

and the rising generation rescued from the contamination

which they, in consequence, suffer.

So long, however, as the false hypothesis continues

to prevail, that matter is the cause of

which life and soul are the effects, no hopes

whatever can be entertained of any philosophical

reformation. I, nevertheless, will maintain,

that these opinions are not the offspring

of ignorance, simply ; but of two-fold ignorance,

of that state of ignorance, by which

men persevere in error, without being conscious

of it, and which sears the mind against conviction

and reproof.

SECTION II.

The Materiality of the Soul examined and

refuted.

THE erroneous opinion which the Materialists

entertain, respecting the nature of life, or

vitality, are even more striking, when they are

applied to the higher principle which man posDOCTRINE

OF MATERIALISM. 95

sesses of intellect, or soul. Instead of considering

the organs which the principle of life

has elaborated, as the mere recipient of its

power, as the secondary, or instrumental

cause, by the energy ofwhich, ratiocination, and

voluntary motion, are produced, it is to the

organisation alone subsisting as a cause, to

which the essence and power of soul are ascribed.

Nothing, however, can be more erroneous.

The error has been acknowledged by

the best, and by the wisest men, that have ever

flourished, in antient or in modern times : it

has appeared to them that the attributes of

mind, and of matter, are altogether different

and distinct from each other; and that no

modification of matter whatever, could account

for the formation of the soul. It must

be apparent, that if the soul is material, that

like the universal attribute which belongs to

matter, it must be composed of parts ; and,

that if it contains parts, that it necessarily

must be divisible ; that if it be divisible, it

must likewise be decomposable and resolvable ;

and if it be decomposable, it must be destructible

; and if it be destructible, it must be a composite

; and if it be a composite, it must have

triple dimensions of length, breadth, and thickness,

as the common attributes belonging to

matter, in general. If this were the case,

the accumulation of ideas, would pecessarily,

96 DOCT&INE OF MATERIALISM.

be followed by an increase in the bulk of

the organ, by which those ideas were received.

It is, however, very evident* that

so far from the attributes of the mind producing,

or increasing, the bulk in the body,^-the

body, by the exercise of the mind, is rendered

more active and energetic ; that, instead of manifesting

to the organs of sense, any sensible

qualities, the mind is altogether insensible to

them : and, instead of being nourished, like

the organs of nutrition, the food wkich is congenial

to its nature, is such alone as flows from

reason and understanding. It is, therefore,

legitimate to conclude, that the soul is not corporeal,

but immaterial ; that it is simple, and

without parts ; and, consequently, indestructible

and immortal: for dissolution can only

arise from the separation of one part of a

thing from another, but which can never take

place in a principle which is essentially simple.

If the attributes of mind depend on organisation,

how is it possible that any permanent idea

of things can take place? for ideas could never

survive the duration of the particles of matter

which subsist in the organ, by which those

ideas were received. Memory could form no

part of such a system.

Experiments, however, go to prove that the

most solid, in common with the softer and

more fluid parts of the body, are in a state of

DOCTRINE OF MATERIALISM. 97

constant flow and change ; and, that animals,

whose bones had been tinctured and colored

red, by the madder with which they had been

fed, had recovered their usual complexion in

the course of seven years, after the madder had

been discontinued. We may, from this infer,

that as the more tender parts of the system are

more rapidly carried away, that, consequently,

the recollection of past events could never extend

beyond that period. Cases have also occurred,

when patients, in consequence of disease,

have forgotten recent events, and, nevertheless,

possessed a perfect recollection of

those which had happened long before. A curious

instance of this kind happened to a man

brought to St. Thomas’s Hospital, with a concussion

of his brain, who, by proper treatment^

recovered. It was observed, during the progress

of his cure, that although he spoke to the

attendants, it was in a language which none of

them understood ; a Welsh milk-woman, who*

came into the ward, having heard him speak,,

entered into conversation with him ; it was then;

found that the man, by birth, was a Welshman,

that he had left his native land in his youth,

that he had forgotten his mother tongue, and

that, for the last thirty years, he had spoken the

English language alone. Since the accident

from which he had recovered, he only remembered

the events of his younger days, and

m

98 DOCTRINE^OF MATERIALISM,

had entirely forgotten the English language,

and the occurrences of the latter years of his

life.

The opinions which are entertained respecting

the materiality of the soul, have not even

the merit of novelty in them ; they had been

entertained by different men, at remote periods,

as well as in more modern days : by none, however,

have they been proved to be false and

absurd, (by arguments more legitimate,) than

by Dr. S. CLARKE, a century and a half ago,

in the controversy which he maintained with

Mr. DODWELL, the materialist. In the hope

that the force of his reasoning may produce the

same conviction to others that it has done to

me, I shall, for that purpose, select a passage

on the subject from his valuable work :

” That

the soul,” says he,

” cannot possibly be material,

is demonstrable from the single consideration

of bare sense or consciousness itself; for

matter being a divisible substance, consisting

always of separable, nay, of actually separate

and distinct parts, it is plain that unless it

were essentially conscious, (in which case every

particle of matter must consist of innumerable

separate and distinct consciousnesses,) no system

of it, in any possible composition or division,

can be one individual conscious being.

For supposing three or four hundred particles of

matter, at a mile or any given distance one

00CTRINE OF MATERIALISM. 9$

from another, is it possible that all these separate

parts should, in that state, be one indivi-*

dual conscious being? Suppose then all these

particles brought together into one system, so

as to touch one another, will they thereby, or

by any motion or composition whatever, become

one whit less truly distinct beings than

they were, when at the greatest distance ? How

then can their being disposed in, any possible

system make them one individual conscious

being ? If you would suppose God, by his

infinite power, superadding consciousness to

the united particles, yet still these particles, being

really and truly as distinct beings as ever,

cannot be themselves the subject in which that

individual consciousness inheres : but the con-*

sciousness can only be snperadded by the addition

of something, which, in all the particles,

must still itself be but one individual being.

The soul, therefore, whose power of thinking is

undeniably one individual consciousness, cannot

possibly be a material substance.” If, however,

it be supposed that the soul is a material

substance, and that the brain, or any other

part whatever is the organ where it resides, it

must evidently follow that the quality of this

organ must be made up of the individual qualities

of all its parts : for example, the bulk of

the body is made up of the sum of the magnitude

of all its parts ; its motion is nothing but

ttl

100 DOCTRINE OF MATERIALISM.

the sum of the motion of all its parts ; and if

thinking or consciousness can be supposed to

be a quality inherent in a system of matter, it

must be also the sum and result of the thinking

and cogitation of all its separate parts. We

should, therefore, have as many distinct consciousnesses

or minds, as there are particles of

matter of which the brain consists, an idea

fanciful and false ; for composition or division

of magnitude varied, in an infinite manner,

can produce nothing in the whole system

but magnitude ; composition, and variation

of motion, nothing but motion ; composition,

and variation of figure, nothing but figure ; and

so of every other quality whatever. If, however,

it be supposed that not the brain altogether,

but one particle of it alone, is the seat of

the soul, &c. that one particle being divisible

into two, there must, consequently, exist two

souls, not one soul, in the same system, and

that each must think apart, and not together.

ON SENSATION AND ITS OBJE

IF we proceed to examine the relation which

exists between the impressions made by external

objects on the organs of sense, with which

animated beings are endowed, and the sensations

which are, in consequence, excited ; we

shall find, that although it is very true, that in

order for sensations to be produced, the agency

of external means on the sentient principle is

absolutely necessary ; it is, nevertheless, most

certain, that the sensation itself does not abide

in the external substance by which the impression

is made, but in the living and animated

being alone.

That this is the fact, will appear, if the effects

are examined, which are produced by the

same impressions on beings of different classes,

as well as on the same individual at different

times. It is very probable, that impressions

102 SENSATION AND ITS OBJECTS.

of the same kind, and of the same strength, induced

on animals of the same class, and of the

same age, excite, in them, sensations of the same

kinds. It is, however, certain, that very different

sensations are excited by the same impressions

on animals of different species: that

impressions which excite the sensation of pleasure

in some, will be found to give pain to

others ; and the same objects are known continually

to vary in the sensations which they

produce : the hands and fingers of the same

individual, under different circumstances, if

plunged into water of the same temperature,

shall, at one time, excite the sensation of heat,

at another time, of cold; the undulation of

the air, which at one time will be scarcely audible

to the ear, will* at another, appear like the

voice of thunder, and give the sensation of pain,

(as in pJirenitis.) In a state of health, the same

degree of illumination which excites the sensation

of pleasure in the eye, in opthalmia,

will occasion a color resembling a flame of

fire.

A cup of cold water, which generally

quenches thirst, and gratifies the palate, in a

state of health, if merely presented to a miserable

being laboring under hydrophobia, will excite

the most dreadful convulsions that can be

conceived, as well as the most unutterable

thirst, with foaming at the mouth ; and will

SENSATION AND ITS OBJECTS. 103

accelerate death by the most agonising means.

If the sensations which beings possess, were

inherent in the external substances, instead of

those sensations being multiplied and continued

without end, they would be limited and confined

to the particular instant when the impression

was conveyed ; and unless it were continually

repeated, the sensation could never be recalled.

Facts, such as these which I have stated, and

of which there are no end, decidedly ppove that

sensation does not abide in the external substance,

but in the living and animated being

alone ; they prove that the sensation of sweetness

does not abide in sugar, flavor in a rose,

cold in snow, or heat in lire, any more than

pain in a whip, or in a sword. These different

bodies constitute the agents only, by which impressions

on the nerves of sense are made.

Although, in common conversation, we are’

in the habit of connecting impression and sensation

together, as if subsisting in one, and the

same subject, nothing can be more incorrect:

instead of confounding the impression with the

sensation, the one ought to be separated from

the other. The question to be determined, is

not, whether the sensations inhere in these bodies

; we might, with as much propriety, seek for

the living among the dead, and ascribe to death

the efficient cause of life ; to immobility the cause

of motion to ignorance, ofdesign to fatuity, of

104 SENSATION AND ITS OBJECTS.

thought ; to necessity, of free agency as affirm,

that these sensations do actually inhere in

them; that heat is in fire, cold in snow, whiteness

in silver, blackness in jet, &c.

The proposition to be solved, is this ;

what are the bodies which possess the power of

conveying impressions to the organs of sense in

general, by means of which sensation is produced?

What are the bodies, which impressed upon the

eye, shall cause the sensation of illumination in

general, and of color in particular; upon the

ear, the sensation of sound in general, and of

tone in particular ; upon the tongue, taste in

general, and flavor in particular ; upon the

skin, feeling in general, the feeling of pleasure

or pain, of heat or of cold, in particular?

A proposition, such as this, may be solved

with as much certainty by a child of five years

of age, as by a man who has lived to the years

of Methuselah : a child will, at once, affirm

that strokes or impressions made on him by a

rod, give him pain ; that a rose is fragrant ; that

gold is yellow ; silver, white ; jet, black ; sugar,

sweet; vinegar, sour; fire, hot; snow, cold.

Not that these sensations actually inhere in

these bodies, but that these bodies, impressed

u^on the different senses, produce or excite

upon them different sensations, to which different

and appropriate names have been given ; of

SENSATION AND ITS OBJECTS. 105

illumination and variegation, of flavor and of

odor, of hot and of cold. Mr. LOCKE,* therefore,

makes a very just distinction between the

properties which essentially belong to different

bodies, and between those which exist in our

own perceptions :

” while the bulk, number,

figure, and motion of the parts of fire or snow

are really in them, whether our own senses

perceive them or not, and, therefore, may be

called real qualities, because they really exist

in those bodies. But light, heat, whiteness, or

coldness, are no more really in them, than sickness

or pain is in manna. Take away the sensation

of them ; let not the eyes see light, or

color, nor the ears hear sounds ; let the palate

not taste, nor the nose smell; and all colors,

tastes, odors, and sounds, as they are particular

ideas, vanish and cease, and are reduced to

their causes, i, e. bulk, figure, and motion of

parts.”

While each individual organ can only obtain

a partial knowledge of any subject ; the eye, of

color, the touch of resistance, the nose of flavor,

and the tongue of taste; the mind on the contrary,

which subsists not like the organs in

parts, but as a whole total and universal, re-

* Locke’s Essay on the Human Understanding, ch.

  1. 100.

106 SENSATION AND ITS OBJECTS. .

ceives the impressions wholly and totally, and

contemplates altogether, and at once, the various

attributes of the body, a perception of which

the organs of sense had separately obtained.

While the organs of sense, therefore, distinguish

the particular attributes of a body, the mind, on

the contrary, receives and conceives these per*

ceptions, universally ; things partible it views

impartibly; things divisible, indivisibly; things

temporal, eternally.*

Although the organs of sense are the avenues

through which impressions from external objects

are first made, it is from the native vigor

and power of the mind, that ideas are made to

flow ; while the spark comes from without, the

flame resides within ; although it is set in motion

by external means, it is from the power of

mind alone, by which those ideas and motions

ought to be directed.

Hoping that I have succeeded in showing

that sensation does not abide in the external

substance, but in the sentient principle alone,

* While the different attributes which the organs of sens*

perceive, constitute the true sources, whence definition ought

to be derived ; nomenclature, on the contrary, is made from

the congregation into one point, of all the attributes together.

The definition of silver or of gold, is not confined to its color

only, hot to its color and density ; its diagnosis from other

bodies consists in its malleability and relative weight, &c.

SENSATION ANI> ITS OBJECTS.

it will be easy to understand, that what is void

of thought and of reason cannot be the cause

of thought and of reason ; that although sensation,

any more than ratiocination, cannot exist

without an instrument or organ; the organ is

not the cause either of sensation or ratiocination

; although right thinking and feeling may

not take place without a right disposition of

body, a right disposition of body is not as a

consequence, the efficient cause of right thinking.

The body, it has been well observed by a

celebrated divine, may hinder thought, but

cannot effect it ; the faculties of the soul like

the sun, may be obscured and eclipsed by an

interposing body, but as soon as the obstruction

is removed, the light will shine out again in

full lustre.

What are the individual properties of which

the different bodies are composed, whieh, impressed

upon the organs of sense, excite the

different sensations, is a physical not a physio*

logical question, and is more cognisable by

the natural philosopher, than by the physiologist.

It is the province of the chemist to analyse the

materials of which the different kinds of food

are composed ; to ascertain the parts which

constitute the difference, by which one species

of food is, in its nature, different from the rest;

108 SENSATION AND ITS OBJECTS.

beef from venison, madeira from claret; to

ascertain what are the constituent materials

which, flowing from different bodies, excite on

the olfactory sense, flavors so various and opposite;

to ascertain the quality of bodies

through which impulses are propagated, and

which excite on the auditory nerves the sensation

of sound, or why a bed of roses and a

bed of thorns, excite the sensations of pleasure

and of pain ; to ascertain the nature of the

atmosphere in general, as well as of the different

bodies which excite upon the nerves of

sense, the sensation of dryness and of moisture,

of heat and of cold ; to separate the matter

which excites the sensation of heat and of cold,

from such as excites the sensation of color ;

to prove what fire is, as well as ice. It is the

duty of the chemist to analyse the materials,

which, flowing from different bodies, excite

upon the eye the sensation of illumination in

general, and of color in particular ; not only to

segregate a beam of light into rays, but to analyse

each ray into its constituent parts; to separate

the matter of color from the matter of

light; and finally, to present the solar ray pure

and unmixed, as it subsists in its elementary

and uncombined state. Until ready and most

satisfactory answrers can be given to these points,

I shall consider chemistry most defective and

SENSATION AND ITS OBJECTS. 109

imperfect, undeserving the name of science, and

merely ranking on a level with other arts.*

The sensation on the surface of the body is

excited by the resistance which is opposed to

the nerves situated under the skin, the nature

and the design of which depend on the peculiarity

in the arrangement of the particles of

the external substances ; it is from that peculiarity

that we decide whether a body be solid

or fluid, whether it be rough or smooth, blunt

or sharp. In the organs of hearing, sound in

general is excited by impressions on the auditory

nerves, through the medium of the tympanum

; and it is owing to the various undulations

of the air, modified and altered by the organisation

of the external fabric of the ear, that

sound in general, is made sound particular;

sound particular manifested by the variety of

tones, so distinctly perceived by those who have

what is called a good ear. In the organ of

hearing, sound may be considered the genus,

tones, the species.

In the organ of smelling, the sensation of

odor is excited by the particles of bodies which

* I purposely omit to notice the analysis of any part of the

living system, whether of animals or vegetables; because

chemical analysis of any portion of it, can only be accomplished

after death ; and, consequently, during the life of the system,

the excretions alone are the parts, in examining which the

chemifct may amuse himself.

110 SENSATION AND ITS OBJECTS.

are applied to the olfactory nerves, through th<

medium of the scneiderian membrane: odor iu

general, is the genus, the quality of those odors

the species, whether aromatic or fetid. In the

organs of taste, the sensation of flavor is excited

by the different substances more especially received

for food, and which are applied to the

nerves of the tongue ; while flavor in general,

constitutes the genus, the variety of sensations

which different kinds of food produce, constitutes

the species. In the organ of vision, the

rays of color impressed on the retina of the eye,

excite the sensation of illumination in general,

(and like different articles of food which excite

different flavors,) different bodies conveyed to

the eye, produce different colors. Every substance,

therefore, in nature, which exists, of

which the eye has any cognisance whatever,

whether it is black or white, brown or yellow ;

or, in short, whatever color it may assume, so

long as it exists, the sensation of ill animation

piust be considered to be colored.

Had physiologists and chemists been properly

informed of the distinction which exists between

impression and sensation between the

thing received and the receiver between the

substance without and the sensitive principle

within we should have been spared the pain

of hearing opinions promulgated and taught by

those few, very few individuals, who lay down

law, and who have been deluding the world

SENSATION AND ITS OBJECTS. Ill

&r some centuries past, down to the present

moment; we should have been spared the

folly of being called upon to believe opinions*

that are not more revolting to the feelings, than

they are to the good, common, unsophisticated

sense and apprehension of mankind.

Instead of supposing, that the coloring quality

of matter abides in the body whence it

flows, like every other quality which causes

impressions upon the other organs of sense, it

is absolutely affirmed, and universally believed,

that the color of a body proceeds from what

the body does not possess ; instead of arising

from rays of color which issue out of it, exciting

upon the optic sense particular sensations,

to which the names of particular colors have

been given ; it is supposed, that the color of every

body proceeds from rays of color which were

never admitted within it

; but that are repelled

from it ; and that a white body is ivhite, because

it reflects all the rays, but absorbs none ; and

a black body, black, because it absorbs all

the rays and reflects none ; it is, therefore, concluded

that neither black nor white are colors.

I would, however, ask any of these persons,

whether the matter by which the sensation of

white or of black is excited, is not as actual

and potential, as that by which the sensation of

red or of green, &c. and whether snow and jet

have not an actual existence, as certainly as

gold and indigo.

112 SENSATION AND TTS OBJECTS,

Instead of supposing that the quality of matter

by which the sensation of cold is produced

is as absolute as the quality of matter by which,

the sensation of heat is excited, it is, on the contrary,

universally affirmed and believed, that

cold is a negative, not a positive property.

During the winter season, when we behold

fluids converted into a solid form ; water become

ice ; vegetation suspended ; animation often

rendered torpid and destroyed by mortification;

although these effects are produced

by that modification of matter called cold, it

may, perhaps, appear somewhat strange to men

ofcommon feelings, who possess common sense,

that the actual existence of the matter which excites

cold, instead of being admitted, should be

denied by all the most enlightened chemists and

experimental philosophers, as they call themselves,

of the present day; and that none but

ignorant fools, if any there are so foolish, dare

to think otherwise. It is also maintained, that

the effects which are produced in the polar regions,

as well as in other countries during the

winter, do not proceed from the matter of cold,

but that they arise from the privation of heat ;

as if snow or ice applied to bodies in whjch

those effects take place, have not an actual existence,

as much as a flame of fire by the impressions

from which the sensation of heat is

etxcited, and combustion produced.

CHAPTER V

ON fHE PHYSIOLOGY OF ORGANIC LIFE,

AFTER having detailed, what I conceive to be

the deplorable state of ignorance which generally

prevails respecting the nature and power

of the principle of life, arid of mind, as well as

the relation which matter bears to them ; I shall

proceed to show that the same ignorance exists

respecting the functions of the different organs

of which the animated system is composed,

through the energy of which the various ends are

obtained, for which animated beings areespecially

designed. That the nerves are the organs of

sense, as the muscles are of motion, comprehends

all we know of their nature ; but of the

manner how impressions received, are conveyed

to the brain, in which the impression

ends and consciousness begins ; and how volition

and motion are imparted to the different

muscles of voluntary motion ; whether these

i

114 PHYSIOLOGY OF ORGANIC LIFE.

effects are accomplished tli rough the medium

of a subtle fluid which the nerves contain, as

Sir ISAAC NEWTON and others with great probability

of truth have asserted, or according to

the opinion of some, by vibrations excited

through nerves of a solid fabric, like thrills on

a brass wire, is not only a matter of hypothesis,

but is as unknown to the best physiologist, as

it is to the rudest barbarian.* With respect tothe

cause of motion, although the subject has

occupied the attention of many ingenious

and inquiring men, at different times ; we possess

tfo other knowledge of it, than that the

muscles are the agents by which motion is

produced ; but of the cause why, we continue

in the most profc aid ignorance.

.The ignorance, at present existing, of thr

functions which I have mentioned, are especially

extended to those of consciousness. Although

the brain is the organ in which coiir

* The horrid cruelties which continue to be practised by

the Galvanic fire, and other means, on the gciatic nerves of

frogs, rather favor the former hypothesis; the experiment

once made, has ascertained all that ran be known from it, and

the fact might, therefore, be mentioned, but certainly ought

not to be repeated (as it is so often done) in order to produce

a Sort of stage effect, and to gratify ignorant curiosity. Little

did LORD BACON suppose, that the system ofinduction which

.he introduced, would have been converted into a system of

.torturf.

PHYSIOLOGY OF ORGANIC LIFE. 115

Iciousness resides, \ve are totally ignorant of

the manner by which its actions are displayed ;

how it is, that without being muscular in its

fabric, it is, nevertheless, the cause of muscular

motion ; how, though formed of parts which

were originally destitute of sense and of reason,

it, nevertheless, constitutes the instrument from

which the principles of sense and of reason

perpetually flow. Notwithstanding all analogy

justifies the opinion that the brain is an organ of

secretion, the fact has never been demonstrated,

and the most perfect ignorance exists, at this

time, how, this most important organ of the

whole system acts, and what is its nature.

This state of ignorance has been very candidly

confessed by Sir Busic HARWOOD, the present

learned and respectable professor of anatomy

at the university of Cambridge :

” When we

dissect the brain,” says he,

” and observe the

different substances of which it is composed,

and their different forms ; imagination, assuming

the office of reason, would willingly assign

a peculiar use to every part, and pronounce

one to be the residence, or rather the instrument

of memory; another of abstraction, a third of

volition, &c. When a sensation is excited by

the action of any substance upon the body, we

immediately perceive upon what part of the

body, the substance acts, where the impression

begins ; and as the impression is conveyed by

I 2

116 PHYSIOLOGY OF ORGANIC LIFE.

the nerves lo the brain, it is conceivable that

we might be so constituted as to perceive, with

the same facility, in what part of the brain the

impression ends. This, however, experience

convinces us, we are not able to determine.

The skill of the anatomist has demonstrated

every process, explored every cavity, and

would, if possible, have traced every filament

of this inexplicable mass, of that wonderful and

anomalous organ placed on the doubtful confines

of the material and spiritual worlds ! nor

have the physiologist or metaphysician been

less eager to discover or to assign to each part

its peculiar office ; whatever may be due to the

former for accuracy, and to the latter for ingenuity

and zeal, we must lament that little knowledge

has resulted from their labours. At this

advanced period of science, when almost every

subject has been illuminated by the experiments,

the deductions, and even by the conjectures

of the learned, we are not able to proceed

a single step beyond the fathers of medicine,

xvho, in the very infancy of our art, pronounced

this inscrutable mass of organised matter to be

the fountain and the reservoir, the beginning

and the end of the whole nervous system, where

every idea originates, and to which every sensation

is referred.”

Having investigated the subject of fecundation,

the result of which 1 have detailed at

PHYSIOLOGY OF ORGANIC LIFE. 117

large in my PHYSIOLOGY, as well as in two

papers published in the MEDICAL JOURNAL for

the year 1799, I shall merely observe in this

place, that the object which I had principally

in view, was to show, that the ideas entertained

on it by Dr. HAIGHTON, and which have been

published in the PHILOSOPHICAL TRANSACTIONS,

were altogether erroneous ; that he had

discarded and rejected all analogy whatever,

and the evidence which is furnished to ns by

vegetables, by fish, and by the amphibia, as

well as by other classes of animals. Instead of

taking the actual existence of a foetus, as constituting

the only infallible test of animal impregnation,

he assumed the formation of a corpus luteum

in the ovariurn for the evidence of it. I proved

that the very facts which he had advanced were

decisive in showing he had proceeded from

false assumptions ; that in all those cases in

which he divided the fallopian tube of one side,

and left the one on the opposite side, perfect

and undivided, although there were corpora

ititea in both ovaria, there were foetuses only in

the perfect, but no traces whatever of a foetus

in the mutilated side; that although oestrum

had produced an evolution of the ova in both

oraria, impregnation was apparent only in the

perfect one. Notwithstanding these facts which

he himself had obtained, he concluded that the

existence of corpora, In tea was the test of im118

PHYSIOLOGY OF ORGANIC LIFE,

pregnation; and from this false fact and false

assumption, he has proceeded to investigate the

subject, and to make from them the most erroneous

qonclusions. He might, with as much

propriety, have supposed that the ova of birds

which we see continually dropped from the

ovarium without impregnation, are actually impregnated,

or that the corpus luteum, which

is in consequence formed, is the test of it ; although

certain evidence existed that no union

between the pairs had taken place, and where

corpora lutea had been formed, but no impregnation

whatever.

So little is known, at this time, of the nature .

of Hood, that with few exceptions, the generality

of physiologists absolutely deny to it the

attribute of vitality. They deny the attribute

of vitality to that important matter, from which

every part of the living system is formed; which

supplies the wants, and which restores the

waste that different parts suffer. Mr. J. BELL,

who must be considered as high authority in

this matter, calls the vitality of the blood ” the

most monstrous of all absurdities.” The vita*

lity of the blood is an opinion almost as antient

as the Mosaic account of the creation. The

sacred writings tell us, that ” the life is in the

blood,” that is to say, that the life of the animal

or of the vegetable is in the blood, in common

with the other parts of the body ; not separate

PHYSIOLOGY OF ORGANIC LIVE. 119

distinct from it, but co-existing and connate

with it. That the blood is alive, was considered

by SERVETUS, two hundred and fifty years ago,

(it made one of the charges preferred against

him before he was brought to the stake), a

well as by onr illustrious countrymen HERVEY.

and HUNTER. It is greatly to be deplored, for

the cause of science, that Mr. Hunter’s active

and comprehensive mind should have been

destitute of those collateral branches of knowledge

which are intimately connected with the

science of physiology : he saw truth, but he

saw it at an unapproachable distance, he saw

it in a fog, he saw7 it through a glass darkly.

Although Mr. Hunter revived the exploded

doctrine of the vitality of the blood, he nevertheless

supposed that this vitality was, as it

were, separated from the other parts of the system

; that the blood had a life, sui generis, or

as he termed it, that the blood was an animal

within an animal ; imperium in imperio ; that

it possessed a sort of animation or power of ac

tion within itself, similar to muscular contrac

tion ; that it was by virtue of this power, that

bones were formed and renewed, and the various

processes of secretion and of growth

carried on ; that, in fact, all the phenomena

which are produced by it proceeded from powers

inherent in it.

These false assumptions grubbed up the road

120 PHYSIOLOGY OF ORGANIC LIFE.

which he himself had paved, of discovering the

relation which the blood bears to the organs ;

and at once blasted the fair prospect which he

had opened to our view, of seeing the nature

and design of secretion ; instead of which the

process of secretion, so important and extensive

in the living system, is acknowledged by

all to be involved in utter darkness.

Our ignorance of secretion appears to me, in

a great measure, to arise from mistaking the

relation which the blood bears to the organs by

the energy of which it is acted upon and chang-r

ed ; instead of considering blood as the passive

recipient, as thesubject matter to be acted upon,

not only by the vessel in which it is contained,

but by the organ in which it is deposited ; it is to

the stimulus of the blood, more than to its aptitude

to be acted upon by the organs of secretion,

that the changes which it undergoes are referred.

The relation which subsists between the matter

from without, and the digestive organs

within, is precisely the same, in kind, as that

which subsists between the blood and the vari^

ous parts to which it is conveyed. While the

digestive organs unify and assimilate different

species of matter to one, and the same kind, and

which afterwards subsists in the form of blood ;

the different secretory organs, on the contrary,

have the power to convert this blood into fluids

and solids, in their nature totally different ; as

PHYSIOLOGY OF ORGANIC LIFE. 121

we behold in the various secreted fluids that are

produced from the blood of the same animal

and the medulla of the same plant. Blood

bears the same relation to the power which the

organs severally possess, as brick and mortar

do, to the architect or to the artist, by whom a

building is erected. It has no more the power

to convert itself into organisation or form, than

brick and mortar have, of themselves, the power

to erect a building. If it possessed any power

of action within itself, by virtue of the sen*

sible properties it contains, it would resist the

action of the organs to which it was applied,

it would act upon them, instead of being changed

and converted by them : if it had the power

of converting itself, by itself, either into different

organs or into different fluids, the previous

existence of those organs would be unnecessary,

since the process of conversion and of secretioji

would take place without their influence. We

might as well suppose, that a building can be

erected without hands, and designed without a

designer; an effect produced without a producing

cause; or, what is equally absurd and

false, that the effect and the cause are inherent

in one and the same subject.

By virtue of its passivity, the capacity of

blood arises not only of being moved, but of

being changed and organised ; it has the capacity

of being moved without having any power

122 PHYSIOLOGY OF ORGANIC: LIFE.

of moving itself; following, without resisting,

the impulse it receives from the vessels in which

it is contained. It has the capacity of being

changed by the power of the part in. which it is

deposited ; yielding without resisting, as the

softened and adapted wax to the force of the

impression engraven on a seal. It bears the

same relation to the secretory organs, as air

does to the organs of sound ; if the air expired

from the kings, inherently possessed any particular

sound, that particular sound would constantly

manifest itself; but air being destitute

of all sound, retains the capacity alone of being

expanded and compressed ; it thereby becomes

fitted to be acted upon by the organs of speech,

and through their power it is modulated and

harmonised, arid language ultimately produced.

It is with a view of preserving this aptitude

in the blood of animals, and of preventing the

sensible qualities which the coarser parts contain,

from being employed; or exerting any influence

upon the organs ; that we behold the

design and end for the exhalent termination of

arteries in capillary tubes ; by means of which

a mechanical cause exists to prevent a mechanical

and deleterious effect. If it were not for this

mode of construction ; if the terminated diameter

of the exhalent arteries w^ere large instead of

small, not only the more tenuous, but the more

globular parts of the blood wrould be permitted

PHYSIOLOGY OF ORGANIC LIFE. 123

to flow through ; those parts of the whole would

flow through, which possess quantity with

color and figure; quality without aptitude;

that would act upon the organs instead of retaining

the fitness alone to be acted upon by

them. To prevent this evil, a gradual diminution

in the size of the secretory vessels exists,

in order that the fluid which they exhale may

answer, in the best possible manner, the end for

which it is designed; this fluid is, therefore,

tasteless and inodorous, colorless and tenuous.

If blood possessed any power of action within

itself, it would resist the action of the organs

to which it was applied ; it would act upon

them, instead of being changed and converted

l)y them ; it is moved without the power of

moving itself; it is propelled without resisting,

and follows the impulse it receives, from the

power of the vessels in which it is contained ;

not according to the principles by which fluids

are moved in hydraulic machines, but by powers

altogether different from them. The relation

which exists between the blood and the vessel

in which it is contained, is precisely the same,

in kind, as subsists between the glands on which

it is deposited, and the blood : while the power

of the one is similar to the figures engraven

on a seal, the other resembles the softened

and adapted wax which is to receive the impression.

It is by the energy of the former, and

124 PHYSIOLOGY OF ORGANIC LIFE.

aptitude in the latter, that the various processes

of secretion and nutrition are carried on. Instead,

however, of supposing that the changes

which are produced on the blood, arise from

the agency of the glands, or of the part in which

it is deposited ; the change, for the most part, is

referred to the; power of the blood upon the

gland ; the act is stated to be a chemical, rather

than a living one ; and the aggregating principles

of physiology have been abandoned to the

decomposing powers of chemistry. Every solid

and every fluid have in consequence been

analysed with the utmost accuracy, and from

bodies, whose elements were found to be the

ame, effects which are altogether different,

are attempted to be explained.

If I proceed to detail the opinions which areentertained

respecting the function of the organs

which subserve the office of meliorating

the blood from the deterioration which it constantly

sustains, they will be found most erroneous

and contradictory. Instead of considering

the lungs, (as I conceive they ought to be

considered,) as much organs of digestion as the

stomach itself, the one acting upon, and digesting

particular kinds of air, as much as the other

is known to do particular kinds of food ; that

while the latter restores the waste which the

blood sustains in point of quantity, the former

meliorates it in point of quality; and, by the

PHYSIOLOGY OF ORGANIC LIFE. 125

iinited power of both, it is preserved in a state

fitted to answer the ends for which it is designed

; instead, however, of supposing that

the lungs act upon the air, it is supposed that

it is the air which acts upon the lungs, and,

like the action of the food upon the stomach,

that it is a chemical, not a living act.

Instead of separating the function of respiration

in general, as it ought to” be, into inspiration

by which air is received into the lungs into

digestion, by which particular portions of it are

separated from the rest, and received into the

blood for its melioration and support ; and,

finally, into expiration, by which the residuary

and feculent parts are expelled from the system:

the process of respiration, on the contrary,

is confined to inspiration and expiration

only. I shall not dwell upon the multitude of

cruel experiments, which have been made on

cats and dogs, in order to ascertain the quality

of the different materials which are received

and expelled : in spite of all the means which

bave been employed, these chemical physiologists

continue at variance, and have not yet

settled whether oxygen air, or caloric, is obsorbed.

The late experiments made, without

the aid of torture, by two eminent chemists,

MESSRS. ALLEN and PEPYS, upon this subject,

would seem to disprove all the experiments

that have been made before : they go to show

126 PHYSIOLOGY OF ORGANIC LIFE.

that although much carbonic air is expired,

little or nothing- is taken in ; however high the

authority certainly is, whence this opinion

has come, I, nevertheless, consider the actual

change of color, and of consistence, from black

and thick, to red and liquid, which the blood

undergoes as it passes from the heart through

the pulmonary artery, and through the lungs

to the pulmonary veins, is far more decisive

than any chemical experiments performed on

the air out of the body can disprove ; that independently

of what is expelled, a considerable

quantity of matter is, nevertheless, received,

the quality of which it is not worth a

rush to ascertain ; the experiments made by

Mr. HUNTER, Dr. GOODWIN, &c &c. are decisive

on this point.

Equally at variance, are physiologists, with

respect to the manner in which the matter acted

upon by the lungs is conveyed ‘into the blood.

Instead of supposing that the parts of the air

which have been separated from the whole, are

absorbed by the extremity of the pulmonary

veins, as the nutritious matter which the placenta

furnishes for the support of the foetus is

unquestionably absorbed by the extremities of

the umbilical veins, or as the chyle by the

chylous (lacteal) vessels : it is generally supposed

that the air forces its way into the blood

by the most unnatural means ; not through the

PHYSIOLOGY OF ORGANIC LIFE. 127

medium of open orifices which are greedy to

receive it, but through the solid and impenetrable

sides of the vessels themselves. A construction

of vessels which would permit the

access of air through, would evidently admit

the egress of it also. The assertion has been

disproved by experiments which were made to

support this opinion. The jugular vein of rabbits

has been exposed, and oxygen air by

means of a blowpipe, has been directed upon

it, without producing any sensible alteration

on the blood that flowred through it; on removing,

however, the external coat of the vessel,

it was supposed that the color of the blood

then underwent some change, and became

more florid than before: a false fact such as

this, will not, I trust, give any weight to such

an opinion, more especially when we reflect

that the actual and palpable existence of air in

the blood, is immediately attended with convulsions,

and with death. It is the mode which

many farriers now adopt to kill horses. By

means of a blowpipe they introduce a small

quantity of air into the jugular vein, which, after

a few struggles, puts an end to the animal’s

existence.

Although chemical physiologists have been

undecided with respect to the quality of the

matter which has been received from the lungs

into the blood, they have been, generally speak1S8

PHYSIOLOGY OF ORGANIC LIFE.

ing, unanimous m opinion, that it was the

source and the cause of animal heat, ff such

an hypothesis were true, it must, as a consequence,

follow, that the temperature of the

blood must be higher at the point near which it

is received* than in the most remote parts from

if

; find that the blood on the left side of the

heart ought, in that case, to be hotter than the

blood on the right side of it. The fact, however,

is precisely the reverse. The experiments

made by Mr. A. COOPER, (and there is

no man more able, or more to be depended

upon,) show, in a manner the most decisive,

that the blood on the right side of the heart, at

the greatest possible distance whence the matter

of heat is supposed to be received, was from

two to three degrees hotter than the blood on

the left side, the nearest point to the supposed

source of heat. If the hypothesis, therefore, is

admitted to be true, we must also admit the

absurdity, that a body is heated to a greater

degree when situated at a great distance from

a fire, than when it is placed close to it.

How the gaseous matter received from the

lungs, acts upon the blood, except by changing

its color and consistency, is as unknown at

present, as the operation of medicine upon the

stomach. The causa operandi of medicine ip

altogether unknown, and the modus operandi is

only acquired by experience, obtained through

PHVSIOLOGY OP ORGANIC LlFE. 129

the medium of observation, and of accident.

The best physician existing can no more tell

the cause why tartarised antimony has an emetic,

or the sulphate of magnesia, a cathartic

effect, than the most ignorant nurse living 5

much less, (if total ignorance would admit of

degrees,) how specific remedies produce specific

effects, in curing particular complaints.

Let it not, therefore, be arrogantly asserted,

that there is any science in pathology, or in

the practice of medicine ; it is absolute

quackery.*

The ignorance which exists respecting the

actual functions of the organs which meliorate

the blood in point of quality* extends to those

* I wish, however, to be clearly understood ; I speak of the

practice of medicine as a science, not as an art . The observations

and experience of intelligent and sensible men have been

the means of employing the different remedies to the greatest

advantage, which relieve and cure different complaints ; and,

the man who has the greatest experience, and who has the best

capacity to make observation on the progress of the different

symptoms of the same disease, and to compare different diseases

with each other, is, unquestionably, the man who is most

likely to constitute the best physician. With respect to surgery,

there is, perhaps, no branch ofart that has undergone,

within the last thirty years, greater improvements, not only

as to the instruments employed, but also in the mode of

using them ; and the sufferings of mankind have, in consequence,

been greatly mitigated ; these observations may, i

some degree, be applied to the obstetric art also.

K

130 PHYSIOLOGY OF ORGANIC LIFE.

which supply the waste it sustains in point of

quantity also.

With respect to saliva, instead of considering

it as an auxiliary to the teeth, in acting upon

the food ; it is, for the most part, viewed as a

mere mucous fluid, intended to lubricate the

surface of the mouth. The saliva, however,

seems destined to a higher office. While the food

is broken down, with respect to mass, by the mechanical

action of the teeth, the saliva is intended

to assist the teeth in comminuting those parts

into smaller particles. It is one of the first

agents employed to eliminate the specific and

chemical qualities which the food contains ; it

bereaves acids of their acidity; alkalies of their

acrimony ; and, to a certain and limited extent,

blunts the asperity of both; rendering the

different articles of food bland and mild, as a

preparatory step to the action, in the stomach,

which the food is to undergo.

The various facts which were produced by

Mr. HUNTER, and which have been multiplied

without end, by others, prove, in a manner the

most decisive, that the change which the food

undergoes in the stomach, from a dead to a

living state, is a living, not a chemical act. Although

all agree that the gastric juice is the

agent, by the energy of which the process is

accomplished, with the exception of a few, the

effect is referred to a chemical, not to a living

PHYSIOlOGY OF ORGANIC LIFE. 131

cause. With as much rationality might we

refer to death, the cause of life ; to organic

action, the source of organisation ; or assert

that the feculent matter in the rectum, is the

seat of chylification. It is scarcely necessary

for me to expatiate on the folly of these opinions.

They tend to revive the exploded doctrine

of M’BRiDE, that digestion is a process of

fermentation and putrefaction, and that the

same means are employed, in the animated

system, to bring dead matter into a living state,

as are employed to decompose and reduce

living matter, to one dead arid common. The

gastric juice, like the other fluids, has been analysed

also, but instead of manifesting any chemical

properties to which its power can be referred,

it has been found to be destitute of

them ; it is neither acid nor alkalescent, but

perfectly insipid and inoffensive. Is it, I would

ask, reasonable to assert that a fluid such as

this, which appears to be destitute of all chemical

quality whatever, nevertheless acts by

chemical power ?

The same errors exist respecting the agency

of the means, by which a separation of the chylous

from the feculent parts of the chyme is

effected, after it has passed from the stomach

into the intestinal canal ; although the first portion

of the canal is evidently constructed with a

view to retard the passage of the chyme through

K 2

132 PHYSIOLOGY OF ORGANIC LIFE.

it, it is generally believed that the bile which

the liver secretes, is merely intended to accelerate

its expulsion/ It is far otherwise ; the

internal surface of the canal is increased, to a

very considerable extent, by means of a number

of ridges, or folds, which, at first, are nearly

concentric to each other, but which gradually

acquire a diagonal direction. Since, then, the

alimentary canal is constructed with a view to

retard the motion of the food through the first

part of its course it is most unreasonable to

suppose, that the real and direct intention of

the hepatic system, is to hasten its expulsion.

If this were the case, instead of harmony,

there would be perpetual warfare between

both : the retarding construction of the intestines

would always tend to prevent, what the

bile was designed to accelerate, and the ductus

communis, in such a case, instead of having its

orifice in the duodenum, ought to have it in the

rectum. Those who can reconcile this warfare

of parts that are dependent upon each other,

have very inadequate notions of the symmetry

that pervades the whole of the system, and of

the harmony that exists between the parts of

which it is composed. So far from supposing

that the primary use of bile is intended to defeat

the end for which the intestinal, (or the

chylous canal, as it ought more properly to be

called,) is so peculiarly constructed ; I think it

PHYSIOLOGY OF ORGANIC LIFE. 133

far more reasonable to conclude, that it is intended

to harmonise with it; and that the bile

instead of acting by its resin, and its alkali, as

an active purgative, is intended, in the first instance,

to separate the chylous, from the feculent

parts of the chyme ; producing a precipitation

of the one, and afterwards assists the

expulsion of the other, conformably to experiments

which have been made to ascertain

the point.

With respect to the pancreas, or sweetbread,

although it secretes a fluid of a quality bland

and mild, somewhat similar in its prpperties to

saliva, and which, probably, co-operates in accomplishing

the same purpose as the bile from

the liver ; the specific determinate use to which

this fluid subserves, continues, to the best experimentalist,

a perfect mystery.

The same uncertainty prevails respecting

the use of the spleen. The well-known fact,

that it has been altogether absent in animals

which, in general, have one; and that it has

been extirpated without producing any violent

shock to the Constitution, led to the supposition

that it was of little or no use. Dr. STUKELEY,

seventy years ago, in his Gulstonian Lecture,

traced the connexion which subsists between

the spleen and the stomach, as well as

between the other abdominal viscera ; and, from

a very scientific mode of investigation, was led

134 PHYSIOLOGY OF ORGANIC LIFE.

to conclude, that the spleen was designed to

assist the stomach in the process of digestion.

These opinions of Dr. STUKELEY, have since received

some confirmation from experiments made

by Dr. HAIGHTON, the respectable lecturer on

physiology, at Guy’s Hospital. The Doctor was

led to conclude, that when the stomach was distended

and full, the pressure which the spleen

is made, in consequence, to undergo, not only

prevents the passage of the blood through that

organ, but that it actually does produce an increased

accumulation, in the vessels with which

the stomach, and the pancreas, are supplied.

Greatly as I respect Dr. HAKJHTON’S talents

and industry, there are many objections to his

experiments upon this subject ; and, the fact

that, in some animals, the situation of the stomach

and the spleen are so remote that they

cannot come in contact, may probably appear

an insuperable objection to his hypothesis.

Mr. HOME, who holds the first rank in his profession,

and who must be considered very high

authority also, from different experiments which

he made on dogs, is of opinion, that the food

from the stomach undergoes some change in

the spleen, not through the medium of the absorbent

vessels, but by some unknown mode

of communication. After tying the pyloric extremity

of the stomach, and injecting into that

organ, infusions of madder and of rhubarb,

PHYSIOLOGY OF ORGANIC LIFE. 135

and killing the animal, he found that the cells

of the spleen, (particularly at the great end of

it,) were very large and distinct ; on macerating

a portion of it in ten drachms of water, and

testing it by an alkali, he found that it gave out

a reddish-brown color in the centre, and no

where else. A similar portion of the liver was

treated in the same manner, and an alkali was

added to the strained liquor, but no such

change in it was produced. I mention these

opinions in order to show how little is known

upon the subject.

The same confusion exists with respect to

the lacteal (or chylous) vessels ; those vessels

which arising with open mouths from the folds

of the intestines, absorb the chyle, or digested

aliment, after it has been depurated from its

feculent portions, and convey it to the mass of

blood, in order that the waste which it undergoes,

may be restored. The mode by which

the absorption is accomplished continues an

object of disputation; instead of supposing

that it is performed by a living power in the

parts, analogous to the suction of a leech, or even

of an infant at the breast ; by many it is considered,

an inanimate act, similar to the raising

different fluids in narrow tubes, by what is

called capillary attraction, Although the lacteal

(chylous) resemble the lymphatic vessels,

in the office of absorption, the substances on

136 PHYSIOLOGY OF ORGANIC LIFE.

which they act, are, in their nature, totally

different. While the former convey to the

blood the nutritious matter which the stomach

had assimilated; the latter, on the contrary,

are designed to remove and carry away those

pprts of the system which are worn out, and

which exisj; in a perishing and dying state ;

the former may be compared to cooks, who

constantly afford to the blood a supply, the

other to scavengers, who take away the dilapidated

parts of the system.

It is in obedience to the diversity in the end

to which each system is subservient, that there

exists a diversity of power between them at

(different periods of life ;

i infancy and youth,

while the system is in a state of progression

jin4 growth, the lacteals are large, and the

lymphatics comparatively small. At the middle

periods of life, when the system has attained

the acme of perfection, both systems are, as it

were, balanced ; in old age, on the contrary,

when emaciation and decrease take place, the

balance between them is altogether overturned,

aiicl both scales are put into one ; the lacteals

become weaker and smaller, while the lymphatics

increase in magnitude and strength. IncJ

of contemplating the action of these ves-

, with relation to the separate functions

which they are designed to perform, both are

generally confounded together; while the fpiv

PHYSIOLOGY OF ORGANIC LIFE. 137

nier carry materiaTs to the blood, to supply the

waste which it suffers the latter receive from

the system the parts which are wasted, or

which have accomplished the purpose for

which they were enlarged. In no organ is this

office more striking, than in the uterus. Before

gestation, the lymphatics of that organ are remarkably

small and thready ; after parturition,

they immediately increase in size, and have

often been seen as large as the quill of a

goose : it is through their agency that the different

parts of the system, that are either super^

fluons, or diseased, are removed ; diminishing

the fabric of the whole by the parts which they

absorb, and often destroying the form itself.

Notwithstanding these avowed purposes for

which the lymphatics are designed, the opinion

which was first broached by Mr. HUNTER,

soon after they were discovered, that they were

the modellers of our frame, continues to be preserved.

Instead ofbeing modellers, they form the

agents only,*

1

by which the dilapidation of the system

is accomplished. If the power of these ves-

* The pig which had remained under the ruins of the cliff

which fell in at Dover, for the period of five months, was reduced

in weight, by the activity of these vessels, for the most

part, from eight score, to thirty-six pounds ; that is, he had

lost in weight 124 pounds.

138 PHYSIOLOGY OF ORGANIC LIFE.

sels, at the first periods of life, were equal to

those of the chylous, and secretory, the system

would remain stationary in infancy, as it

does at the period of manhood, without ever

arriving at it ; and, on the contrary, if the actions

of these vessels were not greater in old

age, than in infancy and manhood, there would

scarcely be in the system any diminution in its

size ; the whole would be like an evergreen, never,

perhaps, liable to perish or decay. But,

alas ! this period of decay does arrive ; it is

brought on by the loss of balance, between the

vessels subservient to the growth, and to the

decrease of the system. In the common course

of nature, the change is gradual and imperceptible,

but it, nevertheless, is constant and uninterrupted.

The arteries, with relation to the

veins, are small in size ; and the veins, on the

contrary, are large with relation to the arteries

; all, all is waste, and no supply : the

power whick the different organs originally

possessed, of imparting any vital energy to the

different substances that are applied to them,

and even of retaining their own, becomes lost,

and a total abolition of all sense and sensation,

of all consciousness and voluntary motion,

ensues. The different muscles, volun.

tary involuntary and mixed, whose actions depended

on the energy they ought to receive

from the matter contained within the cavity

PHYSIOLOGY OF ORGANIC LIFE. 139

of the spine and cranium, cease to act; and the

whole of the system becomes in the most perfect

state of paralysis that can be conceived, or

described; and that condition of the system is

induced, which is known under the appellation

of death.

It is not, however, the mere separation of

the fruit from the tree on which it grew; or,

the mere division of the orange, or the apple,

into parts, which constitutes death ; although

this separation diminishes, it does not destroy

its living and preservative property ; the

living property of different parts of animals,

is proved to exist for some time after they

have been separated from the system, to which

they belonged ;

it is proved to exist in teeth,

from the success which attends their transplantation

; in the blood, by its transfusion from

one animal to another; and in eggs, by their

evolution. The heart of a turtle, or of a frog,

will retain its irritability, and power of contraction,

for several days after it has been completely

torn out of the system, to which it belonged.

The whole external surface of the

animal is often frozen nearly to a state of petrifaction,

and, nevertheless, continues to

retain its preservative and living powers.

Under various circumstances, the different

organs are found to recover their particular

organic actions, as the vernal season advances ;

140 PHYSIOLOGY OF ORGANIC LIFE.

and the whole animal becomes as vivacious as

before.

If we are to credit the accounts published by

the HUMANE SOCIETY, organic action has been

resuscitated after it has been suspended for many

hours, and while the following torpid state was

present, the rigid limb the clay-cold skin

the silent pulse the breathless lip- the livid

cheek the fallen jaw the pinched nostril

the fixed and glassy $ye. CELSUS, and other

venerable authors, have recorded various instances,

in which organic action had been recovered,

after it had been suspended for several

days. Without trusting to human testimony

alone, we have also that which is divine; I

mean only what respects the distinction which

exists between apparent, and absolute, death ;

the recovery of action in all the cases related,

was miraculous effected by the almighty power

alone of the great Author of our salvation.

I might state the case of Jairus’s daughter,

mentioned by ST. LUKE. She was twelve years

old when Jairus first applied to Jesus :

” she

lay a dying:” but soon after she was so dead,

that the ruler of the synagogue told him,

” not

to trouble his Master:” all, therefore, wept and

bewailed her ; but, Jesus said,

Weep not, she

is not dead but sleepeth” They laughed him to

scorn, knowing that she was dead : and he put

them all out, and took her by the hand, saying,

PHYSIOLOGY OF ORGANIC L1F&. J41

” Maid arise;’ and her spirit came again, and

she arose straightway. Here then was a case

of suspension of all organic action, while the

power of preservation subsisted. We have

similar instances related in the book of Kings,

of the prophet Elijah reviving the widow’s son;

and of our Lord himself, when he reanimated

the son of Nain’s widow. On the contrary,

when the evangelist speaks of death, he makes

a very evident distinction between the signs

by which it is characterised, and those that attend

suspended animation only; as in the case of

Lazarus, who had been dead four days, where it

is said,

” that he stinketh” Here then we find, in

scripture itself, an evident distinction between

the mere suspension of organic action, while

the general properties of preservation continue

to subsist, and the total deprivation of life,

with the consequent loss of all organic power.

Death, therefore, constitutes that intermediate

state which exists, when the powers of life

are displayed in organic action, and the total

decomposition of the whole machine into its

constituent parts. However different the means

may be, by which death and decompostion are

effected, the end is certainly the same in

all. There are, it is true, various means by

which the actions of life are supported, as well

as various means, by which those actions can

be suspended, and annihilated. Every indivi142

PHYSIOLOGY OF ORGANIC LIFE,

dual system, however, has one life only, not

many lives ; so one living system can have one

death only, not many deaths ; however different

the modes may be by which that death may

be endured. Varied and prolonged as it may

be in mode and in time, it is the fate allotted

to all generated beings ; and to which they

are doomed : -they are essentially transient

and frail, and subsist in a constant state of

progression, perfection, decomposition, and

decay.

Putrefaction and fermentation are the means

by which the bond of animal and vegetable

matter becomes loosened, and broken ; and the

whole of the system develated from an organised,

to a disorganised state; the parts

that were fixed become volatile ; such as

were inodorous, become offensive to the olfactory

sense ; such as were insipid, become

sapid ; those that were homogeneous, become

heterogeneous ; and, finally, resolved back

from a dead, to a common state. Putrefaction

and fermentation, in fact, have the same relation

to dissolution, that the act of digestion has

to life ; while the act of digestion prepares

common and inanimate matter, and fits it to

receive the energy of the living principle to

which it is applied; putrefaction and fermentation,

on the contrary, bring back dead

matter to a common state : it is the last and

PHYSIOLOGY OF ORGANIC LIFE. 143

ultimate change, which it sus-tains, and which

alone virtually, and in fact, constitutes dissolutionnot

a suspension of organic action only,

but a total decomposition from its former state

of union.

The flesh and blood of a horse, or of an

ass ; of a monkey, or of a man ; of a materialist,

or of a philosopher, will yield the

same materials by decomposition. There may,

perhaps, be a greater quantity of ammonia in

the one, than in the other ; but as this difference

is frequently found to exist in the analysis

of the flesh of different men, no inference from

thence can be drawn, that the animal matter of

which these different beings are composed, is essentially

different. Decomposition is, therefore,

the last change they sustain, in order to reduce

the different parts from a living to a dead state,

that they may be ultimately converted into a

common one. The chair on which I sit the

paper on which I write and the pen with

which I am writing, in common with the

organic remains of the animal and vegetable

kingdom as well as the exuvise of both, constitute

dead matter.

After having stated what I conceive dead

matter actually to be ; to understand what it

is not, must be most obvious. Dead matter

forms no part whatever of the organs which

subserve to the functions of animals, or of ve144

PHYSIOLOGY OF ORGANIC LIFE.

getables ;

it neither exists in bones, or iti

muscles ; in blood, or in the different vessels ;

in the organs, or in the fluids which they

secrete, to answer a living purpose. Neither does

dead matter exist in any part of the elementary,

or common matter, of which the universe is

composed : it does not exist in solid or liquid

matter ; not in earth, or in water ; in fire, or

in snow ; in air, or in light so long as these

bodies subsist in a common state ; neither are

these bodies susceptible of undergoing the

spontaneous decomposition which dead matter

suffers.

It is by tracing the system of nature, from

animated beings, to such as are inanimate ;

from the agent, to the patient ; from the cause

to the infinity of its effects ; from things composite,

to things simple ; that we are enabled

ultimately to arrive, at the contemplation of

that primary elementary matter, of which the

whole of the universe is composed and filled.

Mr. HARRIS, the learned author of Hermes,

very accurately defines this matter, to be

that elementary constituent in composite substances,

which appertains, in common, to

them all, without distinguishing those composite

substances from one another ; for, although

the matter of which the ark, and the

ship the anvil and the saw, are formed,

may be, in kind, severally the same, and apPHYSIOLOGY

OF ORGANIC LIFE. 146

pertain, in common, to them all ; it, nevertheless,

does not distinguish the one from the

other. The one is distinguished from the

other, by the energy of the formative power

which converts matter, the same in kind, into

instruments totally different, this power does

not reside in the matter which is employed,

it proceeds, in them, from the efficacy of the

artist, by which the matter was modelled, and

from the power of the living principle by which

it was organised. It is this condition of matter

to which Mr. HARRIS has given the appellation

of primary matter the v^\ w^ul* of the

antients ; the substratum of which all composite

substances ar.e constituted, without in>

parting to them any distinguishing character

whatever. Common matter, therefore, with

relation to vitality, appears to be divisible and

penetrable in all its parts imbecil and inert:

to subsist, in fact, in a state of universal privation,

extension alone exeepted.

CHAPTER VII.

ON THE ELEMENTARY PROPERTIES OF COMMON

MATTER IN GENERAL.

SECTION I.

On the Matter of Light.

AFTER having detailed the state of deprivation

in which matter, in general, exists, with relation

to the principle of vitality, and the properties

which it has acquired through its energy it

will be easy to comprehend the nature of its

existence, after it has lost the participation of

Jife which it had received, and when it has

been finally and completely resolved back to

its common and elementary state, whether of a

fluid, or of a solid kind. Instead of contemplating

the nature of extension, and of bulk,

which matter, in general, possesses ; by virtue

of which it has the capacity, or aptitude, to be

acted upon by the agency of external means,

PROPERTIES OF MATTER. 147

we rather search for the properties which external

means have produced upon it; and,

instead of separating, confoundfigure and extension

together. It will, however, appear,

that if matter, whether solid or fluid, while it

subsists in a common state, possessed, originally

and essentially, any of those secondary

qualities that are ascribed to it of figure, or of

color; it would, in that case, be altogether unfit

to answer the ends for which it was especially

designed : it could no more subserve the pur-%

poses for which it is employed by animated

beings, (for whose use, it is reasonable to presume,

it was intended,) than matter convey

nourishment to the living system, whilst it resisted

the digestive power of the stomach.

This state of original deprivation of all secondary

quality in solid matter, is equally

referrible to liquid ; to that element \vhich may

be considered as constituting the principal source

and support of fluidity in general. If water

possessed flavor together with fluidity, it would,

in such a case, be the flavor of the water that

was tasted, and not the flavor of the substance

which the water was intended to dissolve, or to

support : if water were salt or sour bitter or

sweet sapid, instead of being insipid altogether,

those secondary qualities would constantly

manifest themselves, and the quality of

the receiver would always adulterate and obli-

L2

148 ‘ ELEMENTARY PROPERTIES

terate the quality of the thing received. If we

extend our views to air and light, we shall find

that, although each of these bodies possesses

properties of its own, which are Inseparable

from the extension which they contain, that

they are, nevertheless, originally destitute 6f a

variety of thos^ secondary qualities which are

‘often ascribed to them, but which they afterwards

factitiously obtain. With respect to

fcir, it bears the same relation to sound, that

water does to flavor ; or that the block does

to figure ; if air possessed any particular

^sound of its own, that sound, like the figure

upon the canvas, would constantly manifest

itself; either, when it was impelled by mechanical

means through musical instruments in

general, or, through the vocal organs in particular

; instead of harmony, discord must be

produced. Air possessing, however, the primary

and essential attributes of expansibility

Blone, it has the power to expand, and the

capacity to be compressed ; to be modulated

atid harmonised by the energy resident in the

Organs of speech ; and, by their instrumentality

language is produced. The satne observations

equally apply with respect to resistance. If the

medium of air, through which the rays cf light

are conveyed, instead of being diaphanous

and permeable, were turbid and colored ; the

rays of light, instead of being transmitted,

OP COMMON HATTER. 149

would be arrested by the air, as they are found

to be, by the opacity of a cloud, or of a fog;

and if the air were colored, the light in its

passage through it, would be constantly tinged

and dyed by the color of the medium. That

this would be the case, is clearjy demonstrated,

by the effect which is produced on the rays of

light when they pass through the medium of

glasses stained with different colors ; the color

of the glass is always found to stain the rays of

light, and convey to the eye its particular color

: through a green glass, a body looks

green ; through a red glass, it looks red ; and

the influence which a jaundiced eye possesses,

of rendering bodies seen by it to appear yellow,

has been often noticed.*

The different states of the medium which I

have described, may be considered as unnatural

and morbid ; arising from the union and

diffusion of different bodies, which have insinuated

themselves into it. If the colored state

of the medium through which objects are beheld,

produces these unnatural consequences,

*

Although I have known this sensation occasionally to

happen, it is not generally the case ; when it does happen, it

is only in those extreme cases ofjaundice, when a large quantity

of bile has been absorbed, and conveyed into the blood ;

and incorporated to a considerable degree, with the cornea

and the humors of the eye.

150 ELEMENTARY PROPERTIES

how much more must these unnatural consequences

be produced, if the rays of light are

themselves colored originally and essentially!

If, in fact, the light which proceeds from

the sun to the earth, consists, as Sin ISAAC

NEWTON has asserted, (and as it is, at this time,

generally believed,) of seven colors, which, possessing

different degrees of refrangibility, may,

in consequence, be separated from each other,

by means of a prism, and seen to display the

several colors of red orange yellowgreen

bfae! indigo and violet ; that these seven

different colors are original and simple ; and

that all the colors in the world, either consist

of these simple colors, or of compounds, formed

out of them, mixed together in different proportions.

If this hypothesis were true, that the rays of

the sun, the pure matter of light, were colored,

the inevitable consequence would be, that all

the bodies which were conveyed to our organs

of vision, would be constantly tinctured and

dyed by the particular colors of those rays.

It would not be the specific and identical color

of the object itself, that we should behold, but

the individual colors of the rays alone. Thai

this would be the fact, may be proved in a

manner the most satisfactory and decisive. If

a beam of light be separated by a prism, into

the seven prismatic colors, and any substance

OF COMMON MATTER. 151

placed in the image formed by each separate

ray, the color of the substance always participates

the color to which it may have been

exposed ; in the red ray, the substance appears

red ; in the orange ray, it assumes an orange

color ; in the green, a green color ; and, so on

of the rest; instead of the infinite variety of

colors, by which we behold every particle of

matter characterised, color would be entirely

limited and confined to the prismatic only ; to

seven, as SIR I. NEWTON supposed, or even

to three, as they are now reduced ; or, to the

modification which might be formed, in consequence

of their union in different proportions*

The result would be, the production of some

color, varying, it is true, in appearance, from the

separate color of each individual ray, but altogether

different from the specific tinge, or dye,

which I contend the ray of light has received, by

uniting with the body on which it falls, and from

which it was reflected ; conveying with it the

tinge, or dye, as it were, of the substance, to

the organs of vision. The state of deprivation

which the sun is in, respecting color, is equalJy

referrible to fire.

Although the sun has been generally considered

the original source whence fire was

derived ; every fact of which we are in possession,

when properly examined, will be found to

militate against this opinion. If the sun is a

globe of fire, it must, in every respect, be situ152

ELEMENTARY PROPERTIES

ated with relation to surrounding objects i*

general, and to this world in particular ; in a

manner similar and analogous to any collected

mass of sublunary fire : its power may differ in

intensity, but its influence must be the same ;

so far, however, from the effects which flow

from both, being one and the same, they are

found to be totally different from each other.

It may be considered as a general truth, that

these effects continue to increase in a progressive

degree, in proportion as the fire is approached,

and that its maximum of power is

more especially displayed, when foreign bodies

are in immediate contact with it With respect

to the sun, the effects are altogether different ;

if the sun is a globe of fire, it must, as a

consequence, follow, that the degree of heat

and of expansion which it excites, ought uniformly

and progressively to increase, not only

in proportion to its proximity to us, but more

especially, according to the purity and rarity of

the medium through which the rays of the sun

are transmitted. Although the temperature

varies, in an infinite degree, in different latitudes,

from the line of the equator to the poles, when

the temperature is measured on the plain surface:

at the highest point of elevation, on the

contrary, a generalauniformity is found to exist;

so far from the temperature increasing as we

ascend, the very reverse takes place; the tempeOF

COMMON MATTER. 153

rature perpetually decreases to such a degree,

that the climate is altogether unfit for animal or

vegetable life, and the intensity of it can only be

apprehended, by the vast coverings ofsnow and

of ice with which the summits of the most lofty

mountains, in all parts of the world, whether

situated at the polar or meridional regions, are

everlastingly coated. That this is the fact, will

appear, if the temperature of different latitudes,

at the same degree of altitude, be compared with

each other. Although the highest mountains of

this island may be considered as mere dwarfs,

when compared to those of the continent, in point

of density and elevation, the decrease oftemperature

is, nevertheless, very perceptible with the

increase of elevation ; while the thermometer

was at 63. last August, at the base of Skiddaw,

the mercury gradually fell, in ascending towards

the summit of that mountain, as low as 34*.

This great diminution of temperature from the

base to the summit, is more especially found to

subsist in Mount ^Etna Vesuvius and Olympus

the peak of Teneriffe the Alps and Appenines

the Andes and Cordilleras those

gigantic mountains that are surrounded by

burning sands, and situated at the equator ;

whose position, with respect to the incident solar

ray, is vertical ; whose elevation is so high, that

the rarity of the atmospheric medium, through

which the rays are transmitted, is, in a great

154 ELEMENTARY PROPERTIES

degree, free from atmospheric pollution ; and is

as incapable of opposing to them resistance, as

it is to bereave them of igneous power. If the

sun, therefore, were a globe of fire, instead of

the summit of these mountains being everlastingly

coated with ice and snow, neither the one

nor the other ought ever to be seen ; and, instead

of the temperature being higher at the bottom

of a mountain than at the top, it ought to be

higher at the top than at the bottom.

We are, therefore, driven to the necessity of

concluding, that, notwithstanding the mixture

and opacity of the medium, in which we exist,

is involved ; that there subsist in it, rays of light,

that are neither hot nor cold fire nor ice

black nor white yellow nor green orange

nor red purple nor violet but that are transparent

and colorless only ; that are as colorless

as air is speechless as much as water is tasteless,

or, as solid matter is self-motive ; but

that are destitute of every essential and original

quality, extension and motion alone excepted.

Consequently, it may be presumed, that the

sun itself as the parent whence the rays of pure

light proceed, is a globe of light only.

If the rays of the sun were, inherently, to

possess any other attributes than those of extension

and motion, the effect would be different

from its cause ; one of the fundamental laws of

nature would be subverted arid destroyed ; and,

OF COMMON MATTER. 155

a consequent inversion of principle would ensue;

instead of elementary and causal bodies

producing effects according to their own nature;

instead of the effects being secondarily, what

the cause is, primarily, no correspondence or dependence

would exist between the effect and

the cause. The eye, therefore, might as easily

become the organ of hearing, the ear the organ

of seeing, a* for light to possess any other attributes

than those I have already described.

It is far otherwise ; every effect that is produced,

is not only the result of a power resident in

a cause, but in every case, and under every

possible circumstance, the power of the cause

transcends the power of the effect that flows

from it. The element of light, therefore, subsisting

in the sun, is as superior, in brilliancy,

to its rays, as the purest light of the brighest

day, is superior, in brilliancy, to light obtained

from those bodies by which it is exhibited and

evolved; the rays of the sun, therefore, continually

lose part of their purity, as they descend

to the earth,

SECTION II.

Oti the Source and mechanical Power of Light.

THAT the sun is the principal source, the

fountain and the reservoir, whence the mat156

ELEMENTARY PROPERTIES

ter of light originates and proceeds ; appears,

I may be allowed to say, a self-evident truth.

It is proved, positively, by the illumination

which we enjoy, and by the facility which we, in

consequence, possess, of beholding surrounding

objects, when it is present to our view. It is

proved, negatively, by the total state of obscurity

and of darkness, in which we are involved,

when in the course of planetary revolution,

we are deprived of the benefit of the sun’s

rays ; with the exception, perhaps, of the light

which might flow from the planets, and from other

bodies, which have, either directly or indirectly,

received its influence, the world, at large,

would be involved in darkness the most impenetrable

and profound. It is an indelible truth,

that the region which we inhabit r-the world in

which we exist every particle of matter of

which it is composed with respect to light,

subsists in a state of total and absolute privation;

there is no light originating in it, or

belonging to it ; no light, but rather darkness

visible ; and the light, in short, which we enjoy,

is not native, but exotic ; not inherent in any

part of the system to which we belong, but

altogether derived from the planetary system

in general, and the sun in particular.

Splendid and brilliant as is this attribute, of

exciting the sensation of illumination on the

organs of vision, with which animated beings

OF COMMON MATTER. 157

are endowed, it must, nevertheless, be admitted,

that the velocity with which it moves, and

the extreme subtilty and exility of which its

particles are constituted, are equally deserving

our admiration and astonishment. Although

these attributes, from the very nature of them,

might be expected to evade the researches of the

most learned : the attentive observation of the

ingenious have, nevertheless, in some measure,

succeeded in ascertaining the degrees of the

one, as well as of the other. Among the most

illustrious of these, may be mentioned Dr.

BRADLEY, REAUMUR, and CASSINI ; the data

on which they proceeded, with respect to the

motion of light, were founded on the eclipses,

which the satellites or moons of the planet

Jupiter, undergo. By observation, they found

that the eclipses of these satellites appeared, in

fact, sooner than they ought, by hypothesis, to do,

when Jupiter was nearer to the earth ; and later,

When that planet was on the farthest side of her

orbit; or, in other words, that the time when

these eclipses appeared, was always influenced

by the degree of distance. By observations, such

as these, they were enabled to show, that

although the motion of the solar rays, is not

instantaneous, but progressive it, nevertheless,

flows with the astonishing velocity of 200,000

miles in every second of time; so that, admitting

the sun to be 95,513,794 English miles

158 ELEMENTARY PROPERTIES

distant from this earth, the rays which issue

from the sun reach the surface here below, in

the short space of 8 minutes, llg seconds of

time ; a distance which could not be traversed

by the swiftest ball that was ever fired out of

the largest cannon, in less time than thirty-two

years ; admitting, what is impossible, that it

continues to preserve its initial velocity of one

mile per second of time.

If the solar rays possessed a correspondent

degree of density or of motive power, the combined

effect the momentum, (i.

  1. the quantity

and velocity compounded together,) would produce

an impulse which would be capable of

overcoming the resistance which could be opposed

to them by the densest and hardest

matter, existing in the system of nature. The

eyes of animated beings, in particular, to whose

use the solar rays are more especially designed

to subserve, would be torn asunder, and totally

disorganised; for, as Mr. NICHOLSON very

justly observes, that the momentum of a body

is, as its mass multiplied by its velocity, and

as the solar rays were in the excess of 200,000

to 1 to a cannon ball, it must follow, that, if the

particles of light were equal, in mass, to the

two-millionth part of the smallest grain of sand,

we should be no more able to endure their

impulse, than of the sand when shot pointblank

from a cannon. In illustration of the

OF COMMON MATTER. 159

above opinion, I shall merely quote a passage

from Dr. THOMSON’S valuable System of

Chemistry.

” A 29lb. ball, if thrown from the

hand, makes no impression upon a common

wall, but when discharged from a cannon with

the velocity of 1300 feet in a second of time, it

will then be found to shatter the wall to pieces:

the greater velocity, therefore, with which a

body moves, the greater the effect which it is

capable of producing; consequently, to produce

any effect whatever, by a body however

small, we have only to increase its velocity

sufficiently; and, in order to prevent a body

from producing a given effect, its quantity must

be diminished, in proportion as its velocity is

decreased : now the velocity of light is so great,

that if each of its particles weighed the 1000

part of a grain of sand, its force would be

greater than that of a bullet, discharged from a

musket; were it even the millionth part of a

grain in weight, it would destroy every thing

against which it struck : if it even weighed the

millionth part of that, it would still have a very

sensible force; but how much less must be

the weight of a particle of light, which makes

no sensible impression upon so delicate an organ

as the eye? We are certain then, that no

particle of light, is 1,000,000,000,000th of a

grain ; but were we even to suppose it of that

size, the addition of 900 millions of particles

ELEMENTARY PROPERTIES

to anybody, or their abstraction, would make

no difference of weight capable of being detected

by the most sensible balance ; eery attempt

then to ascertain the accumulation of light in

todies, by changes in their weight, must be hope-

It is owing to this extreme state of exility,

connected with the inherent power of moving,

which the solar rays possess, that they are

enabled to penetrate the internal fabric of

bodies in general, whether diaphonous or opake.

This penetrating power is proved to be possessed

by them, from the impressions which they

excite on our organs of vision ; such is the compact

nature of the comm, or external coat of

the eye, that without this subtilty, the solar

ray, instead of penetrating it, would be arrested

by it, as well as by the other parts of which the

internal fabric of the eye is composed, and

never arrive at the membrane on which the

retina is spread, in which the impression is

deposited, and illumination produced. This

penetrating power is equally proved, by the

illumination which we, in consequence, enjoy

from it, through the medium of different bodies,

and more especially of our windows, insomuch

that glass (which is supposed from its inelasticity

to have its particles most intimately combined

-and compacted) of the most solid quality,

to its passage, neither impediment nor

OF COMMON MATTER. 161

Obstruction. It is further proved by the utter

impossibility which exists, of exhausting- the

solar rays out of a glass receiver, after the other

parts of the atmospheric materials have been

pumped out of it.

Such, indeed, is the extreme subtilty of the

solar rays, that their materiality has been questioned.

I do not mean to range myself under

the banners ofthose who entertain these doubts :

to me it appears, that the materiality of light is

as decisively proved, as the materiality of any

species of matter whatever. The impressions

excited upon the different organs of sense by

external objects, of ice, or of fire, in producing

the sensation of cold or of heat of air upon

the auditory nerves, in exciting the sensation of

sound of volatile bodies upon the olfactory

nerves, in exciting the sensation of odor, &c. &c.

are not more evident and characterised, than

the power which the solar rays possess, of penetrating

the cornea, or external coat of the eye ;

and, after undergoing different modifications,

from the different media through which they

pass, of arriving at the bottom of the eye, on

which the retina is spread, sensation excited,

and illumination produced. The materiality

of the solar rays is proved, by the space which

they fill, and by the illumination which they

excite. It is proved by the facility with whick

M

162 ELEMENTARY PROPERTIES

a beam of solar matter may be reflected and

refracted, and either condensed to a focal

point, or segregated into parts, and each part

produce upon the eye a diversity of impressions.

The materiality of the solar rays is further

proved, by the chemical effects produced

on different bodies which are exposed

to their influence. By their influence, vegetables,

which, in the dark, were pallid and

white, are found to recover their natural verdure

and bloom; by their power, water becomes

gassified ; metals calcified ; and other bodies

modified and changed to such a degree, that

they acquire properties altogether different

from those which they before possessed.

Although the materiality of the solar rays

appears to me an incontrovertible truth, the

mode by which its effects are produced, has

been a source of difference among natural

philosophers. HUYGENS, DES CARTES, and

EULER, considered light to be a subtile fluid,

filling space, and thrown into undulations by the

sun ; which undulations extending themselves

to the eye, render bodies visible. Sir ISAAC

NEWTON, on the contrary, considered light to

be a real substance, consisting of small particles,

which perpetually emanating, in straight

lines, from luminous bodies, and entering the

eye, excite the sensation of vision, or the perOF

COMMON MATTER. 163

ception of those objects whence the light

arose.

It is not surprising that matter .of this subtile

description should have evaded the inquiries

of the most enlightened and attentive ; and,

that they were reduced to the necessity of proceeding

from assumptions, instead of axioms ;

and, of concluding from hypothesis, instead of

demonstration.

The separation of a beam of atmospheric

color, through the medium of the prism, into

seven distinct parts, although not so antient

as the variegated colors, manifested by what is

called the rain-bow, is nevertheless, no modern

discovery. Sir Isaac Newton, in particular, may

be said to have nearly exhausted the subject.

It is, however, to Dr. HERSCHEL, to whom the

merit, unquestionably, belongs, of having separated

the element from the accident, the pure,

colorless light, from the compound and visible

color. As these experiments are detailed, at

large, in the Philosophical Transactions for

the year 1800, have been copied into different

periodical publications, and are well

known ; I shall merely state the general result

of them in this place, and refer the reader

to the original communication. When a prism

is properly adjusted, at a suitable distance from

a sheet of white paper, on which the spectrum,

M 2

ELEMENTARY PROPERTIES

is received, it becomes, as usual, subdivided

into seven different parts ; each of which, possessing

different degrees of refrangibility, becomes,

consequently, separated from each other ;

and the several colors, which are known by the

appellation of prismatic colors, are made visible.

Dr. Herschel found, that by placing a

very sensible thermometer beyond the colored

spectrum, external to the boundary of the red

ray, but still in the line of the spectrum, the

mercury rose much higher, than when it was

exposed to the immediate action of the red ray;

and, on shifting the thermometer still further

from the colored image, the mercury continued

to rise, and did not reach its maximum, until

it was placed half an inch beyond the utmost

extent of the red-colored ray.

By the power of this invisible ray, as it has

been called, but which I shall denominate

colorless, the metallic oxydes were reduced ; and

Dr. WOLLASTON, w7ho has since made a number

of experiments on the same subject, found,

that the muriate of silver was blackened more

rapidly, when exposed to its influence alone,

entirely beyond the reach of the prismatic

spectrum ; and, finally, that this change was

accomplished without the production of any

sensible increase of heat. Had it not been,

indeed, for the sensible phenomena produced

on the thermometer and other bodies, exposed

OF COMMON MATTER. 165

to its power, it would have remained as unknown

to us, at this time, as it vyas to Sir Isaac

Newton, a century ago.

Is it not reasonable to suppose, that it is this

actual and individual ray, which penetrating

bodies the most diaphonous and solid, remains

in them in a latent^ invisible, insensible, and

uncombined state; and afterwards radiates

and issues out of them in a state of combination,

manifesting* the phenomena of color and

of temperature; and, that it is this ray, which

has been so long known under the appellation

of latent heat ?

On an attentive review of the attributes

which seem essentially to belong to light,

I am led to conclude, that in its nature, it is totally

and absolutely different from every other

species of matter, of which we have any knowledge.

The phenomena which it describes decidedly

prove, that it is of a quality sui generis.

Instead of supposing light to be solid, massy,

and impenetrable, I contend, on the contrary,

that every phenomenon which it describes,

shows that it. is the most fluid, the most subtile,

and the most penetrable that can be conceived ;

that, instead of being inert and heavy, it is

essentially active and imponderable. Instead of

moving like the matter belonging to our world,

by a power from without, the solar rays traverse,

with the most incredible velocity, the

166 ELEMENTARY PROPERTIES

wide expanse of the planetary spheres, excit,

ing the sensation of illumination on the optic

organs of animated beings, by a power from

within, inherent and essential ; participating,

in a most eminent degree, the quality of

the cause of which it is the immediate

effect. Instead of supposing that the sun,

as the source of light, actually possesses an

attracting power, the motion of the matter of

light, from the surface of the sun, shows that it

is repulsive, in the greatest degree that the imagination

can conceive. Must it not, indeed, be

obvious to the most common capacity, that if

the sun were an attracting body if a power,

such as this, existed in the sun, as the source

whence the rays proceed, the rays instead

of corning out of it, &ould be attracted by

it, and retained in it ; the solar rays would

be as fixed, arid as immoveable in the body

of the sun, as the solid nucleus of the earth

itself; insomuch, that the universe at large,

would be involved in absolute and utter darkness.

Instead, therefore, of subscribing to the

opinions which have been long entertained,

that all the matter of the universe, is the

same in nature, and in kind ; and that the

diversity of the phenomena, which particular

portions of matter display, proceeds from

the various modifications, and commutatiOF

COMMON MATTER. 107

ons, which the same original particles are

made to undergo I contend, on the contrary,

that the original particles of which

the different elements are constituted, are

originally and essentially different. I contend,

that the solid matter is not only essentially

different from the liquid the earth

from the water both different from air and

fire ; and all of them different from the solar

rays ; and as a consequence of the diversity

in the attributes of each, that it is most

unphilosophical, and unscientific, to ascribe

the phenomena, or effects, which each of them

severally displays, to the operation of one

and the same law. Finally, it may be presumed,

that the various observations which

have been made, by Dr. HERSCHEL, and other

celebrated astronomers, on the nature of the

dark and opake matter, of which the body of

the sun is supposed to be composed, are optical

errors, from the imperfection, and insufficiency,

of the instruments employed ; that these

spots, instead of constituting different integrant

portions of the sun itself, are rather to be considered

as collected masses of opake matter,

interposed in the medium alone ; that from the

fugitive and evanescent nature of these spots,

it is reasonable to suppose, that they exist

below the disc of the sun, and are out of it

;

ELEMENTARY PROPERTIES

that they are totally unconnected with it, and

form no part of its body.

In venturing to draw such a conclusion,

I shall not, I trust, be accused of greater

presumption than is ascribable to those distinguished

characters, who attempt to explore,

and to ascertain, by means of telescopes,

the absolute nature of the matter of

which the sun is composed ; more especially,

when we reflect on the immense distance which

it is known to be situated from the surface

of the earth, and on the absolute necessity

which exists, of blackening the lens, through

which the rays pass, in order that the orbit of

the eye may be protected from the ardor of their

lustre.

The insufficiency in the means, has been particularly

acknowledged by Dr. Herschel himself.

The last number of the Philosophical

Transactions, contains a very interesting paper

from him, entitled,

” Astronomical Observations,

relating to the Construction of the heavenly

Bodies ;” in which he makes a marked

distinction between matter of light, or what

he denominates nebulous matter, and other

kinds of matter; and that from the nature

of its quality, and the variety of appearances,

which under different circumstances,

it assumes, it is probable, that our best inf)

F COMMON MATTER. 169

struments, will not reach so far into the profundity

of space, as to see more distant diffusions

of it ; and from the variety in the dimness,

faintness, and brilliancy of different bodies,

we may already surmise that the range of

the visibility of the nebulous matter, is confined to

very moderate limits ;” and, in order to enforce

this opinion, he repeats, at page 279,

” that

the range of the visibility of nebulous matter,

is what may be called very limited ; and

further observes, that it cannot be expected,

that such nebulosities will remain visible,

when exceedingly farther from us than the

precise nebula ; the ratio of the known decrease

of the light, will not admit of a great

range of visibility, within the narrow limits,

whereby this shining substance can affect th

eye ; and if our telescopes cannot be expected

to reach the nebulous matter, the actual quantity

of its diffusion may still farther exceed,

even the vast abundance of it already proved to

exist.”

It is impossible for me to mention the name

of HERSCHEL, without feelings of the greatest

respect. The Philosophical Transactions contain

a variety of papers from him, which

abound with a multitude of observations on

the construction of the heavenly bodies, and

of the quality of the matter of which they

are composed. In some of these papers, lie

170 ELEMENTARY PROPERTIES

seems to think that the body of the sun

is solid and massy, like any other species

of matter; but that the light, with which

the planetary spheres are illuminated, proceeds

from a luminous atmosphere, by which

the sun is surrounded ; and, that it is through

the crevices, or breaks, which sometimes take

place in the luminous matter, that the body

of the sun itself, is occasionally to be seen.

In the present essay, with a degree of candor

which does him honor, he frankly confesses,

that from greater, and more repeated, observations,

on the arrangement and magnitude of the

stars, and some other particulars, his opinions

have undergone a gradual change; and, that it is

not surprising, that many things formerly taken

for granted, should, on examination, prove to

be different, from what they were generally,

but incautiously, supposed to be. He considers,

or rather defines, nebulous matter to denote

that substance, or rather those substances,

which give light, whatsoever may be their nature,

or of whatever different powers, .they may

be possessed ; and that this nebulous matter is

not equally bright in all its parts, but that its

light is more condensed, in some places, than in

others. He uses the word condensation as the

most intelligible that he can employ. He conceives

that we can only account for the greater

brightness towards the middle of the nebula,

OF COMMON MATTER. 171

by supposing, that the nebulous matter of

which it is composed, fills an irregular kind

of solid space ; and that it is either a little

deeper in the brightest place ; or, that the nebulosity

is, perhaps, a little more compressed.

A moderate condensation, accompanied with

some little general swelling of the nebulous

matter, about the places which appear like

nuclei, will account, he supposes, for their

superior brightness ; and that several bright

nuclei, are rendered visible thereby.

The difficulty, however, of ascertaining the

probable cause of this condensation, in matter

so extremely repellent as this luminous

matter appears to be, naturally presents itself;

the subject is soon settled: instead,

says the doctor, of inquiring after the nature

of the cause of the condensation of nebulous

matter, it is sufficient for the present

purpose, to call it merely a condensing principle

; but since we are already acquainted

with the centripetal force of attraction, which

gives a globular figure to planets, keeps them

from flying out of their orbits in tangents,

and makes them revolve round one another,why

should we not look up to the universal

gravitation of matter, as the cause of every

condensation, accumulation, compression, and

concentration ofnebulous matter ? Facts are not

172 ELEMENTARY PROPERTIES

wanting, he says, to prove, that such 3,

power has been exerted, and that the globular

form of the nebulous matter, deduce4

from the round appearance of the nebulas,

may be ascribed to the action of the gavitating

principle; and, from the united testimony

of so many objects, no doubt is left about

the central seat of attraction, which in every

instance of figure is pointed out to be in the

middle ; the exertion of this supposed condensing

principle in some nebulae, it is inferred,

has been the means of producing in some of

them, a very moderate effect ; which may, perhaps,

be ascribed to the small quantity of the

preponderating, central, attractive matter ; or,

even to the shortness of its time of acting, for

in this case, millions of years are, perhaps, but

moments. In the case, however, of very narrow,

long nebulae, we may investigate the form

of the expansion of nebulous matter, by the

figure of the nebulae that have been observed,

and may be considered as consisting of their

disunion ; the most plausible way of accounting

for the apparent figure of these nebula, is

to admit that the expansion of the nebulosity

consists, indeed, of a very narrow light, and

not much depth. Granting it to be highly probable,

that the appearance of irregular round

nebulae, is owing to so many irregular gloOF

COMMON MATTER. 173

bular expansions of nebulous matter ;

it is necessary

to inquire into the cause that has

formed this matter into such masses. To ascribe

it to chance is unphilosophical ; especially as

a forming cause offers itself to our view, when

we direct our eye to the globular figure of the

planets, and satellites, of the solar system!!!

and we may confidently assign the attraction of

gravitation, as the principle which has drawn

the nebulous matter towards a centre, and collected

it in a spirical ctimpass. In the course of

the gradual condensation of the nebulous matter,

it may be expected, that a time must come,

when it cati ho longer be compressed, and the

only cause which we may suppose to put

an end to the compression, is when the

consolidated matter assumes hardness. When

we reflect on these circumstances, we may

conceive, that, perhaps, in progress of time,

these nebulae, which are already in such

a state of compression, may be still farther

condensed, so as actually to become

solid.

I have deemed it proper to give this short

abstract from Doctor Herschel’s paper, on

this interesting subject; but it must, however,

be observed, that we ought carefully

to separate the matter of fact, and of observation,

from the matter of opinion, as to the

174 ELEMENTARY PROPERTIES

causes by which the effects are produced,

which he has described.

SIR ISAAC NEWTON supposed,

” that the original

construction of matter was solid, massy,

impenetrable ; that these solid primitive particles

are incomparably harder than any porous

bodies composed of them, and that they were

so hard, as never to break in pieces. While

the particles continue entire, they may compose

bodies of one and the same nature and

texture, in all ages ; but should they wear

away, or break in pieces, the nature of all

things, depending on them, would be changed.

Water and earth composed of old worn-out

particles, and fragments of particles, would

not now be of the same texture with water and

earth composed of. entire particles in the beginning;

and, therefore, in order that nature

may be lasting, the change of corporeal things

is to be placed in the various separations, and

new associations and motions of these permanent

particles ; compound bodies being apt to

break, not in the midst of solid particles, but

when these particles are laid together, and

touch in a few parts. These particles have not

only a vis inertia accompanied with such laws

of motion as naturally result from that force,

but also are moved by certain active principles ;

a.s gravity, and that which causes the fermentaOF

COMMON MATTER. 175

tion, and the cohesion of bodies. The principles

are not to be considered as occult qualities,

supposed the result from the specific form of

things, but as grand laws of nature, by which

the things themselves are formed ; the truth appearing

to us by phenomena, though the cause

is not yet discovered.”

CHAFfER VIII.

ON THE MEANS BY WHICH COMPOUND BOWES

ARE FORMED.

IT has been my especial object, so far as I have

gone, to prove, that all the phenomena which take

place in the universe, are effects only of producing

causes ; that these effects are ends, ofwhich

there, of necessity, must have been a beginning;

that the power which was from the beginning,

is the cause to which the ultimate effect is to

be referred; (e. g.) action is the effect, of which

organisation is the cause ; organisation is the

effect of which the principle of life is the cause ;

thinking is an effect ofwhich the thinking principle

is the cause. All the children of any one

family are ends of which their parents are the

beginning; these parents are the offspring of

former parents ; the succession, therefore, may

be traced, of animals and of vegetables, to first

parents ; to first parents which did not produce

FORMATION OF COMPOUND BODIES. 177

themselves, but which were produced by some

other being : and, as every thing which is

created, must, of necessity, have had a Creator;

(because nothing which is created can be the

cause of its own creation) a time must have

been when the first vegetables were created

without seed, the first animals without intercourse.

The same observations equally apply

with respect to the existence of compound bodies,

formed from those that are simple. It

might as well be supposed, that the different

organs, of which living beings are composed,

were formed before the power which formed

them had any actual existence, as to affirm that

compound bodies existed before their elemen^

tary parts.* The qualities of those ingredients

* The nature of the power subsisting as a cause, by whose

energy various effects are produced, would, in this place,

be a proper object of inquiry ; but persuaded as I am, that

such an inquiry would not only, perhaps, be fruitless, but to

a certainty, ill received, I shall, for these reasons, avoid it.

It is, nevertheless, important to observe, that the learned

author of antient metaphysics, observes, that both nature

and artt have the same end in their operations ; and that

when the end is obtained, the thing operated upon, is in a

state of perfection, or completion ; that in the operation of both

nature and art, there is a progress, and, by consequence, a

change from one thing to another; and that this change is

motion. It is, however, very evident, that as every thing

which exists, whether by nature or art, was before it existed

possible to exist; it must, therefore, have existed

N

178 FORMATION OF COMPOUND BODIES.

(which may very properly be called elements.*

with relation to the ultimate effect) are altogether

different in their simple, from what they

are found to be in their combined, state ; insomuch,

that the definition that would point out

the nature of the one, would, in no way, apply

to the other. It is, therefore, of importance,

that we should endeavour to trace the means by

which such an infinite multitude of bodies exist,

out of elements which are, apparently, few in

number, and whose properties are certainly

different from what they were before.*

If all the matter of which the universe

is composed, had been of one simple elementary

kind ; or if that element, like the solid

in capacity, before it actually existed in energy^-In this

way he conceived that plants exist in the seed animals in the

embryo-works of art, in the idea of the artist ; and, in

short, that every thing which is made, existed in the cause by

which it was produced ; the thing, therefore, which was produced

by capacity towards energy, from what to what, is

the state between both, having a connexion between each of

them.

* If the principle of vitality had been the same throughout

the wide range of animated existence, all animals and vegetables,

instead of being different in nature, and in kind, would

have been alike in figure, and in form ; and, if attraction, and

the principle of attraction, exerted its energy on matter of the

same kind, it is probable that all the matter of the universe,

would either be all pasivity, or all power; all inertness, or all

activity.

FORMATION OF COMPOUND BODIES.

matter of earth, had been doomed to be passive

and inert, no change in nature could have

taken place ; it might have undergone different

changes, by the agency of external means but

destitute, as it naturally ‘is, of any inherent

power, of action, or of motion, it would have

continued, uniformly and invariably, the same,

during the long course of revolving ages.

The same consequences would have ensued,

if the matter of the universe had been either

fluid or gaseous only ; and more especially,

if it had been evssentially, and inherently,

solid and impenetrable.

It is far otherwise. In the system of nature,

webehold matter which possesses different powers,

and different capacities, oraptitudes, some

species that are totally active, others that are

totally passive ; some that move, others that

are moved ; some that combine, and others

that caneot resist combination. It is by virtue

of this difference which exists in the quality of

matter of different species, between the power

of some, and the weakness of others, that the

jrario’us combinations which take place throughout

the system of nature, are principally to be

referred.

When two volumes of air of the same

kindor two quantities of water, are added

together, an increase of bulk takes place in

them, in proportion to the quantity of matter

N2

180 FORMATION OF COMPOUND BODIES.

which is applied, but no other change of property

ensues. Although this accumulation has

been accomplished, by external means independently

of any internal, or inherent influence ;

it is often called by the title of the attraction of

aggregation : very different, however, it must

be confessed, are those accumulations of parts,

heaped up together by external influence, from

that bond of union by which we behold the

most minute particles of matter spontaneously,

as it were, held together. This union

is called adhesion; and the power which it

is supposed holds and binds them together,

is called attraction; adhesive attraction, or

the attraction of adhesion, is the phrase usually

employed to designate the connexion which

exists between them.

When different species of matter are brought

in contact together, and a union between

them takes place, instead of aggregation

simply, each of the bodies loses some of the

properties which it originally possessed, and

the compound which is formed, is altogether

different from the quality of the elements, or

ingredients, of which it is constituted ; arid as

some bodies are found to have a stronger tendency

to unite together, to the exclusion of

others, this preference is called affinity, or

election; and the power by which the union is

accomplished, like the bond by which the

FORMATION OP COMPOUND BODIES. 181

particles are held together, is called attraction.

The whole together is known by the name

of chemical affinity, or elective attraction.

Attraction, therefore, properly considered, may

be supposed to bear the same relation to the

union of the particles of common matter together,

that I have endeavoured to show, vitality

(or the principle of life) bears to that which is

living. While vitality is the bond, and the

power, by which the particles of organised

matter are united, and the various phenomena

of organisation produced ; attraction, on

the contrary, may be considered as the bond,

and the power, by which the individual particles

of common matter are connected; not

only in parts, but in whole it forms the source

from which the various phenomena which different

species describe, are made to flow ; and

from whence secondary or accidental qualities

arise.

The meaning which I have attached to the

term, attraction, is conformable to what is generally

understood at this time. By some it is

called,

” the power of drawing any thing ;”

” the cause by which bodies tend towards each

other, and cohere, till separated by some external

force,”

” the power, or principle, by which

all bodies mutually tend towards each other,

without regarding the cause, or kind of acti -n,

that may be the means of producing the effect.”

182 FORMATION OF COMPOUND BODIES.

SIR ISAAC NEWTON, in particular, employs the

term, attraction, in a manner the most indefinite

that can possibly be conceived ; it neither

denotes aiiy particular kind, or manner, of

action^ nor the principal cause of such action ;

but the tendency only in general, a conatus

accidendi, to whatever cause such effect may be

owing ; whether to a power inherent in the bodies

themselves ; or to the impulse ofan external

agent. In his optics, he says, Attraction may

be performed by impulse, or some other means ;

and he uses the word to signify any force, by

which bodies tend towards one another; and

again, in his first Principles, he notes,

” that

he uses the words, Attraction, Impulsion, and

Propension, to the centre, indefinitely ; and

cautions the reader not to imagine, that by

attraction, he expresses the modes of the action

in the different cases thereof, as if there were

any proper powers in the centres, which, in

reality, are only mathematical points, or as if

the centres, could attract : he considers centripetal

powers as attractions ; though, physically

speaking, it were more just to call them Impulses

; and adds, that what he calls attraction,

may possibly be effected by impulse, though

not a common, or corporeal, impulse ; or after

some manner unknown to us.”

Vague and indefinite, in its application, as

the term attraction actually is, when thus emFORMATION

OF COMPOUND BODIES. 185

ployed, it will answer every purpose, and reconcile

all contradictions; it will reconcile the

opposite, and contrary phenomena, of attraction

and repulsion the centripetal, and centrifugal

forces the motion of bodies downwards,

as well as the elevation ofthem upwards ; the

agg egation of a mass of mud, by the manual

labor of a gang of scavengers ; and the junction

of different bodies together, from chemical affinity

; and we shall be called upon, to admit

as true, the absolute solidity and impenetrability

of matter. So far, however, from solidity,

or impenetrability, being essential properties

of matter, we possess facts abundant, and

universal, to show that the primary particles of

matter, are both permeable and penetrable.

When we see water and air, and the different articles

of food which animated beings receive for

their nourishment and support, converted by

the process of assimilation, or of animation,

from a common to a living state, from insensibility

to sensibility,—from non-sense to sense,

from passivity to power, from immobility to

motion, without the penetrability of matter, no

such change could be accomplished ; if the

particles of matter were penetrable in part, and

not altogether, animated beings would form a

^ compound of life and of death,- of penetrable

matter, which had received the participation of

life ; and of matter impenetrable, which had

the power of resisting its influence.

184 FORMATION OF COMPOUND BODIES.

When we reflect on the penetrating powerof

the solar rays, and that the most solid and

compact bodies are melted and dissipated by

them* when they are concentrated, and brought

to a focus ; when we see the change total, and

complete, which takes place between different

portions of matter, by chemical combination ;

we shall be led to conclude that these effects,

can only have been accomplished, by the primary

particles of those bodies having been penetrated

; and that the new arrangements which

have taken place, altogether proceed from the

penetrability which the most minute particles of

matter have the capacity to undergo. The penetrability

of matter, may be considered as a fact,

which rests upon evidence the most notorious

and self-evident, and appears to be as demonstrable

as the attribute of extension itself. We

may be permitted to predicate the penetrability

of matter, without incurring the absurdity

which has been so much dreaded ; that in that

case, two bodies would necessarily exist in the

same place, at one and the same time.

An inquiry, therefore, into the source

whence compound bodies are formed, the nature

of the materials of which they are composed,

and in which their secondary qualities

reside, becomes absolutely necessary. I shall,

therefore, proceed to detail the various processes

classification and calorification, of refrigeration

FORMATION OF COMPOUND BODIES. 185

rand colorification. I am well aware, that in

endeavouring to connect the great chain of

effects, which are constantly passing before

our eyes with their producing causes, many

links are yet wanting ; I, nevertheless, am

of opinion, that we possess data sufficient, on

which a legitimate and natural system may be

established. If I fail in the attempt, I shall

only share the fate which my predecessors have

experienced ; and, therefore, claim for myself,

the same candor and indulgence which have

been shown to them.

CHAPTER IX.

ON THE PROCESS OF GASSIFICATION.

NATURAL philosophers have, at different times,

directed their attention to determine the agency

of that power, by which the conversion and preservation

of water into a gaseous, or aeri-form,

state, has taken place ; and its elevation upon

the surface of the earth, to high points in the firmament;

from the time that the earth was

without form and void, and darkness was

on the face of the deep, and the Spirit of

God moved on the face of the waters. DR.

HALLEY, MUSCHENBROECK, and others, supposed

that this effect was accomplished,

by a

chemical affinity, which existed between air

and water, so that the evaporation of water, at

a low temperature, depended on the mutual attraction

which existed between both ; they considered

it to be similar to the solution which

takes place of salt in water, the air dissolving

the water, as the water does the salt.”

PROCESS OF GASSIFICATION. 187

  1. HAMILTON, of Dublin, concluded, “that

evaporation is nothing else than the gradual

solution of water in air, produced and promoted

by (what he calls) attraction, assisted by heat

and motion, in the same manner as other substances

are affected.” Dr. Halley supposed

small hollow spheres of water, to be filled with a

subtile elastic fluid, which made them naturally

lighter than air ; and that a chemical union took

place between both ; air dissolving water, as

water does salt. DESAGULIERS argues, that

water is capable of being converted, by heat,

into an elastic fluid, much lighter than air ; and

ARISTOTLE ascribes exhalation to the action of

fire. LE ROY, of Montpellier, also supposed

that,

” air dissolved water, in the same manner

that water dissolved sugar ; as water, by being

heated, becomes able to dissolve a large quantity

of sugar, and of salt, and, by cooling, abandons

a part of what it had dissolved ; in like manner,

the air, as it became heated, or cooled, takes up

more or less water.” In order to ascertain the

fact, he exposed, athis window, during the night,

a white glass phial, full of air, closely tied up,

at the temperature of 79. Fahr: the mercury

fell to 68. during the night, and, on examining

the contents of the bottle, in the morning, he

found that a part of the water contained in the

air had separated, and had been deposited in

the form of little drops, which adhered to the

188 PROCESS OF GASSIFICATION.

interior sides of the vessel, which, being most

exposed, cooled the first; this accumulation

of dew became more abundant, as the thermometer

descended to 45. On exposing the bottle,

during the day, to the solar rays, the water

which had been separated during the night

from the air, became again converted into a

gaseous and vaporific form. These processes

of gassification of water, and liquefaction of

air, are always found to vary in a considerable

degree, by the influence of climates, of seasons,

of winds, and of weather, of days, and of

nights. It, nevertheless, appears that the evaporation

from ice, by the agency of the solar

rays, at a temperature considerably below 32*.

does not differ materially from that of water, at

the same temperature.

However various the means may be, by

which the process of gassification is effected,

we have evidence of the most decisive

kind, that in open space, it is greatly assisted,

if not altogether accomplished, by the

agency of the solar rays ; not only when they

issue from different bodies, into which they had

entered ; or, as they impinge on bodies whence

they are reflected ; and that it is to their power,

in particular, that the process of evaporation,

and of gassification, which is so extensively

carried from the surface of the globe, is principally

to be referred; by which, water, and

PROCESS OF GASSIFICATION. 189

other liquids, owing to the mkmte division to

which the particles, of which they are composed,

are susceptible, become acted upon, and

changed from a liquid, to a gaseous ; from an

inelastic, to an expansible, state ; leaving wet

places dry and dry places fissured and cracked;

making fogs and clouds undergo a transmutation,

from moisture to dryness, from opacity to

transparency, from inertness to motion, from

precipitation and fall, to suspension and dissipation,—

from capacity to power. It is during

this gaseous and gassified state ofthe atmosphere,

in which itmay be said to exist, in its most perfect

state of purity, and of perfection. Although it

virtually upholds, and contains, at that time, a

larger quantity of evaporated matter, which

before was opake and dense; that it is actually

most rare and transparent and with a larger

quantity of matter, which was incompressible,

inelastic, and moist; that it is most elastic,

compressible, and dry ; and most congenial to

the nourishment and support of animated beings

in general ; and to answer the other various

purposes for which it is designed, by the will of

the Almighty.

Various attempts have been made to ascertain

the quantity of water which has been evaporated,

and gassified, from a given surface.

Dr. HALLEY calculated, that the evaporation

which took place from the surface of the Me190

PROCESS OF GASSIPICATION.

diterranean Sea alone, was sufficient to yield

back all the water contained in the many

immense rivers which flow into it; and,

from the observations which were made by

Dr. WATSON, the present Bishop of Llandaff,

and which are detailed in his Chemical

Essays, for the purpose of ascertaining this

point, it appears that the quantity evaporated,

and raised from the surface of the earth,

exceeds what is generally believed : he says,

that at a time when there had been no rain

for above a month, when the grass was quite

brown and parched, the evaporation from

an acre of land, was not less than 1600 gallons,

in 24 hours ; and, in two experiments

made afterwards, when the ground had been

wetted by a thunder shower the day before, he

found, in the first experiment, the quantity of

water evaporated, was at the rate of 1973 gallons

per acre ; in the other 1905, within the

short space of 12 hours. From Mr. DALTON’S

tables it appears, that the evaporation

from a surface of water, is nearly twice as

much as from green ground ; that about eight

or nine inches of rain, are left for the supply of

springs and rivers, that this surplus of water

must be evaporated from the sea, and return to

it again by the rivers. We are likewise indebted

to COUNT RUMFORD, as well as to

MONS. SAUSSITRE, for various experiments and

PROCESS OF GASSIFICATION. 191

observations on this subject. While the experiments

of the former go to prove, that the

generation of pure air, takes place by the solar

rays acting upon water, but that it does not

take place in the dark : the observations

of the latter, in his laborious journey to the

summit of the Alps, shows the influence of

the solar rays in the process of gassification.

He observes, that in the most elevated regions,

the air is much drier than it is near the plain

surface; inasmuch, that in ascending to the

summit, his body was parched up, and the

ferrule of his carte actually dropped off. So

dry, indeed, is the air found to be at high points

of elevation, that it has been observed, that alkaline

salts, which at the bottom of amountain, will

very soon deliquesce, and run into a liquid state,

will, at the summit, remain exposed to the air

without showing the least sign of humidity.

Independently of these grand sources from

whence air and vapor are derived, there subsists

a variety of means by which they may be fictitiously

obtained ; an account of which, it is

unnecessary for me to give, as they are amply

detailed in the different works published at

different times, by eminent chemists, and are

constantly exhibited by the teachers of chemical

schools. It may, however, be stated, that

there is, perhaps, no species ofmatter whatever,

whether common, living, or dead, which does

192 PROCESS OF GASSIFICATION.

not, under certain circumstances, constitute the

agent, or the patient in the production of gassification.

We have direct evidence that every organised

system whatever, whether simple or complicated

whether vegetable or animal is in a

constant state of mutation, and decay; that all

are supplied with particular organs, by the

energy of which, the decayed particles are absorbed

and removed from the organs to which

they belonged ; and that they are excreted out

of the system, as matter dead and foreign.

Independently of the solid and liquid matter

which is thus expelled, there is also an abundant

quantity of gaseous matter, which, in animals,

is more especially expired from the

lungs and excreted from the surface ofthe skin.

The late Mr. CRUICKSHANK, and Mr. ARERNETHY,

with the utmost labor and pains, have

made a variety of experiments, for the purpose

of ascertaining the quantity of gaseous matter,

which is excreted from the skin only. Mr.

Cruickshank supposes that the cutaneous exhalation

in a man, during 24 hours, is equal to

8lbs. and 36 gr. and Mr. Abernethy, by a series

of experiments on himself, which he conducted

with the greatest patience and perspicuity,

concludes, that the quantity of liquid

matter perspired from the skin, in the same

given time, amounts to about two pounds

PROCESS OF GASSI.FICATION. 19S

and a half, and of air neatly three gallons*

On exposing the air to the usual tests, in order

to ascertain its quality, two thirds were

found to consist of carbonic acid gas, and the

remainder of nitrogen. If a mass such as this,

is produced by one individual only, during so

short a period, how immense must be the quantity,

which is generated by the whole human

race, as well as by the infinite multitude of

animals, and of vegetables, with which the

world is inhabited. The quantity of gaseous

matter, which is thus produced by animated

beings in their living state, it is probable, falls

far short, of that which is generated after

the actions of life are at an end, and after

dissolution is produced by the processes

of putrefaction and of fermentation* By allowing

the process of decomposition to take

place, in close and confined situations, a

facility is thereby afforded of collecting the

product, and of ascertaining the separate

nature of each. When the gaseous matter

which animals receive for the support of life,

during the process of inspiration, is compared

with that which is given out by the

process of expiration, the one is found to

be totally different from the other; a conclusive

proof, that it is owing to a change

which has taken place within the system,

by means of which these new properties

o

194 PROCESS Ot CLASSIFICATION.

have been acquired, during the act of incorporation

with it ; so that the system ought to be

considered the base, which gives the gas its particular

character.

Although the base from whence these gases

originate, is evidently to be referred to matter

solid or liquid, and that it is the specific

quality of the base which gives the

distinguishing character to each gas ; it is,

nevertheless, certain, that the convertibility

of the base to a gaseous state, whether it

be of a solid or liquid kind, is accomplished

by a power separate and distinct from any

inherent power resident in the base itself. We

have direct evidence, that not only animal and

yegetable matter, both solid and fluid, that

metallic oxydes, as well as the pure metal itself;

m short, that matter the most dense and solid,

of which we have any knowledge, in common

with water itself, is often converted to a gaseous

state. This change which the different

substances have undergone, which subserve to

this process, is total and complete, and no traces

whatever of the original base can be afterwards

detected.

From the concurrent evidence of our best

chemists, it may be stated, as far as chemical

analysis can be depended on that the atmosphere

consists of 77-5 parts in one hundred, by

measure, of nitrogen gas 21 parts of oxygen,

PROCESS OF GASSIFICATION. 195

1-42 of a gaseous vapor 0-&-0 of carbonic

acid gas besides a small proportion of hydrogen

gas. An analysis, such as this, is evidently

defective and imperfect ; MURRAY, therefore;

in his valuable chemical Work, very properly

rectifies this error, by defining the atmosphere

to be ” that mass of invisible and elastic fluid,

which surrounds the earth, to a great height

diminishing in density, as it recedes from the

surface, and may be regarded as a collection of

those substances, which are capable of existing,

in the aeriform state, at the medium temperature

of the globe; and which are constantly

disengaged, more or less abundantly, by the

processes going on, at the surface of the earth :

these, mixed with the substances which

they hold in solution with the water, constantly

evaporating from the surface with the

effluvia from animals and vegetables with

particles of common matter, in a state of extreme

mechanical division, and with the magnetic

and elastic fluids, light and caloric,

form a vast mixture, the composition of which

it is impossible, apparently, to determine with

accuracy.”

It must be acknowledged to be a matter of

astonishment, that the infinite variety of bodies,

both animal, vegetable, and common, which

subserve to this process, should be, ultimately,

so completely decomposed and dissolved, that

o2

PROCESS OF GASSIFICATION.

they are very seldom, if ever, reproduced, so as

to be discoverable by the nicest chemical test.

Mr. DALTON, in a place where 200 people had

been collected together, for two hours, could

only detect one part in 100 of carbonic acid

gas, and no hydrogen gas whatever, although

a quantity of both gases, must have been

given out during that period from the skin, and

lungs, of the whole assembly present.

Dr. PRIESTLEY found thatthe air of places the

most offensive and unhealthy, afforded as much

pure air, (oxygen) as that of others of an opposite

description ; the air of crouded cities of

low damp situations, or of confined manufactories,

was not less pure than the air existing in

the most open and champaign country: the nauseous

quality of the air, appearing not so much

to depend on any deficiency of oxygen air, as

on the presence of effluvia, not discoverable by

chemical means ; but which were, nevertheless,

made sensible by the sense of suffocation, and

oppression, which was felt by the persons present.

Mr. DAVY found, by analysis, that the air

from the river Senegal, in Africa, possessed

qualities precisely the same as the air of Hammersmith,

near London. BERTHOLLET ascertained,

that the air of Egypt, was like the air of

France: and Mr. CAVENDISH, likewise, found

that the air of various places yielded the same

products. DE MARTI, by experiments in

PROCESS OF GASSIFICATION. 197

Spain, obtained precisely the same materials,

and ascertained, that the atmosphere uniformly

preserved the same composition, whether with

regard to temperature to pressure, as indicated

by the barometer to winds to humidity

to the season of the year, or hour of the

day and night. GAY-LUSAC proved, by direct

experiment, that the different strata of the atmosphere,

contain the same gases, in the same

relative proportion. He filled a glass balloon,

at the elevation of 2173, and it was found to

contain, of oxygen 21-49 in 1000 parts; the

remainder was nitrogen. The atmosphere at

the surface, was analysed also at the same time,

in the eudiometer. The ABBE FONTANA, who

jnade a number of accurate experiments on the

quality of the atmosphere, in different situations,

says, that he found the air of one country,

and that of another, much more alike than

is generally believed. At Paris, he examined

the air of different places, at the same time, and

more especially of those places, in which it was

most probable to meet with infected air, be*

cause those places abounded with putrid and

impure exhalations ; but the difference did not

amount to one fiftieth of the whole. Having

taken the air from the top of a mountain,

near Paris, at the height of five hundred

feet from the plain, and compared it with the

air of Paris, taken at the same time ; after

198 PROCESS OF GASSIFICATION.

having subjected both to the same examination,

he did not find the former 1-30 better than the

latter. He also took the air from the upper gallery

of St. Paul’s cupola, which is 313 feet from

the base, and that of the stone gallery, which is

202 feet below the other, and comparing these

with the air of the adjoining street, he was not

able to detect any sensible difference between

them.

Although the correspondence which exists

between their various parts, tends to show, that

there is a considerable degree of uniformity in

the constituent materials of the atmosphere;

they, nevertheless, prove the imperfect condition

of chemical analysis also, and how inadequate

are the means which are employed, to

the attainment of the end. In the analysis

which is presented to us, neither the matter of

light, nor of fire, of color, nor of odor, are de*-

tected, or noticed,- but which are, nevertheless,

obvious and sensible to our organs of sense ;

the striking and astonishing effects which are

produced on the lungs, during the process of

respiration from the air of different situations,

prove, in a manner, the most decisive, that,

notwithstanding the supposed accuracy of

chemical analysis, an extreme degree of difference

does exist in the constituent materials of

which the atmosphere, of different places, is

composed.

HAPTER X.

jQN THE MECHANICAL PROPERTIES OF AIR IJf

JGENERAL, AND OF THE ATMOSPHERE 1^ ,

PARTICULAR.

SECTION I.

On the Power of Gaseous Matter to expand

equally in every direction.

As it was not my intention to extend the

observations I had to make, in describing the

different means by which gases are obtained,

the particular sources from whence they originate,

or the materials of which they are composed

; much less to enter into a detail of the

qualities they severally possess, or the various

changes which they undergo by chemical union

and combination, I shall proceed to explain

the physical properties which in them are inherent

and essential; and the mechanical efeffects

on other bodies, which those properties

are capable of producing.

200 PROPERTIES OF AIR

Such is the subtilty and invisibility of gaseous

bodies, that like the solar rays, their

materiality, for a long time, was disputed.

That they possess, however, the essential property

common to all matter ; that they possess

extension, or the occupation of space, is decidedly

proved, by the resistance which they oppose

to bodies moving through them, as well as

the power which they possess of excluding

other bodies, from occupying the same medium,

in which they are situated. If any hollow

vessel full of air, as for instance, a common

glass tumbler, be inverted on the surface of

any liquor, and immersed in it, the resistance

which the air opposes to the pressure of the

water, prevents the water from entering into

it beyond a certain point. If the air in the

glass be either condensed, into a smaller volume,

or entirely exhausted out of it; instead

ef the water preserving the same level which it

did before, it immediately rushes in and fills the

space which the air had occupied. Independently

of this universal attribute which air.

possesses, in common with every other species

of matter, it has properties of its own, by which

it is essentially known to be what it really is

and through which it is distinguished from

every other substance. Air is distinguished

from liquids, as well as from solids, by the

jtenuity and transparency of its parts;. and it

AND THE ATMOSPHERE. 20J

more especially obtains a generic character, by

the expansible power which it essentially contains.

That air possesses this expansible

power, is familiarly known to every tyro in

physical science. In order to prove it, I shall

have less necessity to add new facts to old

principles, than to give new principles to old

facts.

Although various external circumstances frequently

tend to direct this expansive power

into different channels ; whenever, air is situated

in space free and unconfined its expansibility^

acts equally in every direction, radiating,

as it were, from a centre, it becomes

extended to the whole circumference; so that

if a small portion of air be enclosed within a

bladder, and placed under the receiver of an

air-pump, the expansive power which the air

jn the bladder possesses, is found gradually to

dilate, in proportion as the air external to\the

bladder, in the receiver, becomes diminished.

The expansive power of air, in every direction,

is equally proved by the recoil and bursting of

a cannon, when the air in it is too closely compressed

; as it is, by the spherical appearance,

which every air bubble assumes. It is by

virtue of this particular attribute, that every

portion of air is in equilibrio with the whole ;

that it has as much the power of rising as of

falling that it possesses as much of levity, as

202 PROPERTIES OF AIR

of apparent gravity as much the power ojr

pressing bodies upwards as downwards, of

ascending into the nostrils, as descending into

the lungs ; that a small portion of air, separated

by the thinnest covering possible, from a

larger column, suffers no additional pressure ;

that the back of my hand sustains no more

pressure from the large column above, than the

palm from the small portion of air below it;

that we feel no weight that we suffer no violence

that we are exposed to no danger :

that, in fact, the equable pressure of the air,

in every direction, under the same circumstances

of external influence, is no more capable

of smashing our bodies to a cake, than it is

of bursting the parietes, or sides, of the thinnest

air-bubble that can be conceived.*1

* I might produce, without end, facts to prove this particular

attribute. The expansible power of air in every direction

is further proved, by putting a piece of lead to the

mouth of a syringe, and abstracting the air out of it ; the expansible

force of the external air, is found capable of keeping

the lead in forcible contact with the mouth of the syringe, in

whatever direction the weight may be situated. It is the case

with two hemispheres, when the air has been exhausted out

of them, &c. It is the case with a bladder placed upon an

exhausted receiver : it will burst with as much facility downwards,

sideways, and upwards, &c.

AND THE ATMOSPHERE. 203

SECTION II.

On the Equilibrium of Liquids and Solids.

THIS state of equilibrium, or of balance, is not

confined to gases only ; it more especially extends

to homogeneous bodies in general, whether

they be of a liquid, or of a solid kind.

Before the inquiry is entered into, it should

be clearly understood, that I take the natural

condition of bodies, that state of them

in which they are found to be in a common

state, as presented to us by nature, as the

principles from whence I proceed ; and that

wherever bodies are made to change their natural

state, by the operation of external causes,

that change is ever to be considered as

forced, and unnatural. The difference which

exists between a condition which is natural,

and unnatural, between the existence of any

substance in a condition which is natural, and

common to it ; and that which is artificial, and

forced, is so apparent to commonsense, that I

should not have deemed any illustration necessary

of the difference which exists between

them, had not the false philosophy of the present

day, inverted the order of things, and mistaken

the one for the other. In order to render

204 PROPERTIES OF AIR

the subject more clear, I shall give JOHNSON’S

definition of both.

” NATURAL,” produced, or effected, by nature

not artificial bestowed by nature, not

acquired not forced not far fetched: dictated

by nature following the stated course of

things.”

” UNNATURALS, contrary to the laws of nature

contrary to the common instincts forced ;

not agreeable to the real state of things ; not

representing nature.”

  1. That in the system of nature, every substance

which exists in it, is characterised by

particular attributes, which belong, and are

natural to it; and which distinguish it from

every thing else, is an incontrovertible truth*

It is these attributes that constitute the materials

on which definition is founded : thus it is,

that mens sana in corpore sano, a sound mind

in a sound body, constitutes the natural condition

of the human race ; mens insana in corpore

insano, an insane mind in a diseased body, it*

unnatural condition. It is the natural condition

for a man to stand upon his feet unnatural

for him to rest upon his head ; natural for him

to have his arms at liberty unnatural for him

to be confined in a straight waistcoat ; natural

for the different species, to have -certain deter-^

minate complexions, and forms unnatural for

AND THE ATMOSPHERE. 205

the individuals, to have the ane superseded and

obliterated, by external coloring, or the other

mutilated and defaced.

  1. It is natural for air to exist in spaces free,

and unconfined it is unnatural for it to be

confined in close vessels, and thereby prevented

from exerting the essential and natural power

it contains, of expanding, equally, in every direction.

  1. It is natural for water to subsist, in a liquid

state ; it is unnatural for it to be changed

by the operation of an external cause, either

into a gaseous, or into a solid one ; and more

especially it may be considered to subsist in an

unnatural state, when it has been acted upon,

by the living principle of animals and vegeta- ,

bles, and incorporated writh them. Under circumstances

such as these, wrater must be considered

as having lost its original properties, insomuch

that the definitions by which it was

characterised are altogether lost ; and, consequently,

that it then subsists in an unnatural

State. Whatever may be the natural and primitive

condition of water, whether it be of a

solid kind, as some individuals suppose or

that of a liquid, as is most probable -is of no

consequence with respect to the matter at issue.

Whatever change it suffers from its original

state, whether it be from a fluid into a solid, or

from a solid to a fluid one, must ever be consi206

PROPERTIES OF AIR

dered a change from better to worse. Without

dwelling upon this particular point, I shall

proceed to show, that the particles of which

liquid water is composed, in common with

those of liquids in general, with relation to each

other, subsist in a state of equilibrium, provided

those particles are of equal density.

The pressure upon the upper part is the same

as the pressure on the under one, as well as

from side to side.

If in a column of water, or any other liquid,

the particle 2 presses upwards upon the particle

1, as much as the particle 1 presses upon

the particle 2 ; and the particle 2 presses upon

the particle 3, as much as the particle 3 presses

upon the particle 2 ; and so on to an indefinite

series : then must it follow, that all the united

particles by pressing, as much as they are

pressed ; and resisting, as much as they are

resisted, subsist, with respect to each other,

in a state of perfect equilibrium. If the pressure

is equal in the particles of which a column

of water is composed, then must it follow, that

the pressure of the whole column must be

equal also. If it were otherwise, if the pressure

at the bottom, was the sum of the particles

altogether, in a regular and increasing

series, the whole would be different from the

parts. The pressure of the fluid would, in

that case, be less upwards and sideways, than

AND THE ATMOSPHERE. 207

it would be perpendicularly downwards. So

far, however, from the assertion being founded

in truth, that the pressure of water in water,

or of liquids in liquids, of equal density, is in

proportion to their perpendicular heights ; I

maintain on the contrary, that this proposition

which is so universally received as true, and

which constitutes the fundamental principle of

hydrostatic science, is altogether unfounded.

I shall not detail the experiments which are

generally used to show the equal pressure of

fluids in every direction, as they are familiarly

known to every one who has attended a single

lecture on hydrostatics ; but shall rather appeal

to the evidence of common phenomena,

as they present themselves to our observation.

We shall then find, that bodies placed at the

bottom of a column of water, suffer no more

pressure, than when they are immediately below

the upper surface of it ; and that instead of

suffering any alteration in figure, or in form,

by the increased pressure, which it is erroneously

supposed they undergo, that they continue

uniformly the same, in whatever portion

of the column they may be placed. The most

brittle bodies are often immersed at a depth the

most profound, and exposed to this supposed

pressure without cracking the most flexible

without bendingthe most expansible without

bursting. An egg, which would be broken

208 PROPERTIES OF AIR

and smashed under the pressure of two cubic

inches of lead, will remain in the sea, at the

depth of thirty fathoms, as entire and perfect

as the most solid body. The finest fibril

of the finest blade of grass, which grows

at the bottom of the ocean, is found to wave

and to float, erect and rigid, under this immense

column of water, without suffering

more pressure from it, than the grass of the

field does from the medium of air in which it is

involved. This fact is more especially illustrated,

by the perfect and entire manner in

which the leaves of corals, and of corallines,

are preserved at the greatest depths.

Immense forests of these vegetables are to be

seen, in the Indian seas; and, although the

fibres of which their foliage is composed, become

hard and firm, by exposure to the air ;

they break by the slightest touch, when they

are first taken out of the water; and yet they remain

in it, without Isesion, or violence, at the

depth of 10 and 15 fathoms from the surface.

If the assertion, which is so universally received

were true, that the pressure of water,

was in proportion to its perpendicular height

is it possible, I would ask, for any human being,

to support the pressure to which lie is often

exposed, in consequence of .being immersed

in it. The facts are so numerous and common,

AND THE ATMOSPHERE. 209

that it is almost unnecessary for me to mention

them. Having been favored with an answer

to some inquiries which I have made

upon this subject, from CAPT. HORSBURGH, a

man of the greatest veracity, and who has had

the best opportunity of accurate observation,

having navigated the Indian seas for 27 years,

I shall give an extract of his letter to me.

” I cannot give you any particulars relative

to the length of time divers can remain submerged,

from actual experience, excepting the

following instance. I was an officer of the

Gunjavar, a large ship belonging to Surat, in

1787, and being disabled, by a storm, in the

China sea, we took shelter in Galong Bay, at

the island of Hainan, which fronts the Gulf of

Tonqeen. When about to sail from thence,

our cable parted close to the anchor, in endeavouring

to weigh it ; and we got two fishermen,

who went down, and fixed a hawser to the anchor,

which lay in 11 fathoms water. These

men swam from the surface to the bottom, by

bodily strength, without any weight affixed to

them, in order to help their descent, and they

swam down alternately, to relieve each other

in the work they undertook, until it was completed

; by which we recovered the anchor.

Each of them went down about four or five

times, in the depth of 11 fathoms, and were

about two minutes under water, as near as I

p

210 PROl-EKTIES OF AIR

could judge, not having a watch upon me at

the time. I certainly did not believe it possible

for men to swim perpendicularly downwards

to the depth of 11 fathoms, and execute

a laborious task there, until I witnessed this

undertaking.

” I have heard it said, that the pearl divers,

in the Gulf of Persia, descend into depths of

30 or 35 fathoms, to procure the oysters, by

means of a heavy stone fixed to their feet by a

strap ; as soon as they reach the bottom, they

shake the stone clear of their feet, and gather

the oysters into a bag they have for that purpose;

and when they want to ascend, they

pull a cord which is connected with the boat,

or vessel, and they are immediately drawn up,

very speedily, by the persons stationed for that

purpose,”

If we, therefore, admit the estimate which is

generally made, that a cubic foot of water

weighs 64 Ib. and that a man at the bottom of

the sea, at the depth of 30 fathoms, exposes two

square feet of the surface of his body to the perpendicular

pressure of the column of water ; it

will be found, that by multiplying 180, the number

of feet, by 128, the number of pounds ; that

he must have sustained a pressure equal to

21-600 Ib. I shall not attempt to show the folly

of such a conclusion by any further detail. If

AND THE ATMOSPHERE. 211

more evidence were wanting to show that the

pressure of water is not according to its perpendicular

height, I would appeal to the hydrostatic

balance. When a substance of any

given magnitude is placed in the pan, which is

suspended in the air, it will balance the substance

in the pan under the surface of the water ;

the weight of the substance in the water, does

not increase in proportion to the depth of the

water in which it is immersed. The same

quantity of matter in the scale, which is placed

and suspended in the air, will balance the matter

in the one which is situated under the surface

of the water, as perfectly at the depth of fifty

fathoms, as it will do at the depth of one. The

pressure at the bottom, therefore, is not greater

than it is near the top. The pressure of the water

upon the under part of the scale, is exactly the

same, as the pressure upon the upper part of it ;

and by being pressed equally in every direction,

it remains suspended, and balanced, in

whatever part of the water it is situated. Notwithstanding

these most obvious truths, the

principles on which the science of hydrostatics

depends, are in direct violation of them. I

cannot expose the error of these principles

more effectually, than by quoting them as

they are expressed by authors and teachers

in general.

212 PROPERTIES OF AIR

Proposition 1 . Any part ofafluid at rest, presses

and is pressed equally in every direction.

Proposition 2. When the surface of a fluid

is level, the whole mass will be at rest.

Proposition 3. The weight of fluids is as

their quantities of matter.

It is proper for me to observe, that I have

placed these fundamental propositions in the

order which they ought scientifically to be

placed, and, for that purpose, have inverted the

mannerin which theyare generally placed,which

is as follows :

Prop. 1. The weight of fluids, is as their

quantities of matter.

Prop. 2. When the surface of a fluid is level,

the whole mass will be at rest.

Prop. 3. Any part of a fluid at rest, presses

and is pressed equally in every direction.

Although these propositions are laid down

as fundamental principles, and the truth of

them is attempted to be proved, with all the

display of mathematical demonstration, I, nevertheless,

contend, that whoever compares the

first and the third together, will be immediately

compelled to acknowledge, that they are altogether

at variance with each other. If the

pressure or weight of fluids, is in proportion to

the perpendicular height, or altitude thereof;

or to their quantities of matter ; how are these

assertions, I would ask, to be reconciled with

AND THE ATMOSPHERE. 213

the other proposition, which immediately follows

; namely, that the pressure offluids upwards,

is equal to the pressure downwards, at any given

depth ; and that when the mass is level, the

whole mass will be at rest ; and that any part

of a fluid at rest, presses and is pressed equally

in all directions ? The equable pressure of

fluids in all directions, is proved by a very simple

diagram, which being generally advanced

by the supporters of these contradictory opinions,

will, perhaps, be better understood by

them, than if it were one of my own. ” Let

  1. B. C. D. be a vessel of water, whose altitude
  2. F. is supposed to consist of a column of

10, or 10,000, aqueous particles; then it is

evident, the first, or uppermost, particle 1.

can affect the next particle 2. only by its pressure

every way, which, therefore, is as 1. and

since the particle 2. is immoveable, and action

and reaction are equal and contrary ; the said

particle 2. will resist upwards upon the particle

  1. with a force which is as 1; and it must evidently

appear, that what holds good with respect to

these, must hold good also with respect to all

the rest, in an indefinite series.”

In order, however, to reconcile contradictory

* I quote the words of others, and, therefore, am not answerable

for the folly of ascribing action and reaction to bodies,

which are stated to be immoveable.

214 PROPERTIES OF AIR

propositions by mathematical demonstration,

false conclusions are drawn in violation of the

demonstration itself; after stating it as an

evident truth, that the particle 1. can affect the

next particle 2. only by the pressure every

way; which, therefore, is as 1. and the particle

  1. will react upwards upon the particle
  2. with a force which is as 1. it is then

falsely asserted, that the particle 2. acts

on the particle 3. by pressure doivnivards with

two degrees of force, arising from its own

weight, and that of the particle above it. So

far, however, from this conclusion being justified

by the fact, facts universal falsify the

conclusion. I will maintain it as an undeniable

and universal truth, that opposing forces equally

balanced, destroy each other, wholly and totally

; that not only if a body is acted upon by

three forces, which are proportional to, and in

the direction of, the three sides of a triangle,

the body will be kept at rest ; but that it will

be more especially the case, if these forces act

equally from a centre, towards the whole of

the circumference, or vice versa. If, for example,

four powers, of whatever description they

may be, (whether they be four weights, four

levers, or four elephants,) exert equal force

in opposite and contrary directions, the effect

of the whole is absolutely lost, by the separate

power of each. If equal bulks of matter, whose

AND THE ATMOSPHERE. 215

densities^ are equal, \vhether they consist of

one cubic inch, or of the whole nucleus of the

earth, were put in opposite scales ; so long

as they were of equal magnitude, and of equal

densities, they would subsist in a state of equilibrium,

or of balance. In like manner, it is by

the pressure of water, equally in every direction,

that it produces no pressure in any ^particular

direction. It appears that the pressure produced

on bodies immersed in fluids, at different depths,

is the same; as well as the pressure of fluids,

of equal densities, upon each other ; it must

follow, then, that the fundamental proposition

in hydrostatics, which affirms, that the weight

of fluids is in proportion to their base, and perpendicular

height, is an erroneous one. It

ought, on the contrary, to be affirmed, that the

pressure of water in water, as well as of all

fluids of the same degree of density, when they

are immersed together, instead of pressing unequally

downwards, press equally sideways and

upwards.

The different experiments which are advanced

for the purpose of showing the weight

of water in water, are nothing more than so

many false facts, which only prove the density

of water with relation to the rarity of air ; or

the comparative gravity of the one, with respect

to the levity of the other. ” If a stopped phial

be suspended from an arm of a balance, in a

216 PROPERTIES OF AIR

vessel of water, and balanced by weights from

the opposite arm of the balance : upon unstopping

the phial under water, a quantity of water

will rush into it, by which the weight will be increased,

as much as the weight of the water in

the phial.” From this effect, which is thus produced,

the sinking of the bottle, when water is

substituted in it for air, it is immediately inferred,

as if demonstratively proved, that the parts of

water retain and possess their weight and gravity

in water. If the different parts are examined

which are concerned in constituting this

experimental fact the conclusion which is

drawn from it, will be found one of the most

fallacious that can be conceived; the parts

must be separated, and separately examined,

in order to show the error of the whole.

If four cubic inches of copper are immersed

in Mater, such is the density of the copper, with

relation to the rarity of the four cubic inches of

water, which the copper has displaced, that

the copper presses downwards is heavy, and

sinks to the bottom; if these four cubic inches of

copper, are beaten out into the form of a bottle,

and filled with water, the same consequences

will ensue ; although the copper bottle, filled

with water, will sink, it will not sink so rapidly

as the cubic inches of copper in a solid form

because the increased magnitude which the

copper has acquired in the change which it

AND THE ATMOSPHERE. 217

has undergone, from the cube, to the form of a

bottle, diminishes its weight in proportion to

tiie increased quantity of water which it has

displaced ; the excess of density contained by

the copper, over the water in which it is immersed,

will, nevertheless, cause the bottle to

sink. The pressure downward which is thus

produced, is not the pressure from the increased

density of the water in the bottle above that

which is external to it, both are of the same

nature: the difference altogether depends on

the difference which exists between the pressure

from the copper, overcoming the resistance

of the water. The denser body immersed

in the rarer one. If to the top of this bottle of

water, thus sinking in water, a bladder full of

air is tied to the neck of it, instead of the bottle

of water sinking as before, it will be found to

float, and to rise^on the surface the reason is

obvious ; the rarity of the air in the bladder,

together with the density of the copper, are

not equal to the density of the water alone, in.

which the bottle is placed : when a bottle of

water sinks in water, and a bottle of air swims

in it, it is not that water gravitates in water ;

but that the solid substance of which the

bottle is composed, is denser than the water

in which it is immersed ; and when a bottle of

air floats in water, it is because the air which

that bottle contains, added to the weight of the

218 PROPERTIES OF AI&

bottle, are together rarer, and consequently

lighter, than the density of the water which

they have displaced ; or, in other words, the

bottle swims by the levity of air ; it sinks by

the excess of weight in the bottle ; instead,

therefore, of proving the gravity of water in

water, it only goes to prove, that water is denser,

and consequently heavier, than air ; and

more especially than of the rarified medium

which remains after the denser parts have

been exhausted out of the bottle.

If the parts of water retained their gravity in

water, the different propositions on which hydrostatics

are founded, would be altogether

violated; instead of the different parts of a

fluid mass, being as much pressed as they are

pressing, equally in every direction, the different

parts of that fluid would press in a particular

one ; instead of the whole mass of a

fluid being at rest, when the surface of it is

level. Instead of this state of equilibrium of

equality of pressure on every direction, the

pressure of fluids would in that case be as their

quantities of matter, the pressure which they

produced would be the pressure of weight of

weight perpendicularly downwards, not sideways,

or upwards. If the weight of water increased

in proportion to its quantity, whether

of length or of breadth, or of both together, the

pressure of weight which it would occasion,

AND THE ATMOSPHERE.

would be correspondent to its perpendicular

height ; it would be similar to the pressure of

  1. block of lead, in water, or in air, at the centre

of gravity. The weight of the water would

prevent a diver from rising to the surface, as

well a& a piece of cork, or a bubble of air.

We may, therefore, conclude, that the pressure

which fluids oppose to bodies, is not the pressure

of weight ; and, consequently, that the

proposition is an erroneous one, which asserts,

” that the pressure of fluids is proportional to

the base, and the perpendicular height of that

fluid, whatever may be the form of the vessel,

or quantity of the fluid.”

It may, indeed, be stated as a corollary

from the demonstration above named, that the

pressure upon all the particles of the fluid, at

the same depth, is equal in every part, or, in

other words, the particles of fluids, at the same

depth, press each other every way, and in all

directions equally ; if this were not the case, it

is very justly observed, that if any particle of

a fluid were pressed in one part, more than it is

in another, it must give way, or yield, till the

pressure becomes every way equal ; otherwise

an incessant intestine motion of the particles

would ensue ; which is absurd, and contrary to

all experience. The particles, I maintain,

would press downwards, or sideways, as they

are found to do, when a hole is made in the

220 PROPERTIES OF AIR

bottom, or side, of a vessel full of water, or any

other fluid, immersed in a medium rarer than

the fluid which the vessel contained ; whenever

this is the case, the fluid presses more than it is

resisted, the degree of pressure depending on

the degree of difference which exists between

the density of the fluid within, and the rarity

of the fluid without : hence we find that water

which existed in equilibrio in water without

weight, in air has weight ; pressing downwards

upon the air, more than it is resisted upwards

by the air. These effects flowing from the same

principle, are observable, when fluids of different

densities are immersed together. Whenever

they do not chemically combine together,

they diffuse, and separate themselves into

different strata ; the denser falling, or sinking,

to the bottom ; and the rarer rising to the top,

in a regular and graduated manner. The

pressure, under these circumstances, is not

equal in every direction among the particles

of the whole mass ; the pressure downwards

is greater than the pressure upwards ; and a

vessel immersed in and balanced by the liquid,

would be carried down with it to the bottom of

the vessel.

The errors, on this subject, which now prevail,

appear to me to arise from subjecting to

the same laws, solids and fluids together ; bodies

whose nature and properties are altogether

AND THE ATMOSPHERE. 221

different from each other. Nothing, perhaps,

can more distinctly prove the differences which

exists in the principles on which the phenomena

of each depend, than the change which

takes place in those phenomena, either when a

liquid is converted into a fluid, or when a fluid

is converted into a solid. If a portion of

water, for example, is converted, by the process

of refrigeration, into a solid fprm, and

consolidated into ice; instead of pressing

equally in every direction, it presses in a particular

one only ; the weight of the whole mass

is concentrated into one point at the bottom,

which point is called the centre ofgravity. If

a block of lead, of any dimensions, say ten feet

square, be divided by ten lines, and immersed

in any medium rarer than itself; the pressure

of the lead, instead of extending, like the pressure

of water, equally in every direction, will

be entirely limited and confined, towards the

centre of gravity, at the bottom ; and the

weight, or pressure downwards, will then be

equal to the sum total of all the parts ; but if

the solid lead be liquified, it will, like the ice,

after it has been melted, press like other liquids,

equally every way.

The observations which I have made on

the state of equilibrium, in which the different

particles of fluids, of equal densities,

exist, with relation to each other, more especi222

PROPERTIES OF AIR

ally refer to solids in general ; to solids whose

densities are altogether equal. The particles

of which a mass of granite is composed,

with relation to each other, press as

much as they are pressed ; they resist, as

much as they are resisted ; and, therefore, virtually,

suffer no pressure; they subsist in a

state of equilibrium, or of balance. By being

incompressible in their nature, solids do not,,

because they cannot, suffer any compression.

The incompressibility of water, has been satisfactorily

proved, by the florentine experiment :

a volume of it was enclosed in a golden sphere,

and placed between two screws, and acted

upon by the most powerful agents : although

particles of the water issued through the gold,

and proved that it was porous ; it, nevertheless,

showed that water was incompressible ; and

that its bulk could not be diminished, by the

compressing force to which it was exposed.*

If liquids are in their nature incompressible,

* It ought, however, to be mentioned, that as water has,

generally, a given quantity of air diffused in it, and which

is compressible to a great degree, so as to be reducible from

a large to a smaller volume ; that whenever the experiment

has been made, and an opposite effect produced, we ought

to conclude that the small diminution of bulk which has taken

place, has, most probably, arisen from the condensation of

the air, in consequence of the compression to which it has

been exposed, and not from the condensation of the water.

AND THE ATMOSPHERE. 223

how much more is the attribute likely to belong

to those bodies which are essentially hard and

solid, whose natural tendency is to remain in a

quiescent and passive state; and which offer

resistance alone to the power by which they

are assailed.

In describing, therefore, the phenomena ofnature,

and in tracing those phenomena to their

producing causes, we must ever take things as

they subsist in their natural state. We must consider

the system ofnature, to be a system founded

in symmetry, and in order ; and which is

governed by general laws, that these laws are

all subservient to the preservation of this economy

; and that the objects dependent on this

economy are the elements, and that these elements

proceed from the most minute and active,

to the most dense and passive. The laws,

therefore, by v/hich the different elements of

which the universe is constituted are governed,

are totally different from each other ; this distinction

arises from the difference which subsists

in the quality of the matter of which they

are composed, and of the use for which they are

designed. Although it is very true, that these

elements are for the most part, at present, combined

and united ; there can be no doubt, that

they are the sources from whence the parts

proceed ; and that the laws by which the parts

are governed, are constantly exerted in order

224 PROPERTIES OF AIR

to preserve, and to restore, the symmetry and

gradation of the whole. It would seem to be

with a view to this end, that we behold the

various species of dead and of common matter,

of which the universe is constituted, obeying

certain rules of rest, or of motion, according

to the class to which it especially belongs,

and of returning to their particular elements

after they have been separated from it. Whether

it be solid, liquid, or gaseous matter

; whether it subsist by itself, or be integrated

and incorporated into other masses, it

obeys that universal law of nature, of obtaining

and preserving its proper level. It is in

obedience to these laws that solids, when they

are placed in media rarer than themselves,

gravitate and fall ; that water, elevated in

the air, above the surface of the ocean, flows

back into it; that fire, and gaseous bodies,

which are permanently elastic and expansible,

float on the surface of both. However this

tendency of preserving its proper level, may

be suspended, by the operation of external

causes, it, nevertheless, continues immutably

the same, and constitutes the vis insita, or

natural tendency which pervades every particle

of the material world. I shall, therefore,

proceed to detail the effects which are

produced, by different bodies, whenever this

state of order, and of subordination, is inverted

and destroyed.

, /CHAPTER X

ON THE GRAVITY AND LEVITY OF SOLIDS ANX>

LIQUIDS.

WHENEVER there subsists a difference in the

quantity of matter, which any body contains

within a given bulk, with relation to the quantity

of matter which it displaces the state of

equilibrium, or of balance, becomes destroyed

; instead of such a mass of matter, remaining

suspended in equilibrio, it either rises or

falls ; the weight, or pressure, downwards, is the

measure of the difference which exists between

the density of the one, and the rarity of the

other : and, on the contrary, the levity or

pressure upwards, is the test of the rarity of

the one, with respect to the density of the

other.

If a body contains as much matter as it displaces,

it remains suspended and balanced;

Q

226 GRAVITY AND LEVITY

if it contains more matter than it displaces, it

falls ; if less, it rises ; it is not to the body

alone, or to the medium alone, to which these

effects are to be ascribed, but to the mutual

relation which exists between the one and the

other. The natural measure, or test, which

exists of the different quantities of matter in

different bodies, is ascertained by the different

degrees of pressure downwards which they

produce ; so the pressure upwards of different

bodies, is the test of the comparative

degrees of rarity in the particles of matter, contained

within the same bulk, with relation to

the density of the particles of matter by which

they are surrounded. Bodies such as these,

instead of remaining suspended in equilibrio,

instead of pressing downwards, are found uniformly

to press upwards, and to rise, with a

force which is equal to the difference which

exists between the rarity of the materials of

which they are composed, and the density

of the matter in which they are immersed:

it is from this cause, that bodies are lighter

in a dense, than in a rare medium; and

heavier in a rare, than in a dense one ;

why they are lighter in quicksilver, than in

water ; in water, than in air ; lighter near the

surface of the earth, than in the most elevated

regions of the air ; and, finally, lighter in a

Receiver full of atmospheric afr, than in an

OF SOLIDS AND LIQUIDS. 227

exhausted one. Air, therefore,, confined in

close vessels, whose solid sides fraye the power

to restrain, and to subdue its expansive force,

weighed in ai> exhausted medium, will be

found more ponderable, than the same bulfe pf

air rarified ; and air rarified, more poiiderar

ble than the subtile and residuary matter, left

in the exhausted receiver ; for, however complete

the exhaustion of the air in the receiver

may appear, it, nevertheless, continues always

to he a plenum a plenum of air, dilated to the

extreme., which no instrument whatever can

exhaust.

The best air-pump that has ever been

constructed, can only exhaust the air it conr

tains, twelve hundred times its original bulk,-ran4

the Torrcellian tube, which is considered

the most perfect mode we possess of

abstracting air out of space, can never abstract

rays of light, more than of color, or of firer out

of it; or prevent them from flowing into it;

and by filling space, effectually prevent tjie

existence of a void,

I will not pretend to say, what might have

been the condition of things, at the beginning,

when the earth was without form, and void

5

or, as it probably might be better rendered,

when the earth was without form, when void,

and when darkness were on the face pf the

(Jeep. Certain, however, it is, that after Gad

Q2

226 GKAVITY AND LEVITY

said, Let there be light, and there was tight>

that not only the whole of the planetary spheres

was filled with that subtile matter, but with the

different bodies which it had acted upon, and

changed, from a solid and liquid, to a gaseous

and igneous state. Such is the essential attribute

which belongs to these different bodies,

of expanding and diffusing themselves, that the

plenitude of matter in space, is found to exist

every where, and a void no where : while extension

is the essential attribute of matter, so

space is the necessary recipient of it ; and as

matter cannot exist without space to contain

it, so space cannot subsist without matter to

fill it. Independently of supernatural means,

matter can no more be annihilated, than it can

be created ; it may be modified, and changed,

but it cannot be destroyed. However altered

in figure, and in form, the different secondary

qualities of matter may be, the substance itself

is not like the negative quantities in algebra,

that can be negatived into nothing ; and a vacuum

formed. To suppose that a perfect vacuum

can exist to suppose that a perfect

exhaustion, either subsists in nature, or can be

accomplished by artificial means, is to admit

the possibility of that which is impossible ; it

is to suppose space to be capable of existing by

itself, or in the abstract, without any necessity

for matter * to fill it. If such an incongruity ia

OF SOLIDS AND LIQUIDS. 22S

nature could be supposed capable of existing,

the bond of continuity, by which the different

particles of matter are held, and connected

together, would be separated and destroyed ;

instead of the universe in general, and this

world in particular, being intrinsically one

WHOLE ; it would, in such a case, consist of as

many distinct universes and worlds, as there are

.separated parts, or vacua ; and every vacuum

would, defacto, constitute one distinct world,

or one distinct universe. Until, therefore, such

a non-entity can be proved to have an actual

subsistence, the word vacuum, as typical and

expressive of an idea, without any prototype,

or exemplar whatever belonging to it, ought

to be blotted out of every dictionary, the

doctrine of absolute weight for ever abandoned,

and considered a positive absurdity, [t is from

principles such as these, that we are enabled

to understand the cause, why bodies in general,

(whether they be solid, liquid, or gaseous,) are

made to undergo a change from a state of equilibrium,

to a state of difference of levity, or of

gravity, according to the situation in which

they are placed.

As the doctrine of gravitation is intimately

connected with the subject I am about to discuss

; and as it is briefly, but clearly stated, by

the Rev. S. VINCE, Plumian Professor of Astronomy,

and Experimental Philosophy, at the

GRAVITY AND

^University of Cambridge, in a tract which ha

has published, with a view of accounting fofr

the causfc of gravitation, from mechanical

principles ; I shall take the liberty of making the

following extracts.

” KiEPlER supposes that the effect of attraction

Is produced by an immaterial image of the sun,

projected from the sun t6 the planet, and draw*

ing the planet towards the sun. He says,

” Effluxus igitur, quemadmodurn et lcis, imiriftteriatus

est ; non qualis odoriim cum dimi*

nutione substaniia?, non qualis ‘caloris ab ^estuante

fornace, et si quid est simile, quibus media

implentur. Relinquitur igitur, ut quemadmodum

lux, omnia terrena illustrans, species est

immateriata ignis illius, qui est in corpore solis:

ita virtus haec, planetarum corpora complexa

et vehen^, sit species immateriata ejus virtutis^

qiiae in ipso sole r^sidet, ineestihiabilis vigoris,

adeoqu actus primus omnis motus mundani.

Videri namque possit in corpore solis

latitare divinum quippiam, et comparand urn

animse nostrae, ex quo efluat species ista pla-t

netas circumagens, uti ex anima jaculantis

lapillos species motus in lapillis adhaerescitj

qua provehuntur illij etiam cum qui jaculatus

est manum ab illis reduxit.” (De Motibus

Stella Murtis.)” Etsi igitur species corporis

solariis attenuatur in longum et latum, non

minus quam lux videtur potius hoc sequen*

OF SOLIDS AND LIQUIDS. 231

tlum, effluere speciem immateriatam corporis

ipsius, cui specie! et vis prensandi, et lux, luci

vero et calor et color, quodlibet ex suo fonte

derivatum, inhaereant nee enim uspiam est

species ilia, nisi in opposite et occurrente corpore,

lucis quidem in ejus superficiei opaca ;

virtutis vero motrica in tota corpulentia : in

spatio vero interrnedio inter solera et superficiem,

non est, sed fuit.” (Epist. Astron.) It is

not here easy to annex any clear ideas to our

author’s meaning ; in what manner this immaterial

image of the sun acts upon the planet to

bring it towards the sun (vis prensandi) he has

not explained. He speaks of the cause as an

immaterial active body ; as a divine mind ; as

the mind of man ; and by its action retaining

the planets in their orbits.

” The only hypotheses which have met with

any advocates amongst philosophers, are those

of DES CAHTES, Sir I. NEWTON, and I. BERNOUILLI.

Des Cartes attempted to account

for the motions of the planets, by supposing

them to be carried round the sun in vortices.

But Sir I. Newton, besides his other arguments

against this theory, very justly observes,

that the free motioos of comets in all directions,

and their being subject to the same laws

which the planets are, destroy, at once, the

hypothesis of vortices. Sir I. Newton accounts

for gravitation in the following manner. He

$32 GRAVITY AND LEVITY

supposes that thetie is a fluid surrounding the

sunj which increases in density as it recedes

from the sun, and that u body put into this

fluid will be forced towards the sun by the difference

of the .pressures on the opposite sides.

  1. Bernoulli was dissatisfied with both these

hypotheses, and formed a system from the two,

(un juste milieu entre les deux m’a paru le plus

sur,) which he thinks will solve all the phenomena.

He supposes that there are two kinds

of vortices, one belonging to the sun, and the

other to the principal planets* He conceives

also, that there is a torrent which sets in continually

from the extremity of the vortex towards

the centre, causing thereby a tendency

of all the bodies in the vortex towards that

point ; and thus he accounts for the gravitation

of the planets to the sun. He further supposes

that there are two sorts of matter ; one, perfectly

fluid, without any elementary particles ;

without inertia ; and which gives no resistance

to bodies moving in it; the other formed of

corpuscles. These two matters are mixed together,

and form the vortex. When the vortex

first began to revolve, the particles of the second

kind of matter, receded a little from the centre,

and formed a vortex of different densities, and

thus there remained a space about the centre

of the vortex, filled with the first matter only,

and this is the matter which forms the sun. The

AND LIQUIDS. 233

matter of the sun being in an effervescent state,

small particles are thrown off, (as a steam from

boiling water,) and as these must act upon each

other, and upon the particles of the second”

kind of matter, many of them must constantly

be reflected back, and thus a current (a& before

mentioned) is continually setting in from the

extremity of the vortex towards the centre.

The particles thus thrown off, form both light

and heat. Such is the system, according to the

hypothesis of this author. But he sets out with

a supposition which can never be admitted, and

upon the truth of which his investigations depend

: that is, that the different parts of the

fluid, as it revolves about the sun, act upon

each other in proportion to their distances from

the sun, in the same manner as if they were

connected by an inflexible lever revolving about

the same centre.

” M. SAUSSURE accounts for attraction, by

supposing that all space is filled with particles

of matter, moving rapidly in all directions ; and

that the particles which fall on the opposite

sides of any two bodies, in lines parallel to the

line joining to their centres, will impel the bodies

towards each other, the sides next each

other not being so acted upon. But, in this

case, the moving force of each body would depend

on the surfaces of the bodies ; whereas it

ought to be as the quantity of matter in each

234 GRAVITY AND LEVITY

respectively. This consideration, therefore,

without entering into any further examination

of this hypothesis, is sufficient to show that it

cannot be admitted.

” The gravitation of a planet towards the sun

varies inversely* as the square of its distance

from the sun ; that is, whatever be the magnitude,

or density, of the planet, ite acceleration

towards the sun varies in that ratio. Whatever

cause, therefore, is assigned, it must satisfy

this law of variation.

” If we suppose material particles to emanate

from the sun, and ct upon the surface of the

planet, or to pervade the body and act upon

the whole of it, the tendency of such action, from

the known mechanical operations of bodies

upon each other, must be to drive the planet

from the sun. Such an emanation, therefore,

cannot be admitted as the cause of gravitation.

We will, therefore, next consider Sir I.

NEWTON’S hypothesis.

” If the sun and planets act upon each other,

it must be by some intermediate substance

which is invisible; this substance we must,

therefore, suppose to be an elastic fluid ; and

upon such a cause, Sir I. Newton attempts to

account for gravitation. In his second advertisement

to the second edition of his Optics, he

says,

” To show that I do not take gravity for

an essential property of bodies, I have added

OF SOLIDS AND LIQUIDS. 235

%rie question concerning its cause ; ch using to

propose it by way of a question, because I am

not yet satisfied with it for want of experiments.”

He, therefore, proposes (Optics, Quaery

21.) to account for the gravitation of the

planets towards the sun,

” By means of an

elastic fluid surrounding the sun (and in like

manner surrounding every other body,) suppo-^

sing this medium to increase in density, as it

passes at greater distance from the sun, causing

thereby the gravity of these greater bodies

towards each other, and of their parts towards

the bodies; every body endeavouring to go

from the denser parts of the medium towards

the rarer. For if this medium be rarer within

the sun’s body, than at its surface ; and rarer

there, than at the hundredth part of an inch

from its body ; and rarer there, than at the

orbit of Saturn ; I see no reason why the in*

crease of density should stop any where, and

not rather be continued at all distances from

the sun to Saturn, and beyond. And though

this increase of density may, at great distances,

be exceeding slow, yet if the elastic force of this

medium be exceeding great, it may suffice to

impel bodies from the denser parts of the medium

towards the rarer, with all that power

which we call gravity.”

I shall make an extract also from Mr.

Coffc’s Preface to the Translation of Sir I.

236 GRAVITY AND LEVITY

NEWTON’S Work, in order to convey to the

Superficial reader, an idea of the doctrine of

gravitation :

” that we may begin our reasoning

from what is most simple and clearest to us,

let us consider what is the nature of gravity

on earth, that we may consider it in the

heavenly bodies, situated at a vast distance.

It is now agreed, by all philosophers, that all

circumterrestrial bodies gravitate towards the

earth ! ! ! That no bodies really light are to be

found ; that what is relative levity, is not

true levity, but apparent only; and arises

from the preponderating gravity of the contiguous

bodiesv Moreover, all bodies, gravitate

towards the earth ; so does the earth again,

towards those bodies. That the action of gravity

is mutual, and equal on both bodies, is

thus proved, Let the mass of the earth be distinguished

into any two parts whatever, either

equal, or any how unequal : now if the weights

of the parts towards each other, were not mutually

equal, the lesser weight would give way

to the greater, and the two parts joined together,

would move, ad infinitum,in a right line towards

that part to which the greater weight tends :

which is altogether against experience. Therefore,

we must say, that the weights of the parts

are constituted in equilibrio; that is, that the action

ofgravity is mutual and equal on both sides.

The weights of bodies, at equal distances from

OF SOLIDS AND LIQUIDS. 237

the centre of the earth, are as the quantities of

matter in the bodies : this is collected from the

equal acceleration of all bodies, that fall from

a state of rest, by the force of their weights ;

for the forces, by which unequal bodies are

equally accelerated, must be proportional to the

quantities of matter to be moved. Now that

all bodies are in falling equally accelerated, appears

from hence, that when the resistance of

the air is taken away, as it is under an exhausted

receiver, bodies falling describe equal

spaces, in equal times.”

The equal distances which bodies describe

in equal times, whose densities are altogether

unequal, evidently prove, that weight and motion

are different from each other ; and that the

acceleration of motion, in falling bodies, depends

more on the nature of the medium in

which they are placed, than on the abstract

quantity of matter which they contain ; hence

it is, that a feather and a guinea, a rare and a

dense body, placed in an exhausted receiver,

are found to fall from equal heights, in equal

times. The weight of a body, and the motion

of a body, do not, therefore, altogether depend

on the quantity of matter in each ; we may

consequently infer, that this accelerated motion

which dense bodies acquire, in their passage

from great heights, through rare media, depends

more on the difference which exists between

238 GRAVITY AND LEVITY

them, and the rarified medium through which

they pass, than from any attracting power iu

the earth : if they fall in water, their motion is

retarded when they reach the solid matter of

the earth, it is altogether arrested ; they are

resisted by it more than they press it ; their

weight is actually, and absolutely, annihilated.

But if these effects arise from the relation which

exists between the quality of the medium, and

the matter by which they are surrounded, they

cannot arise from the attracting power of the

earth ; and, if they do not arise from the atr

tracting power of the earth, it must necessarily

follow, that gravity gravitation, or weight, is

a relative, and not a positive term. The

question then is, By what standard is this

relation to be measured? I answer, the

density which the same bulk of matter contains,

with relation to the rarity, of the

same bulk of matter which it displaces : it

is the density, or tenuity, of the medium, which

is displaced, with relation to the density, or

tenuity, of the body which displaces it, which

determines whether a body shall descend, or

ascend, or remain suspended ; and constitutes

the standard of measure. Gravitation, therefore,

properly defined, is the pressure downwards

which dense bodies produce, on such as

are rare; and levity is the pressure upwards

which rare bodies produce on such as ars

OF SOLIDS AND LIQUIDS. 239

dense ; or in other words, the rise or fall of

bodies in different moveable media, whether

solid, liquid, or gaseous, altogether depends on

the quantity of matter which those bodies severally

contain, with relation to the quantities of

matter which they displace.

It is owing to this relation which exists between

the subject which fills, and the matter

of the medium which has been dispossessed ;

that bodies of unequal bulks, have unequal

weights, in the same medium ; and, on the contrary,

that bodies of the same bulks, have un^

equal weights, in media of different densities ;

the increment of weight will be in proportion

to the decrement in the density of the medium;

and in proportion to the increment in the den*-

sity of the medium, an increment in the levity

of the body will ensue. The facts which

prove the truths of these propositions are so

universal and common, that it may, perhaps,

be considered superfluous in me to detail

them. There is not a brave sailor, who assists

at the capstern, in heaving up an anchor

from the bottom of the sea,.but knows, that the

force, or purchase, which is necessary to raise

the anchor from the surface of the sea to the

bows of the ship, is much greater than it is from

the bottom of the sea to the surface of it; the hir

crease of weight, or pressure downwards,

which the anchor has acquired in the air, above

240 GRAVITY AND LEVITY

what it contained in the water, is exactly equaF

to the difference which exists between the density

of the-water, with relation to the rarity of

the air ; the quantity of which may be ascertained

by means of a pair of scales, suspended

by a beam, with \<teights which are placed in

one of the scales, as the standard of that difference.

It is owing to the same cause, that

a cork is heavy in air, and light in water ;

and that iron is heavy in water, but light in

quicksilver ; that a bullet of lead, and a bullet

of feathers, of equal bulk, fired, at the same time,

from the mouth of the same cannon, take very

different directions. The feathers float in the

air, and are often balanced in it, but the lead,

on the contrary, after the impelling force is lost,

which it had received from the expansion

of the air, which the gunpowder contained,

gradually sinks to the surface of the earth ;*

and, as the pressure downwards is the natural

measure, or test, which exists between the different

degrees ofdensity, and of rarity, which different

bodies within the same bulk possess ; so the

* That a body loses as much of its own weight, as the

weight of the body which it displaces, is a fact which was

known as far back as the time of Archimedes : although the

story is a common one, it nevertheless, is very decisive.

Hiero, king of Syracuse, suspecting that a crown which he had

ordered a goldsmith to make fur him of pure gold, contained

OF SOLIDS AND LIOUID&. 241

pressure upwards, or levity, is the natural test

of the rarity of their composition, with relation

to the density of the medium which they have

displaced. Matter is not dense, because it is

heavy ; nor rare, because it is light ;

it is not

expansible, because it is motive; nor motive, because

it excites illumination. Those who form

these notions, have viewed the subject in an

improper manner ; they ascribe to effects the

power of cause they mistake the shadow for

the substance the secondary and accidental

property of matter, for that which is primary

and essential.

It ought, on the contrary, to be stated, that

matter is heavy, because it is dense ; that it is

a quantity of base metal, or alloy, ordered Archimedes, to

verify the fact, without mutilating the crown. After much

deliberation on the subject, it occurred to him, at the time

he was in a bath, that his body was much lighter in water,

than it was in air ; and that the cause of this difference, must

arise from the difference between the density of the medium of

water, and of air; he, therefore, ordered a crown of pure

gold to be made, which balanced the other in the air : but

upon weighing them both together in water, he found that

the first was much lighter than the second; consequently,

that that difference must have arisen from its containing matter

in it, less dense than gold. It is added, that Archimedes

was so enraptured with the discovery which he had made,

that he forgot that he was naked at the time ; and had the

indecency to run through the city in that condition, crying out,

I have found it, I have found it ! ! !

R

GRAVITY AND LEV1T\

light, because it is rare ; and that it excites

flavor and odor in sentient beings, because it is

motive. Gravity and levity, therefore are terms

which are employed to express the relative

degrees of difference which exist in the quantities

of matter, contained by different bodies,

within the same magnitudes ; and as the levity,

or the gravity the rising, or the falling, which

is in consequence produced, is entirely limited

and confined to the medium alone; I

contend, that to ascribe those effects to other

causes, and more especially to the energy of

powers, residing in bodies, which are situated

at distances, the most remote from each other

that can be conceived acting where they are

not is not only a violation of every principle

of legitimate inquiry, but of the first rules of

philosophising, adopted and recommended by

the illustrious NEWTON himself; namely, that

no more causes ofnatural things are to be admitted,

than are both true and sufficient to explain

the phenomena. In order, however, that those

phenomena should be explained, from those

principles, it becomes absolutelynecessary, that

the order of nature should be inverted, and destroyed

; instead of the matter of which this

world is constituted, proceeding, as it does,

from the most dense, to the most rare ; it ought

to proceed from the most rare, to the most

dense; the solid base ought to occupy the

OF SOLIDS AND I IQUIDS. 243

medium which is filled by the whole of the atmosphere,

and the atmosphere ought to form

the nucleus of the earth itself.

As bodies of equal bulk, lose as much of

their weight, as is equal to the bulk of the

matter which they have displaced; it is very

apparent, that bodies of unequal densities, and

of the same bulks, will not be equiponderant

in one aiid the same medium. That when the

medium is rarer than the bodies which are

placed in it, the denser bodies will weigh

more than the rarer ones ; and, on the contrary,

when they are placed in media of greater rarity

than themselves, the body of the greatest magnitude

will acquire a greater quantity of weight

than the smaller one ; thus it is that different

masses of copper, and of gold, which were balanced

in water, will be found to weigh very

unequally in air ; and if a piece of cork, and a

piece of lead, were balanced in water, it will

be found that the cork will acquire a greater

increase of weight than the lead ; and that the

weight of both will increase in proportion as

the density of the medium decreases; consequently,

that all bodies are lighter nearer the

surface of the earth, and heavier in the uppermost

part of the firmament. It is, therefore,

not only not true, that all bodies are mutually

heavy, but I contend, that instead of the gravity,

or the weight, of bodies increasing, in pro-

R2

244 GRAVITY AND LEVITY

portion as the squares of the distances from the

earth decrease ; every fact of which we have

any knowledge, falsifies the assertion, and

establishes, in a manner the most decisive, the

truth of the contrary proposition; namely, that

the gravitation, or weight of bodies, increases

in proportion as the squares of the distances

from the earth increase.

It is owing to this increase of density which

water acquires, in relation to the rarity of the air

in the upper regions, that we behold it descend

from the medium above, to the plane surface,

in the form of rain, of snow, and of hail ;

that water confined in a bucket, suspended

in the air, presses not only upon the bottom,

but upon the sides also of the bucket,

in proportion to the quantity of water in it.

The same effects take place upon the floodgates,

by which water in docks and canals

is confined, when the pressure of the water

within, is only resisted by the medium of air

without: and it is a well known fact, which I

have myself ascertained, that if a bottle full of

air, closely corked up, is sunk into the sea by

means of a heavy weight attached to it, that

the pressure of the water will overcome not

only the resistance of the air in the bottle, but

of the cork also, and force it into the bottle. I

have no doubt, that if the cork had wires passed

OF SOLIDS AND LIQUIDS. ‘ 245

through it, and the bottle were sunk to a

great depth, that the unresisting nature of the

air, with relation to the pressure of the water,

would break the bottle as perfectly as if it were

placed under a mass of granite : and there is

no proof, more obvious of the weight of water

upon air, than the condensation which air undergoes

when it is confined in a bladder, and

sunk in water.

These different facts, and a multitude of

others, which I might adduce, altogether prove

the density of water, with relation to the rarity

of the air; the pressure ofweight in the one, with

respect to the unresisting nature of the other.

A bucket full of water in water, suffers no

weight, (provided the wood is of a medium density

with the water 😉 neither does the floodgate

sustain any pressure, when the water on

the outside is at the same level as it is on the

inside. If an ocean of quicksilver were to be

placed on the outside of the flood-gate, it would

overcome the resistance of the water within it,

and the same effects would take place by the

action of the quicksilver on th gate, as took

place by the action of the water on the bottom

and sides of the bucket, while it was suspended

in the air. Cases such as these tend to showthat

the pressure which is produced by fluids, altogether

depends on the diminished resistance

246 GRAVITY AND LEVITY

which is opposed to them, by the surrounding

medium. The same effects take place when

fluids of different degrees of density, are mixed

and diffused together ; the denser fluid will

sink ; the rarer will rise. Although fluids, with

relation to each other, subsist in a state of

equilibrium, they, nevertheless, have weight,

when they are placed in media of greater rarity

than themselves ; the question is riot, whether a

bucket of water has weight in air, but whether

any solid substance, when placed at the bottom

of it, would be more pressed upon, than it

would be, if it were placed near the upper surface.

The experiment wjiich proves the question,

is decisive in itself.

If a glass tube, of an inch in diameter, is filled

with water, and a piston immersed in it, which

is suspended from the arm of a balance ; the

same weight, in the opposite scale, will balance

the piston, in whatever part of the column of

the fluid the piston is immersed ; and if the

same piston, balanced in the same way, be immersed

in any part of a volume of water of any

breadth, or depth, however great these may be,

the additional quantity of water in which the

piston is immersed, will not add one particle

to its weight ; the measure of one ounce,

which kept the piston suspended in the

tube, of oue inch bore, at the depth of one

foot, will not have that weight increased,

OF SOLIDS AND LIQUIDS. 247

if the piston were immersed in the wide ocean

itself.*

* It is owing to the relative weight which particular bodies

possess, with relation to the medium by which they are surrounded,

that advantage is taken of this property, and that

it is made instrumental to the most useful purposes. Jt is

owing to the tendency downwards, which lead, or iron,

possesses, with relation to atmospheric air, that it becomes a

power mechanical ; a power which is able to set in motion a

number of wheels, so equally and admirably adapted to the

nature of the power which causes them to move, as to produce

a regular and uniform motion on a dial, or plate, so divided

into parts, that a precise knowledge of time may be ascertained

by the different spaces over which the index is made to

move. The effects thus produced the motion which the

index describes however regulated it may be by the mechanical

construction of the machine, is altogether to be referred

to the gravity, or weight of the lead, as the prime mover of the

whole ; the weight altogether depending on the density of the

lead, with respect to the rarity of the atmospheric medium in

which it is placed. In order, therefore, that this power should

be always the same, an absolute necessity exists, that a sameness

between both should subsist. If the atmospheric medium,

instead of being the same, should occasionally vary,

the relative gravity of the weights will be, consequently, altered,

if the medium be rarer, the weight will be heavier,

and the clock will, consequently, be made to move faster ;

and if the atmosphere be more dense, the relative gravity of

the lead will be less, and the pull, or drag, on the different

wheels will, of course, be diminished ; and by being diminished,

the motion of the index will require a longer period

in performing its revolution ; it would move slower, if the

weight were immersed in water, tban in air ; and in atmospheric

air, than if suspended in an exhausted receiver.

CHAPTER Xtt.

GRAVITY AND LEVITY OF GASES,

THE observations which I have made on the

state of equilibrium, and of weight of liquids,

equally apply with respect to the equilibrium

and the weight of gases also. If any given

quantity of gas of the same quality as that of

the surrounding medium, is received in a close

vessel, it will be found to subsist in a state

of equilibrium, or of balance. When the receiver

of an air-pump is placed over the balance,

having the bottle of air suspended from

the beam on one side, and which is counterbalanced

by a weight on the opposite scale ; if

the air is exhausted, as far as it is possible, out

of the receiver, the air confined in the bottle,

will be found gradually to preponderate, and to

be heavy. The weight which the air in the

bottle has acquired, or, more properly speaking,

the weight which has been generated, is

GRAVITY AND LEVITY OF GASES. 249

exactly equal to the loss of resistance, which

the medium of air in the receiver has sustained,

in consequence of the rarefaction which it has

undergone. By artificial means such as these,

the precise degree of difference which exists,

between the density and rarity of different

gases, may be ascertained ; the number of metallic

grains employed, are standards t)f measure,

which are necessary to restore the counterpoise,

in the opposite scale, and constitute

the measure of the difference which exists between

the density of the air in the bottle, and

the rarity of the air external to it

; it gives

the relative, but not the absolute weight. If

a perfect exhaustion could be effected, we

should, in that case, have the absolute, not the

relative weight: but as this event cannot be

accomplished, we have, in every case, the relative

weight, and not the absolute one.

Various experiments have been made to ascertain

the relative weight of different gases,

not only with respect to each other, but with

respect to the utmost state of rarefaction that

can be attained : it has been found, that a

pint of atmospheric air, inclosed in a bottle, requires

the measure of about? metallic grains, to

restore the equilibrium, that hydrogen gas is

the most rare, because the lightest and carbonic

acid gas the most dense, because the

260 GRAVITY AND LEVITY OK GASES.

most heavy. The comparative degree of density,

and of rarity, between each, may be ascertained

in a different way ; it may be ascertained

by exhausting the air in the bottle, while the medium

of atmospheric air, or of any other gas, is

allowed to remain, external to it ; instead of the

rarefied air which is left in the bottle, being

balanced as before, it is found that it presses upwards,

and is lighter ; and the number of metallic

grains which are necessary to be added to

it, in order that the equilibrium may be restored

is the proper measure of the difference

which exists, between the rarefied air in the

bottle, and the dense air which has been displaced

by it.*

By means, such as these, we infer, that the

quantities of matter contained in different bodies,

are in the compound ratios of their magnitude

and densities ; and that the different mea-

* It ought, however, to be observed, that in measuring

the relative density and rarity of different bodies, by any

given standard that may be employed ; whether such standard

be solid, liquid, or gaseous, that no precise accuracy can be

expected, unless the standard which is employed is of the

same bulk, as the bulk of the matter which is to be measured

; for as every dense body loses as much of its weight,

as is equal to the bulk of matter which it displaces, the standard

of the greatest bulk, will necessarily be lighter than the

one of less bulk, and vice versa.

GRAVITY AND LEVITY OF OASES. 251

s.ures which we employ, give us the relative, but

not the absolute weight; they prove that different

gases, when they are of different densities,

press as much as they are pressed, and resist

as much as they are resisted ; that they are

neither heavy nor light, but subsist in a state

of equilibrium, or of balance; that, on the contrary,

when they are of different degrees of

density, or of rarity, they are either heavy or

light, according to the. quality of the medium in

which they are situated.*

* Sucb is the expansive force which the air exerts, when

external resistance is diminished and removed, that in making

experiments to ascertain the degree of density, which any

given quantity of it possesses, with relation to the rarity of

the medium of air by which it is surrounded or the rarity of

the one, with relation to the density of the other ; that it is

necessary to inclose it in vessels of copper, or some other

metallic substance ; as bottles made of glass, unless they are

very strong, are found generally to crack, and break. It is

more especially the case, when a large volume of air is condensed

into a smaller volume, the condensation which is

produced, must not be considered the cause of Us expansibility

; it only proves, that the expansibility of air may be

pvercome, by an external force : but it does not prove, that

pressure is able to generate expansibility in bodies, which are

not expansible. Pressure can no more create, or impart,

expansibility to air, than it does to lead, or to water ; air is

expansible ab initio, and which pressure can neither create,

nor destroy.

252 GRAVITY AND LEVITY OF GASES.

It has been in subservience to the false

proposition, so pertinaciously maintained as

true, that all bodies are mutually heavy, or

gravitate towards each other, that philosophers

have been led to confound the attributes

of those bodies, which possess a repulsive

power, with those that neither attract

nor repel ; but which merely act by the relative

degrees of density, and of rarity, which

they severally possess. As density, however

subtile it may be, is inseparable from

the existence of materiality ; all bodies under

different circumstances, may, unquestionably,

be said to possess, with relation

to each other, levity or gravity. In estimating,

however, the attributes of different bodies

with each other, that estimate ought ever

to be derived from the attributes which are

primary and essential, and not from those

which are secondary and accidental. There

are a variety of bodies which possess the

relative and accidental property of gravity, and

of levity, and which do not act by virtue of the

one, or of the other. A muscle, for example,

may be said to have weight in air, and levity

in water ; and yet it is not from its gravity

or levity, that its power is derived. A

spring may be said to have weight, and yet

it will not be pretended, that it is to its

GRAVITY AND LEVITY OF GASES.

weight, that the pressure it produces is to be

referred.

Whoever reflects on the forced and unnatural

means which it is necessary to employ, in order

to ascertain the rarity, or the density the

levity or gravity of air, will be led to conclude,

that it is not by these attributes that its power

ought ever to be meted, or measured ; for although

its expansibility is not only equal to, but

greater than its weight its weight is not equal

to, but much less than its expansible power. As

well might the muscular power of the most

gigantic arm, be legitimately estimated, when

it is paralysed by the pressure of a weight, or

when it is rendered motionless, by being rivetted

and fixed to a post, by the strongest chains,

as to ascribe to the weight of air the power it

possesses. Whenever air is confined in close

vessels, whose solid sides have the power to

restrain its expansive force ; it may then be

said to subsist, in a state of capacity, without

power ; of density, and of rarity, without expansibility

; it has then as great a tendency to

fall, as it has to rise, and is rendered altogether

subservient to the laws of the vessel in which it

is inclosed : in cases such as these, it is internal

force overcome by external resistance. When

ever external resistance is diminished, or removed

; whenever air is released from this

GRAVITY AND LEVITY OF GASES.

forced and unnatural situation, and is restored

to space free and unconfined, its power is

displayed by its activity : it neither acts by

virtue of its density, or rarity, of its gravity or

levity; it does not, like incompressible bodies,

confine itself within the same limited bounds,

nor press upwards or downwards only, from its

levity or gravity ; but expands to an indefinite

extent, from a centre to the whole circumference,

equally in every direction. The pressure

which is produced on the surrounding

medium, by the expansible power ofgases, is as

different from the pressure which is produced

by liquids, as it is from the pressure produced

by solids.

While the pressure downwards of a liquid,

placed in a medium rarer than itself, is limited

and confined to the perpendicular height only ;

the pressure produced by the weight of solid

bodies, on the contrary, congregates, as it were,

from the whole circumference, to one point, at

the bottom. The surface of a plank, an inch

in diameter, will suffer as much pressure from

a column of water, of an inch in diameter, and

of the height of twenty feet, as it will do from

a column of water of the same height, whose

diameter is as v/ide as the ocean itself. The

pressure, on the contrary, of solids, comprehends

the aggregate quantity of matter conGRAVITY

AND LEVITY OF GASES. 255

tained by the whole mass, at the centre of gravity

at the bottom, as it is called : (a centre at

the bottom!!!)*

The error of confounding the attributes of

gases with those of liquids, and of liquids with

those of solids* is not more striking than the

fashion which prevails, of confounding pressure

with resistance, power with capacity the capacity

which some bodies possess, of receiving

power through the medium of participation

from other bodies, with those which possess it

* The centre of gravity is supposed to be that point in any

body, about which all its parts are equally balanced, or kept

in equilibrio. In regular and homogeneous solids, this point

is situated at equal distances from the extremities. In irregular

bodies, however, which possess unequal degrees of density,

this point, or centre, as it is called, instead of being

situated in the middle of the line, is often more on one side

than the other ; the point of suspension altogether depending

on the equality of the matter which subsists on one side, with

respect to the other. ” 1. The pressure of fluids is in proportion

to the base, and perpendicular height of the fluid, whatever

be its form or quantity. 2. The pressure upon the

bottom of a conical vessel, is equal to the pressure upon the

bottom of a cylindrical one, of the same base and height.

  1. The pressure of a fluid upon any indefinitely small part of

the sides of the vessel which contains it, is equal to the weight

of a column of the same fluid, whose base is the part pressed,

and whose height is the distance of that part from the surface

of the fluid.” Enfuld.

256 GRAVITY AND LEVITY OF GASES.

essentially and inherently. I shall, therefore,,

proceed in the ensuing chapter, to mark the

distinction which exists between them, as being

absolutely necessary to understand the various

phenomena of nature which take place, and

more especially to show that gases do not act by

gravity or levity.

CHAPTER XIII.

EXPANSIBILITY DIFFERENT FROM IMMOBILITY,

AND MOBILITY, FROM FLEXIBILITY AND

ELASTICITY.

So totally and absolutely inert is the solid

matter of which the world is composed, that it

possesses, within itself, no power by which it

can act; neither the mass altogether, more than

the smallest particle of sand, would ever alter in

form or in position, unless it were acted upon

by agents external to itself. It is in consequence

of this natural tendency in solid matter

to remain permanently the same, offering resistance

alone to the action of those bodies by

which it may be assailed ; that it is said, to be

imbecil and inert, and to which, the term immobility

ought especially to be applied.

Whenever solid matter is acted upon, and

the resistance which it opposes is overcome ;

the changes which it is made to undergo perpetually

wear away : it gradually verges from

258 IMMOBILITY, MOBILITY, ETC.

the state of activity into which it had been

excited, into the passive and quiescent state

which is natural to it. This is the end

which invariably takes place, when one mass of

solid matter is made to act upon another; the

first loses as much of its own motion as it imparts

to the second, insomuch that the quantity

of change which is excited in the one,

entirely depends on the quantity of power communicated

from the other. This capacity to

be acted upon, this indifference to motion or

rest, is called mobility ; and the change which

the body undergoes during the transition from

one place to another, is called motion.*

The effect or change which is produced by a

moving power on a solid substance, altogether

depends on the nature of its construction. If

it cracks or breaks without yielding, it is said

to be brittle, such as glass or flint. When a

body yields without cracking, it is considered

asflexible ; this is the case with lead, with iron,

and with a variety of other bodies. This capacity

to be bent by the agency of external powers,

which particular bodies contain, without

* It is surprising Mr. Locke should have misapplied, as he

has done, the term mobility, and confounded capacity and

power together. Mobility he calls a power to be moved, instead

of a capacity or aptitude to be moved. In like manner

Sir Isaac Newton calls it a vis inertia.

FLEXIBILITY AND ELASTICITY. 259

possessing any inherent power of unbending

themselves, is therefore called flexibility ; or as

Dr. JOHNSON expresses it,

” the quality of

admitting to be bent.” The nature of this

capacity to be acted upon, is exemplified in a

common piece of iron or of wood. The particles

of matter, of which these substances are

composed, are unable to resist the power which

acts upon them. The inferior strata become

contracted, the upper lengthened, both are distorted

and bent; and finally, if the external force

be increased beyond a certain point, the bond

of continuity between* the individual particles

becomes separated, and the iron or wood snaps

or breaks. The whole effect which has been

thus produced, is evidently to be referred, not

to a power resident in these bodies, but to the

agency of the external force impressed upon

them ; it was resistance overcome by an overcoming

force.

This capacity of admitting to be bent and to

be moved by an external force, which flexible

bodies possess, extends to other bodies which

have the power of restoring themselves to their

former situation, after the external force is

removed, through the agency of which they

had been made flexible : bodies such as these,

are called elastic; of this description are steel,

whalebone, catgut, &c. &c. The distinction,

therefore, which exists between elasticity and

s 2

260 FLEXIBILITY AND ELASTICITY.

flexibility consists in this ; elasticity has the

capacity to be bent, and the power to restore

itself to its natural and original situation from

whence it had been forcibly distorted and withheld

; while flexibility, on the contrary, has the

capacity to be bent only, without the power of

unbending itself. Dr. JOHNSON, therefore, with

that wonderful power of discrimination which

on every occasion he is found to possess ; very

properly defines elasticity, to consist of a ” force

in bodies by which they endeavour to restore

themselves to the position from whence they

were displaced by an external force.” By the

substraction of which, such is the peculiarity

in the arrangement of which the elastic substance

is composed, that it has the power of

returning back to the position it was in before,

in which condition it remains.

That the return to its original situation only

of the elastic body, by the snbstraction of the

external force; is the true meaning and application

of the wrord elasticity, is further proved by

Sir ISAAC NEWTON. In his book on optics, he

says,

” when a body is compact, and bends or

yields inward to pressure, without any sliding of

its parts, it is hard and elastic, returning to its

figure with a force arising from the united attraction

of its parts.” If we, therefore, examine

the definition of the word elasticity as

{riven- by Johnson, and illustrated by Newton,

FLEXIBILITY AND ELASTICITY. 261

and as it is generally used at this day, we must

conclude that it is not only retained within the

narrow limits to which the fibres are confined,

but that it is never exerted without the intervention

of an external power impressed upon it.

Elasticity consequently consists of two properties

; of weakness and of power, of passion

and of action, of suffering to be, and of becoming

to be, offlexibility through the agency of an

external force, and secondly, ofre-action from

internal and inherent construction ; as when

Shakspeare says,

” when splitting winds make

flexible the knees of knotted oaks ;” the splitting

winds constitute the external cause, by

which the flexible knees of knotted oaks were

made to bend. Such, however, is the internal

construction of the fibres of which the oak is

composed, that they are able to return back to

their original state, as soon as the splitting

winds have ceased to rage. It is this dead

capacity of being acted upon, and of being

changed without the power of resisting action,

of being moved without the power of moving

itself, of being modelled without the power of

modellingitself, which constitutes the mobility

of LOCKE, the vis inertia of NEWTON, the flexibility

and elasticity of our modern philosophers.*

* This capacity to be acted upon is proved in a manner the

most decisive, by the commutation total and complete which

262 EXPANSIBILITY.

If I proceed from flexible and elastic bodies,

to consider the attributes of those which are

essentially expansible, although they possess, in

common with the former, the capacity to be

bent into different forms, aqd even to be compressed

from a larger to a smaller volume, by

the agency of an external force ; they nevertheless,

differ from both in points the most essential.

Instead of requiring the agency of external

pressure, in order that they may be enabled

to unbend and expand, external pressure alone

is the means by which this expansive power is

bounded and confined; instead of being like

flexible and elastic bodies, naturally passive

and artificially active, they are naturally active

and artificially inert ; they are made flexible by

pressure, but are expansible without it. The

instant external pressure is removed, this exfood

undergoes, not only with respect to quantity but to quality

also, not only with respect to configuration in general, but

to essential properties in particular, by the digestive and assisimilating

organs, with which animals and vegetables are endowed.

Having detailed at considerable length the nature

and relation which subsist between capacity and power in my

system of physiology ; to that work, I must refer the reader,

if he be desirous to understand the nature arid power of life

in converting the capacity of matter from a dead to a living

state, from a state of dispersion to a state of combination,

from a multitude of parts into one organised system, endowed

with animation and action.

EXPANSIBILITY. 263

pansive power is immediately developed from

its confinement and displayed by its activity ;

spreading and dilating to the utmost limits

which the imagination can conceive; it communicates

motion to the mobility of different bodies,

and causes pressure on all.

It is this original and essential power which

abiding in gaseous and aeriform bodies, gives

them the generic character of expansibility,

strictly so called; which identifies their nature

and distinguishes them from those belonging to

every other class. The difference between

them appears to me as great as they are important

; and will be rendered apparent, if compared

together. The motion or force which is

manifested by steel and other bodies considered

as elastic, is altogether produced by the unnatural

direction given to the particles of matter

of which they are composed ; the expansibility

of gaseous bodies proceeds from the spontaneous

and natural tendency of expanding, inherent

in them. In the one, the direction of the motion

produced, always corresponds to the particular

direction of the particles of matter of

which the elastic substance is constituted. In

the other, the dilatation which takes place, extends

equally in every direction. In the former,

the degree of motion produced is confined

within the narrowest limits ; in the latter, the

expansion is indefinite in its extent; while the

264 EXPANSIBILITY.

addition of an external force is absolutely necessary

to make a flexible body to become an

elastic one ; it is by the substraction of an external

force that gaseous bodies are enabled to

expand. Elasticity, therefore, is merely m

effecto, a power which is derived, but which

does not exist essentially ; it is an excited, not

an inherent power, whose energy immediately

ceases as soon as the compressing cause is removed,

and the particles of which the elastic

body is composed have returned to their natural

and original situation.

In matter, however, which is essentially

expansible, it is far otherwise ; instead of m

effecto, it is causa motus ; not derived from

without, but which subsists inherently within ;

not produced by external means; it is through

the resistance alone, opposed, by external

means, that this expansive power can be suspended

or suppressed. The difference may be

proved by simply placing a flexible, an elastic,

and an expansible body together, under the

same relative situations. If a small portion of

air enclosed in a large bladder is placed under

the receiver of an air-pump, with a piece of lead

or steel, the change which the air undergoes is

totally different from that of the other two.

In proportion as the air within the receiver

external to these bodies is abstracted by exhaustion

; it is found that neither the steel nor

EXPANSIBILITY. 265

lead undergo any change whatever; on the

contrary, the air within the bladder dilates and

expands to its utmost extent.

What is the extent to which air may expand,

with what velocity it may move, and what

resistance it is able to overcome, must necessarily

be very difficult to ascertain. Mr BOYLE

was of opinion, that air was capable of expanding

in the proportion from 1 to 1000 times. Sir

ISAAC NEWTON considered this property of air

to be almost unlimited and unbounded ; that it

extended, perhaps, to one million times more

than its original bulk ; that is to say, that one

cubic foot of air, at its initial state, was capable

of dilating and filling the whole space of one

million cubic feet in extent. Dr. GREGORY, in

his astronomy, mentions an opinion, which he

probably derived from Newton ; that if a cubic

foot of air were removed to the elevation of one

semi-diameter above the surface of the earth,

that it would expand and extend as far as the

orb of the planet Saturn. It is not my present

intention to examine the accuracy of these opinions,

or attempt to reconcile the difference

which exists between them. However discordant

they may appear in point of quantity, they

agree in matter of fact, and tend to establish the

wonderful power of expanding which air essentially

contains.

The late ingenious Mr. SMEATON has pub266

EXPANSIBILITY.

lished a table in vol. 51, of the Phil. Trans.:

with the intention of shewing the velocity with

which air has the power of moving, and which

is known under the appellation of wind* This

table is founded on a great number of observations

made by himself in the course of his practice

in erecting windmills.

Miles per Hour. Feet per Second of time. Names,

1

EXPANSIBILITY. 267

If we reflect for a moment on the energy

which a power such as this must exert, we

shall be at no loss to conceive the resistance

which it is capable to overcome, and the rapidity

with which bodies exposed to its force are

carried along. GARNERIN, the aeronaut, on

the 31st of June, 1802, ascended with another

gentleman from Ranelagh in a car, suspended

from an inflammable air balloon, and in fortyfive

minutes descended near the sea, four miles

frpm Colchester, a distance of sixty miles.

Allowing no time for the elevation and depressipn

of the balloon, but supposing the whole

medium of the atmosphere, and in which no wind consequently

exist. 2. Winds may be divided according to the periods or

times which they blow, and the direction in which they more.

  1. Monsoons, or periodical winds, are those which blow half

of the year from one direction, and the other half year from

the opposite one, and are generally found in the China and

Indian seas. 2. Trade winds, which resemble the monsoons,

and may be considered a species belonging to the same genus.

They are confined to the wide ocean only, at a considerable

distance from the shore, at about 28 on each side of the

equator, and are often interrupted by variations in the intensity

and direction of them, the equilibrium of the air being

often restored, and a cairn produced. At other times, light airs

taking place in different directions. 3. Variable winds> or

such as obey no regular rule, but which change in their directions

at different times, without any known or assignable

*:attse, as we behold in these latitudes.”

268 EXPANSIBILITY.

period, occupied in transferring it, in a path

nearly parallel to the earth’s surface ; its velocity

must have been at the rate of 80 miles per

hour, or 1 17 feet per second of time. If a mass

such as this could have been hurried along

with such a velocity, how much faster may we

not suppose, those vast collected masses of

vapors, known by the name of clouds, can

be made to move? How much more intensely

fast must air itself move by itself, without

impediment or obstruction? When we reflect

on the energy which such a power is

capable of exerting, we can be at no loss to

conceive how it is that the air which is generated

during the process of putrefaction and fermentation,

has the power to separate and to

decompose vegetable and animal bodies altogether

into parts, and tin ally to resolve those

parts from a dead to a common state, to eject

corks from bottles, to fissure and break into

pieces the bottles themselves in which effervescing

liquors are contained, to overcome the

bond of union by which bodies the most solid

and compact are held together, to dislocate

and devallate mountains of the greatest magnitude

into rocks, to lacerate those rocks into

fragments, to pulverise and granulate those

fragments into sand, the most subtle and minute,

we can be at no loss to understand

how it is that the small quantity of air which is

EXPANSIBILITY. 269

generated and extricated from gunpowder during

the process of detonation, is enabled to sap

and to undermine the strongest fortifications;

to project out of the mouth of a cannon a ball

to the immense distance of two or three miles ;

to explode the strongest shell from a mortar ;

to burst it into pieces, and carry death and destruction

to surrounding objects.*

In the various and multiplied discussions on

this subject, which I have had with numbers

of scientific men, and more especially with

many of my particular friends, who fill the

teacher’s chair in some of our most celebrated

schools of science in this metropolis, I have

not found an individual among the whole mass,

* Col. WILLIAMS, while serving at Quebec, filled different

iron bomb-shells of different sizes with water, and plugged

the fuEfhole close up, sometimes driving iron plugs with

a sledge hammer. When the water had been frozen, although

the plugs often weighed three pounds, they were

always forced away, by the sudden expansion of the air in the

act of freezing, like a ball impelled by gunpowder, to the

distance of 4 and 500 feet; and when the plugs were screwed

in the shell, the shell burst. Mr. Marian ascribes the expansion

that takes place at the point of freezing, not to the

extrication of air, because he says that water deprived of air,

expands equally ; he, therefore, refers the effect to the new

arrangement of the particles of the water which takes place,

in the change which they undergo from a fluid to a solid state;

it is very probable that both causes operate to produce the

effects.

270 EXPANSIBILITY.

who had any conception of expansibility subsisting

as an inherent and essential power, of

expansibility, independently of resistance. The

utmost extent of their knowledge was limited

to re-action alone ; to that sort of power which

is derived in consequence of external pressure.

It is, perhaps, still more astonishing’, that a

distinction so strong, and so well defined, has

not only been overlooked, but is, at this moment,

admitted by very few.

It appears to me very probable that the present

prejudices are merely the result of former

errors, handed down to us through the medium

of PROFESSOR GRAVESANDE and other commentators

on the laws of nature, as they have

been called, of Sir ISAAC NEWTON, who was

the original legatee. So far, however, from

considering these laws, to be laws of nature ;

from all the attention which I have given to

them, I am bound to declare that they are

mere assertions, contrary to nature ; mere abstract

terms, which require a condition of things

that in nature does not exist, but which, nevertheless,

is to be presupposed.

CHAPTER XIV.

ON THE RELATION WHICH EXISTS BETWEEN

THE EXPANSIBLE POWER OF GASEOUS BODIES,

AND THE RESISTANCE THEY ARE ABLE TO

OVERCOME.

IN the investigation of action in general, whether

original or derived, it is absolutely necessary

to ascertain the nature of the means rather

than of the end, of the cause more than of the

effect ; when the resistance is equal or greater

than the power of the body acting, the resisting

body continues passive and at rest ; when the

power is greater than the resistance, the body

moves ; the degree of motion produced, is the

proof or test which subsists, of the power in

the one, of overcoming the resistance of the

other;* so far, however, from action requiring

* Professor Gravesande ridicules the idea that action is possible

to exist without resistance : for who, says he, can conceive

the possibility of action without an obstacle ; soon after,

however, he allows resistance to be an impediment to action.

From these palpable contradictions the following corollary is

deduced, that the force and resistance are equal to one another.

272 FOWER AND RESISTANCE.

resistance, as is generally supposed, it is resisfance

alone that diminishes and ultimately destroys

action. Hence it is that bodies move

slower in a liquid than in a gaseous medium ;

faster through a liquid than through a solid one-

Notwithstanding this most obvious truth, it

is nevertheless contended by Sir Isaac Newton,

that the motion produced in different bodies,

is occasioned by a mutuality of power, subsisting

between them. It is far otherwise ; such

is the absolute inertness of the body which is

to be moved, that it is not only indebted to the

efficacy of the moving power for the velocity,

but for the line of motion also, which is produced.

The degree of motion which is produced

is the proof or test which subsists of the

power in the one, to overcome the resistance of

the other. It is by virtue of the inherent power

of acting, which animated beings in general

possess, that they are enabled to overcome resistance

and produce action, to act, without

being acted upon, to move without being moved;

that a horse is enabled to draw a cart

without the cart drawing the horse ; that the

pen with which I write is enabled to describe

the letters I am writing, the paper having the

capacity* alone of resisting the impulse which

*

By capacity I mean something which is passive only, and

by power something which is active and efficient. Capacity

POWER AND RESISTANCE, 273

it receives from my pen ; the degree of action

which is produced, does not so much arise from

magnitude, as from internal energy; from the

quantity of ponderable matter, as from activity

and skill. It is by means such as these, that

the strong in mind, but weak in body, are often

enabled to overcome the strong in body, but

weak in mind. It is in the skill which experience

is often capable of producing, that the

expert swordsman is enabled to overcome the

awkward rustic ; by which the little David was

able to slay the great Goliah,

It is this power which, in fact, constitutes

really and truly, not only vis motus, but vis

inertiae also; a power to move, as well as a

power to be quiet ; a power to act, and to resist,

as well as a power to yield, and to follow

impressions communicated and received.

It is by the expansive force of air, and of vapor,

that steam-engines are made capable of overcoming

the same degree of resistance, as the

supposed power of 10, 40, and 00 horses ; that

levers can balance, and raise, different weights ;

may be said to bear the same relation to power, as the obedience

of a servant to the will of his master as children to their

parents, as loyal subjects to the law&of the government under

which they live, and as the universe in general to the Deity

omnipotent, by whose infinite power it is governed and Coutrouled.

274 POWER AND RESISTANCE.

that whilst a ship in a calm is motionless bf

the pressure of the wind upon the sails, it is

enabled to overcome the resistance of the water,

It is owing to the resistance of the thing to

be moved, that is aseribable the impossibility

of finding out perpetual motion. The resistance

which is constantly exerted, by the friction

of the moving body, against the medium, or

sides of the matter in which it is placed, has an

unceasing and everlasting tendency, not only to

obstruct, and to weaken, but finally to destroy the

force of the moving power. Various machines,,

which are invented by the ingenuity of man, can

only diminish, they cannot annihilate resistance.

Whether the thing moved, is moved by the muscular

power of the hand by the momentum of

a rapid stream by the expansibility o’f air, or

the elasticity of fire, or any other mechanical

force whatever ; it ought to be considered as an

universal and undeniable truth, that the cause

of motion is separate and distinct, from the

thing moved, the one is the agent, the other

the patient ; the former is vis sine inertia, the

other inertia sine vi, a force without power, a

forceless force.

A vis inertiae such as this, is altogether sepa^

rate and different from the vis inertiae ascribed

by Sir ISAAC NEWTON, to matter in general,,

both dead and common ; the attribute to which

AND RESISTANCE. 275

he refers is mere capacity, not power ; it is by

calculating the different proportions which exist

between the power of the moving cause, and

the degree of resistance in the thing to be moved,

that is founded the whole science of mechanics.

So far; however, from supposing,

that in the motions which different bodies display,

there subsists between them a mutuality

of action, as Sir Isaac Newton asserts ; that

a stone draws a horse, as much as a horse

draws a cart; that a stone presses the finger,

as much as the finger presses the stone, [Quicquid

premit vel trahit alterum, tetntundem ab

eo premitur vel trahitur, si quis lapidem

digito premit, premitur et hujus digitus a

lapide* Si equus lapidem funi alligatum trahit,

retrahetur etiam et equus (ut ita dicam)

aequaliter in lapidem, &c. &c.] I contend, on

the contrary, that an assertion such as this is

erroneous in the extreme ; that it is thereby

ascribing equal powers to unequal causes ;

confounding together inanimate with animated

beings, as well as different kinds of matter,

whose nature and properties are altogether

different ; death and life, passion and action ;

things that are moved, with those that have

the power of moving; things which derive

power through the medium of participation by

an external force, with those which possess it

T 2

276 POWER AND RESISTANCE,

essentially, and in actuality ; and finally,, reaction

itself with resistance.

What analogy^ I would ask, is there between

the actions which flow from the powers,

that animated beings possess, and the passivity

of the common matter on which they

act between the reaction of a spring, and

the ponderable matter it is able to support ;

between the expansibility of air and of fire,

and the resisting bodies which they are able to

overcome and to project to the considerable

distances, which they are known to do?

So far from admitting the legitimacy of the

assumptions on which the third law of Sir

Isaac Newton’s system is founded, I contend,

that those assumptions are absolutely false;

I contend, that instead of reaction, being always

equal and contrary to action ; that it is

not equal, but that it is always less. I deny

altogether the third law, Lex, 3.

” Actioni contrariam

semper erit, et aequalem esse re-actionem

; sive corporum duorum actiones in se

mutuo, semper esse aequales et in partes contrarias

dirigi.”

It is apparent to me that, in propounding this

pretended law, Sir ISAAC NEWTON never had

in his contemplation the power which particular

bodies essentially possess, to produce

action. The very term re-action, which he

POWER AND RESISTANCE. 27?

employs, and the arrangement in which the

assertion is conveyed, show most clearly, that

he refers to the power possessed by elastic bodies

of reacting, and of returning from their

forced to their natural state. Had it been

otherwise, he would have inverted the order

and the arrangement in his terms ; instead of

saying, that reaction was equal to action, he

would have said that action was equal to reaction

; in either case, however, he would have

been incorrect He would have been incorrect,

because it is necessary in that case, to suppose

what is not, for the purpose of proving what is.

It is absolutely necessary to pre-suppose, not

only that the medium through which bodies act

upon one another, opposes no resistance whatever

to them, but that space should exist without

matter to fill it, and a vacuum be the natural

condition of the greatest part of space.

The illustrious author of this conjecture, it

appears to me, not only made it without proof,

but contrary to every principle in nature. A

condition of things such as that which has been

hypothetically supposed, I maintain is falsified

by every fact of which we are in possession ;

the plenitude of matter is the cause why a finite

power can never produce an infinite effect, and

why motion excited, perpetually diminishes,

and is ultimately lost ; it is the case with the

278 POWER AND RESISTANCE.

motion of a pendulum ; if a pendulum be set in

motion by an impelling force, the medium of

air through which it is made to move perpetually

opposes motion, without giving it : if reaction

were equal to action, the pendulum

would press the air, as much as the air presses

the pendulum, and motion perpetual might be

produced. Motion perpetual might be produced,

if we suppose that which is impossible,

that resistance could be taken away, not only

from the friction at the point of suspension, but

in the medium through which the arch is described

; if the reacting power of an elastic

body be 20, the resistance of the medium 5, the

body acted upon can only be 15. The action

produced in consequence of reaction, can,

therefore, neither be equal, nor greater; it

must, therefore, be less; if it were otherwise,

instead of the motion in a ball excited to

move, being forced ultimately to cease, it would

mofe for ever, and an infinite variety of effects

produced which these false assumptions presuppose.

On the truth or error which exists in the

assumptions, or principles, from whence different

sciences are derived, depend altogether the

truth, or error, of the conclusions which are

made. Instead of Sir I. NEWTON’S Laws of

Nature, as they have been called, being rules

POWER AND RESISTANCE. 279

of action, which all matter must obey, I contend,

that effects are constantly produced

throughout the system of nature, in violation of

them. I shall, therefore, proceed to examine

the various phenomena which different species

of matter display ; and, at the same time, show,

how much those phenomena are at variance

with the rules which those laws are intended to

describe.

CHAPTER XT.

OK THE INEQUALITY OF PRESSURE IN THE

AIR, IN CONSEQUENCE OF INEQUALITY OF

EXTERNAL RESISTANCE,

HOPING that the facts which I have advanced,

are sufficient and conclusive ; not only to prove

the expansive power of air, independently of

external influence ; and that the pressure which

it produces on surrounding bodies, is to be

referred to expansibility, not to density and

weight; I shall now proceed to detail the

effects which are produced by the air, when

there exists an inequality of resistance in the

medium by which it is surrounded.

Whenever the substraction of external resistance

takes place, from any one part, the

expansible force of the air becomes immediately

dilated, and directed to the particular

situation where the least resistance exists; a

change of pressure, consequently, takes place,

PRESSURE IN THE AIR, 281

from equality to inequality ; from radiation

equally every where, to projection unequally

somewhere. Is it not legitimate to conclude,

that it is owing to the unresisting state of the

upper regions of the firmament, that the whole

column of the atmosphere progressively decreases

in density, in consequence of increased

dilatation ; that while the expansion of the upr

per strata takes place, a, progressive diminution

of pressure from the top to the bottom,

throughout the whole atmospheric column, will

be the inevitable consequence, similar to a

small portion of air, enclosed in a large bladder,

under the exhausted receiver of an air pump ;

insomuch, that the pressure of the air, near the

surface of th^ earth, will be less in degree sideways,

and downwards, than it will be perpendicularly

upwards.

Instead of agreeing to the opinions which

now prevail, that the different strata of the

atmosphere increase in weight from top to

bottom, in a manner similar to a quantity of

fine carded wool, piled up and thrown into a

deep pit; the lower strata carrying the weight

of the upper, and being compressed by them ;

the actual condition of the atmosphere is the

very reverse of this ; the density which the

wool possesses, with relation to the rarity of the

medium in which it is situated, gives it weight ;

insomuch, that every particle of the wool

PRESSURE IN THE AIR,

to the weight of the mass, in a regular and progressive

degree, from the top, which weight becomes

concentrated at the bottom : so far, however,

from the lowerstrata of the atmosphere subsisting

in a state of condensation, like the lower

strata of the wool, from superincumbent compression,

the lower strata of the atmosphere

are in a comparative state of expansion, from a

diminution of superincumbent pressure. So

far from the lower strata of the atmosphere

supporting the upper, the upper strata are rather

pressed up by the expansive force of the

lower; instead of a progressive and gradual

sinking and condensing of the whole mass from

top to bottom, there is, on the contrary, a general

rising and lifting up of the whole mass,

from the bottom towards the top.

If the ascent of the atmosphere from the surface

of the earth, did not take place, how could

its existence, at the highest points of elevation,

be explained ? How could we account for that

immense mass, not only of water, but of different

bodies, which are there found mechanically

diffused, or chemically combined with it, in 3,

gasified state. The ascent of the air from the

surface below upwards, because less resistance

prevails, is not only a legitimate effect of the

physical properties which it possesses, but is

further confirmed by the propagation of sound;

the pulsations of the air against the auditory

AND EXTERNAL RESISTANCE. 283

iierves, are far stronger when they are directed

from the bottom to the top, than from the top to

the bottom; if it were not, therefore, for the

ascent of the atmosphere, the pulsations of the

air, would increase in force, in proportion as

they were conveyed downwards, through a

more expansible medium. Sound, from the

top to the bottom, is similar to what is experienced

by those who speak against the wind.

The ascent of the atmosphere is an opinion

which is further strengthened by the observations

made by MONS. CHARLES, in the car of

his balloon, at the time he was at the elevation

of 9,000 feet from the surface of the earth : he

observed, with great surprise, that the streamers

of his banners pointed upwards ; which, he

says, could not be the effect of the ascent, or

descent, of the balloon, as it was moving at the

time in an horizontal direction.

That a regular and progressive diminution

takes place of the atmospheric column, from

bottom to top, is proved by facts the most decisive

and satisfactory that can be devised ; it is

proved by the change which is produced on a

small quantity of atmospherical air, taken near

the surface of the earth, and carried in a bladder

to the highest point of elevation ; -the air

in the bladder is gradually found to dilate

and expand, as it does under an exhausted

receiver; insomuch, that the bladder which

284 PRESSURE IN THE AIR,

was shrivelled and fiacced, becomes round and

tense ; this effect was particularly noticed b^

Mr. BALDWIN, in one of his aerial excursions ;

he found in his ascent, that some bladders, tied

up with small portions of air in them, crackled

and expanded very considerably. The fact is

proved, by what takes place in the balloon itself;

although it appears near the surface of

the earth loose and flacced, in consequence of

not being so completely filled as it would admit;

it is seen gradually to swell and to dilate,

when it ascends to high points of elevation,

insomuch, that if a portion of the air which it

contained, were not allowed to get out of it, by

means of an aperture, constructed for that purpose

; such is the increased power of .expanding

which the air within has acquired, in consequence

of diminished resistance of the air

without, that it would burst the sides of the

balloon, and escape from its ^confinement ; as it

is found to do when it is confined in a glas

vessel, or bladder, under an exhausted receiver.

The diminution of atmospheric pressure at

high points of elevation, wras further proved by

SAUSSURK, in his ascent to the top of mount

Blanc ; not only by the great inconveniency

which he experienced in his own person, but

by the small report which a pistol fired in that

situation produced on his auditory nerves.

AND EXTERNAL RESISTANCE,

His respiration became difficult, his pulse

quick, and he was seized with symptoms of

fever; and the report of the pistol was not

heard in a greater degree, than would have

been produced by the discharge of a child’s

toy-gun near the surface of the earth. The

same effects take place upon the clapper of a

bell ; when forcibly struck against the sides,

it excites to the ear no more sound, than it is

found to do under a receiver, after a great portion

of the air it contained has been exhausted

out of it.*

* That the expansible force of the air, is the agent by

which sound is propagated and conveyed from a sonorous

body to distant objects, is decidedly proved by the cessation

of all sound in an exhausted medium. If a bell be placed

under a receiver full of air, and the clapper made to strike

against the sides of the bell ; the sound will\J)e immediately

propagated through the receiver, so as to be distinctly heard

by the bystanders ; and the sound will be found to increase

in degree, in proportion to the condensation which the air has

undergone. If a second receirer, however, be put over the

first, and the air be exhausted out of it; although the bell

within the first receiver be struck the same as before, no sound

will be heard ; we are led from thence to conclude, not only

that the pulsations of the air, are the agents by which sound

is communicated to the auditory nerves, but to understand

why it is more perfect in a dry, than in a wet day ; in a calm,

than in a storm ; in an atmosphere which is serene and clear,

than when it is foggy and wet ; finally, more perfect near the

surface of the earth, than at the top of the highest mountain.

286 PRESSURE IN THE AlK,

The facts which I have advanced are, I trus*,

amply sufficient to show that there is a pro-

The diminution of atmospheric pressure at different points

of elevation, is equally proved by the different degrees of depression

which mercury, in a torrecilian tnbe, is found to

undergo ; the experiment on this subject, which was first

suggested by DESCARTES, and put in execution by PERKIER,

although made for the express purpose of measuring the

weight of the air, proves, in a manner, sufficiently satisfactory,

the progressive diminution of expansive pressure,

which the atmosphere sustains from the bottom to the top, in

consequence of increased dilatation. Mons. Perrier, so long

ago as the year l64>6, filled two tubes, of an equal bore, with

mercury, and observed the height of it in both to be the same,

viz. 26-24 inches French, in the garden of the convent of the

Friars Minins^ situated in the lowest part of Clermont ; ort

leaving one of the barometers at the bottom of the garden,

and one of the fathers to observe it, he took the other one to

the Puy de domme, which was elevated near 500 French

fathoms above the garden, and found its height to be only

23 2-11 inches. On his return to the town, as he descended

he found, at 150 fathoms above the garden, that is 350 below

the upper station, that the mercury had risen to 25 inches ; and

on descending to the plain, he found that it rose to the same

level as the one which he had left in the garden, and which

had not varied the whole of the day. Thus a difference of

elevation of 3,000 French feet, had occasioned a depression

of 3 1-18 French inches: from which it maybe concluded,

not that 3 1-18 inches of mercury weigh as much as 3000 feet

of air ; or one-tenth of an inch of mercury, as much as

96 feet of air; but that the expansive power of air diminishes

in proportion to its dilatation ; the mercury in the*

tube sinking in the same manner as it is found to do, whew

AND EXTERNAL RESISTANCE. 287

gressive diminution in the density of the atmosphere,

from the bottom to the top ; I shall now

proceed to prove, that the increased power of

expanding which the atmosphere possesses,

from the top to the bottom, does not proceed

from the weight of the superincumbent column.

In order to make the case as clear as possible,

I shall trace back my steps, and proceed in an

inverse order to that which I have hither pursued.

  1. If a cubic foot of rarified air, at the highest

points of elevation, were received and inclosed

in a bladder of the same dimension, and carried

to the bottom ; it will be found to undergo a

change the very opposite, to that which a bladder

half full of air, taken near the surface, was

found to do, when it was carried to high points

placed in the receiver and the air which the receiver contained

exhausted out of it. Although the depression of the

mercury at different points of elevation, is not a test of the

different degrees of weight which the atmosphere possesses, it

certainly is of the progressive diminution of the expansible

power; and as it takes place in a manner which appears

(under the same state of the atmosphere) to be very regular

and progressive we may, from thence, employ the fall of the

mercury, as a measure of different degrees ofelevation. The

conclusions which were made respecting the weight, will be

the same, as if they had been made to prove the difference of

expansible power ; the only difference will be, that the conclusion

in the one case will be from a true, instead of proceeding

from false principles.

288 PRESSURE IN THE AIR,

of elevation: instead of swelling and dilating,

it is found, in the descent, to contract and collapse

into a smaller volume. There can be no

doubt that the condensation? which has thu&

taken place, has been produced by the pressure

of the external air, having overcome the

resistance of the rarified air, which the bladder

contained,

  1. In like manner, if two hollow hemispheres^

whose cavity is equal to one cubic foot, after

having had the air which they contained, exhausted

out of them, had the same quantity of

this rarified air introduced within them ; it is

very obvious that the external air would press

against the hemispheres, as it did against the

bladder, and keep them together in close COG^

tact.

  1. If this rarified air were introduced within

an exhausted receiver, to which the external

air could not obtain access, it is very clear that

the external pressure of the air must fix the receiver

to the pump-plate.

  1. That if this rarified air were introduced

into an exhausted cylinder, covered over with

a bladder ; that the bladder would be pressed

upon by the external air, and depressed into

the cylinder.

  1. That if this rarified air Were introduced

into an exhausted tube, which was placed upon

any fluid whatever, whether water or mercury,

AND EXTERNAL RESISTANCE. 289

is of no consequence ; it must be equally obvious,

that the resistance within, not being

equal to the pressure without, the fluid would

necessarily be forced up the tube, until the condensation

of the air within it was equal to the

air without it, and an equilibrium obtained; and

we may a fortiori conclude, that the degree of

elevation of the fluid within the tube would increase

in proportion to the degree of rarefaction

which could be accomplished.

  1. It is obvious, that by the abstraction of the

air, as far as was possible, out of the vessels men.

tioned, the diminished pressure within, which

was in consequence produced, would enable the

external pressure upon them from without, prc

gressively to increase ; the consequence would

be, that the glass receiver would be more firmly

fixed to the pump-plate ; that the bladder upon

the cylinder, instead of being simply depressed,

would be pressed upon with such an increased

force, that it would actually burst ; and that

the exhausted tube, whether made of glass,

iron, copper, or wood, immersed in the water,

or mercury, wotild have these fluids, by the

pressure of the external air, forced up to a

higher point of elevation than before, in the

unresisting medium which the tube contains.

It is owing to the same cause, to the dilatation

of the surrounding medium, that the va290

PRESSURE IN THE AIR,

cant space which is made by the passage of

moving bodies through the air, becomes immediately

filled ; and, finally, that the unresisting

medium which is produced in the cavity of

the thorax, in the class of mammalia, by the

elevation of the ribs, and depression of the

diaphragm ; enables the expansible power of

the air to enter the mouth and nostrils, to

fill and distend the bronchia of the lungs, and

to accomplish the process of inspiration to

accomplish it, with as much perfection in those

animals which descend from the upper regions

of the air, as it does in those that ascend up to.

them ; in an ass, whose mouth is pinned

down to the surface of the earth, as it is in a

whale, which receives the air from the upper

surface of the water.

Although we possess no means of obtaining

atmospherical air, at the highest points of elevation,

in a state of the utmost dilatation, we>

nevertheless, can imitate by art the same state

of rarefaction, near the surface of the earth, as

the air, probably, undergoes in the upper regions

of the firmament. However varied the

means may be, the object is the same ;

whether .that rarefaction be accomplished

by an exhausting syringe, according to Mr.

BOYLE’S plan, whether by filling a tube with

mercury, as TORHICKLLI did ; or by the aid of

AND EXTERNAL RESISTANCE. 291

an air-pump, as was adopted by OTTO GUERICKE.

The question itself is one of the more

or the less, and is a fit object for the inquiry of

the mechanic, in order that he may bring the

machine to its utmost state oLperfection ; its

excellence depending upon the degree of exhaustion

which it is able to produce.

When the degree of exhaustion has been

accomplished as far as it is capable ; the pressure

from without which the vessel sustains,

ma\r be considered a measure of the expansible

force of the atmosphere, with relation to the

unresisting medium within. Under these circumstances,

the Magdeburgh hemispheres of

three inches and a half diameter, require a

weight suspended from them of 140 pounds,

before the one can be separated from the

other; and Otto Guericke, in prosecuting this

experiment on a large scale, it is said, made

them to such an extent, and exhausted the

air within them so completely, that it required

the power of twenty horses, before the one

hemisphere could be separated from the other.

A thin glass bottle, exhausted of air, will

burst, in consequence of the pressure of the

atmosphere, as readily as it will do, when

full of air, arid placed under an exhausted receiver,

the only difference will be, that in

one case it will burst from without, in the

u 2

292 PRESSURE IN THE AIRy

other from within. In like manner, the receiver

of the air-pump will be immoveably

fixed to the pump-plate ; the bladder with

with which the cylinder may have been covered,

will burst, as soon as the air within is

exhausted; mercury will be forced up an exhausted

tube to the elevation of 29 or 30

inches, and water as high as 34 or 35 feet.

Although the effects which I have above

enumerated, and a multitude of others of the

same kind, evidently appear to me to be caused

by the expansible force of the air without, in

consequence of diminished resistance from a

high state of rarefaction within, and in which

the supposed weight of the atmosphere has no

concern ; I must be permitted to express my

surprise, that these phenomena, on the contrary,

are referred (by experimental philosophers

in general,) to the force of the incumbent

weight of the air, and not to its expansibility.

In order to decide the point with as much

accuracy as the subject will admit, and to

prove that it is not caused by the gravity or

weight of the atmosphere, I subjected them

to the test of experiments, in themselves so

simple, but, at the same time, so satisfactory,

that I flatter myself they will cause

the same conviction in others, as they have

AND EXTERNAL RESISTANCE. 293

done in me. I shall, therefore, proceed to show,

that the various phenomena which take place

by the mechanical power of the air, are not

referable to its weight, but to its expansible

power alone.

L It must evidently appear, that if it be the

weight of the air which, in one instance, pressed

and kept the Magdeburgh hemispheres,

when exhausted of air, by a bond so close and

firm, &s to be equal to a weight of 140 pounds,

and in the other to a power of 20 horses, before

they could be separated ; it must require

a weight equal to that force to compress them.

So far, however, from that being the case, I

placed, as many have done before rne, the

common hemispheres under a glass-receiver,

containing four cubic feet of air, the weight of

which in vacuo did not amount to one drachm,

and from which the atmospherical air, external

to the receiver, was entirely excluded; the

firmness of union by which they were held

together in the open air, did not appear to

be in the least abated, although exposed within

the receiver to a weight so extremely small.

On exhausting, however, that small quantity of

air out of the receiver, and rarifying thereby

the air without to the same state as it was

within, the one hemisphere immediately separated

from the other. If the same hemispheres

294 PRESSURE IN THE AIR,

be placed under the receiver of an air-pump,

without exhausting the air out of them, and

double the quantity of air be thrown into the

same space, it will require a double force to

separate them, so that a double atmosphere

has the same advantage over a single one, as a

single one has over an exhausted one.*

  1. In order to prove that the rupture of the

* It is to GALILEO, a celebrated mathematician of Pisa,

in Italy, that the error of measuring air by weight is to

be referred. He advanced (and maintained it to be an undeniable

truth) both in philosophy and mechanics, that no heavy

body ascended, without another heavy body descending as a

counterpoise to it ; he was the first who supported and suggested

the doctrine, that preternatural ascent of fluids arose from a

regular and natural cause in the weight and pressure of the air.

It was this hint which led TORRICELLIUS, of Florence, in

1643, to perform a variety of experiments, with a view of

ascertaining the weight of the air, and to form the first rough

model of a barometer ; he constructed a tube 60feet hi length,

which he afterwards reduced to 40, by suspending it in water,

and by means of a sucker attached to the upper part of it, on

exhausting the air out of it he found that the water followed

the sucker, and rose to 32 33 feet, but no art whatever could

elevate it beyond 38 or 40 feet. Such was the unweildiness

of the instrument, that it required the sails of a windmill to

invert the tube : he therefore availed himself of the mean and

relative weight which mercury bore to water, so that by substituting

mercury for water, he was enabled to reduce the

length of the instrument from 40 feet to 33 inches.

AND EXTERNAL RESISTANCE, 295

bladder, with which an exhausted receiver is

covered, is not caused by weight or the per*

pendicular pressure downwards of gravitating

or ponderable air, is proved by the bladder

bursting with as much facility if it be exposed

to the lateral, as to the perpendicular pressure,

upwards as downwards. To decide the point,

however with the utmost accuracy, I placed a

small cylinder, having

a bladder closely

tied over its top,

upon an exhausting

pump ; and over the

cylinder thus capped,

a receiver ; so

that there were between

the receiver

and the cylinder,

six cubic inches of

atmospherical air,

weighing about 10 grains, from which the external

air was entirely excluded. On exhausting

the air out of the cylinder, the bladder with

which it was covered, burst with as much facility

by the force of those 10 grains of air, as

it does when exposed to the influence of the

whole weight which it is supposed the column

of atmosphere exerts on the surface. If weight

.therefore, be the cause, of which the bursting296

PRESSURE IN THE Allt,

of the bladder was the effect, it must unavoidably

follow, that this effect was accomplished

from the weight of the air between the cylinder

and the receiver, and which before was ascertained

to amount to 10 grains only. On placing,

howeVer, a weight over the bladder, not of

10 grains, but of 18 pounds, it was found capable

of supporting it, without suffering any lesion

whatever.

As the weight placed upon the bladder covering

a full receiver, may not be considered

to be under the same circumstances as it is,

when the air is exhausted out of it; and with a

view of ascertaining what degree of weight is

absolutely necessary to burst the bladder, abstractedly

from the air ; I stretched a bladder

upon an open frame, and placed upon it a

weight of 18 pounds, and over it a receiver;

on exhausting the air out of the receiver, the

bladder was enabled to support the weight,

without being ruptured, equally well as if it

had been exposed to the open air. It is, therefore,

legitimate to conclude, that although the

effect produced, the bursting of a bladder over

an exhausted receiver, is caused by the pressure

of the air, yet, that it is not caused by the

pressure of weight, but is to be referred to the

pressure of expansibility alone, which air has

been proved to possess ; which expansibility is

AND EXTERNAL RESISTANCE. 297

Universally exerted, whenever the equilibrium

is destroyed, and where the least resistance

prevails.

I have deemed it proper to dwell at some

length on this part of the subject,, in order

that I might put it on its proper footing, and

explain away the improper notions to which it

has given rise; notions which have led to the

most erroneous conclusions to the erroneous

suppositions that it is the weight, and not the

expansibility of the air or atmosphere, which

causes the elevation of the mercury in the Torricellian

vacuum as it is called, as well as that

it is not the expansibility, but the weight of the

air, that causes the depression and rupture of

the bladder over an exhausted receiver; when

in fact the weight of the air is no more concerned

in elevating the one, than in cracking the

other.

In order to prove the fact, I placed and immersed

the bottom of a Torricellian tube in a

basin of quicksilver, and placed a receiver

over it ; in the top of the receiver, a screw

was inserted, with a stop-cock attached to

a bladder, which had been previously filled

with common atmospherical air, as nearly

as possible of the same dimensions with those

298 PRESSURE IN THE AIU,

of the receiver

itself; the

volume of air

amounting to 2

feet, the weight

ofwhich might

amount to 30

grains. The

whole apparatus,

therefore^

consisted <H

a Torricellia

tube filled withV <^

quicksilver in v

the usual way,

placed under the

receiver. On

exhausting the

air out of the

receiver, the

mercury in the

tube immediately

sunk to

the. same lev el

as the mercury in the basin. By turning the

stop-cocks, the air which the bladder contained

immediately passed into the receiver; the effects

of which were rendered evident, by the

alteration which the mercury in the basin underwent

; the mercury which before was at the

AND EXTERNAL RESISTANCE. 299

bottom of the tube, at the same level with that

in the basin, immediately ascended in the exhausted

and unresisting medium which the

Torricellian tube contained, to the elevation

of 29|- inches, being of the same level as one

exposed to the open air. It must, therefore,

follow, that if the elevation of the mercury

under the receiver was the consequence of

weight, it must have been accomplished by

the weight of the air which had passed from

the bladder into the receiver, and which before

I had ascertained to have amounted to 30

grains only. With a view of seeing whether the

same weight of ponderable matter, lead for instance,

would have the power ofelevating themercury

from the basin into the tube, I placed 100

grains of lead on the mercury in the basin; on

exhausting the air out of the receiver, so far

from that weight of lead being adequate to preserve

the mercury in the tube to the same elevation,

as the pressure produced by one tenth

part of the same weight of air ; I found, on

exhausting’ the air out of the receiver, that the

mercury in the tube sunk to the same level as

the mercury in the basin. I endeavoured to

ascertain what quantity of weight was adequate

to raise the mercury in the tube exposed to the

open air above the standard it was then of 29J

inches. I, therefore, placed a piece of pasteboard

over the mercurv in the basin, as well

300 PRESSURE IN THE AIR,

adjusted as was possible, having an aperture

for the passage of the tube, and found that it

required the additional weight of 10 ounces and

6 drachms to raise the mercury in the tube one

quarter of an inch, that is to say, from 29^

inches, to 29f. With a view of varying these

experiments, and to obtain additional evidence,

that it is the pressure of expansibility

and not the pressure of weight which air exerts

when the equilibrium is destroyed, as is the case

in exhausted media in general, and in the Torricellian

vacuum, as it is improperly called, in

particular; I took equal and separate portions

of different gases, whose relative weights are

Jknown to be different from each other, I inclosed

each gas separately in each bladder, and

screwed the bladder as before to the receiver in

which the Torricellian tube was placed ; one

bladder contained hydrogen gas, 2nd, oxygen

gas, 3rd, atmospherical air, and 4th, carbonic

acid gas ; the tubes were of the same lengths,

but the’ bores were different ; varying in size,

from % of an inch, to 1 inch in diameter.

On exhausting the air which the receiver contained,

the mercury in all sunk in the same

time from 29^- inches to the same level as the

mercury in the basin : on admitting each gas

to each tube, it was uniformly found, that neither

the difference in the weight of the gas, nor

the difference of the bore in the tube, produced

AND EXTERNAL RESISTANCE. 301

any difference whatever in the elevation of the

mercury. It was found that pure hydrogen

gas, which is considered to be 13 times lighter

than atmospherical air, was able to raise the

mercury from its level in the basin to 29^

inches, equally and as rapidly as either the oxygen

or atmospherical air, and more especially as

the carbonic acid gas, which is the most ponderable

of the whole; and that the size of the tube,

and consequently the quantity of mercury in it

to be raised made no difference whatever ; the

mercury in the smallest tube did not rise faster

or ascend higher than the mercury in the largest.

Although I had not the means of pushing

the experiment to a greater length, than that of

raising 30lb weight of mercury with four pints

of hydrogen gas, which do not weigh 2 grains,

I have every reason to believe that these 2 grains

weight of hydrogen gas would be capable of

elevating, and of preserving in a state of suspension

to the height of 29 inches in an exhausted

tube, a quantity of mercury of the greatest

magnitude. To those, indeed, who are not

disposed to ascribe the elevation of the mercury

in an exhausted tube, or water in exhausted

pumps, to the expansible power of the

external air, I would recommend them to as^

certain the fact by the easiest of possible means.

It may be proved by simply placing two instru302

PRESSURE IN THE AIR,

ments, improperly called barometers* under

different states of atmospherical influence ; the

one under a glass receiver from which the external

air is entirely excluded, containing* any

quantity of air, say 2 cubic feet, weighing 25

or 30 grains ; the other in open space, exposed

to the influence of the whole atmospherical

column; it must evidently follow, that if the

elevation of the mercury in the tube be caused

by weight, by the pressure of weight of the atmosphere

; the mercury in the tube of each

instrument ought to undergo unequal degrees

of elevation ; so far, however, from the elevation

being unequal, the mercury will be

found to preserve the same parallel in both.

The preservation of the mercury to the same

parallel in two instruments placed in situations

so totally different from each other, either proves

*

Properly speaking, a barometer is a measurer of weight

only, and consists of a pair of scales with a weight in one

balance, with a view of measuring the pressure of weight

produced by the matter contained in the other ; and the barometer,

as now constructed, may be employed for the same

purpose; it may be employed also as an excellent measure,

for ascertaining the relative effect produced by weight, and

the pressure produced by expansibility, as well as between

the relative degrees of expansible pressure, which are exerted

by different gaseous fluids. In every case, the degree of elevation

of the mercury in the tube will be the sum of the

pressure produced.

AND EXTERNAL RESISTANCE. 303

the absurdity, that equal effects can be produced

by unequal causes, or that the weight of 25

or 30 grains can accomplish as much as the

whole incumbent weight which the atmosphere

is falsely supposed to possess : if the receiver,

with which the first instrument was covered,

be removed, and exposed to that supposed

weight, the mercury within it continues unaltered.

The conclusion, therefore, presses upon

the mind with force irresistible, that the elevation

of the mercury in the Torricellian tube,

and the various degrees of elevation and depression

which it undergoes, are not caused

, by the weight or gravity of the air ; and

that the weather-glass now in general use,

called barometer, from 0f nfyov, a meter or

measurer of weight, is called by a term

which is irrelevant and improper, but that

the term ana-plometer, from the compound

word avaKKou ftfyov, a meter or measurer of expansibility,

ought to be substituted for it. So far,

therefore, from the barometer measuring the

degree of pressure which the atmosphere exerts

by its weight, it is by its expansibility alone

that the atmosphere acts, pressing with the

greatest force when it is least ponderable, and

when it is most ponderable exerting the least

pressure; that is to say, that it is most expansible

when least ponderable, and least ponderable

when most expansible.

During the various discussions which I have

304 PRESSURE IN THE AIR,.

had upon this subject with men of science, I

have been much amused with the various arguments

they have employed, and with the different

false facts which they have advanced, in

order to invalidate the force of these experiments.

Tt was said by one, that instead of

employing a bladder of the same size as the

receiver, a glass globe ought to have been

used ; and in that case, on letting in the air

from the globe into the receiver, the mercury,,

instead of rising to 29 inches, would only have

risen to half that height. Nothing can be morecertain,

and the reason is most obvious ; instead

of the air which was contained in the

globe being altogether transmitted from it into

the receiver only, as it is from the bladder, the

air would fill the globe and the receiver together;

and in consequence of the increased dilatation

which the two cubic feet of air underwent, by

occupying the spajce of four feet, contained by

the globe and the receiver together, instead of

two, the expansible force of the air must be

diminished in proportion, and the mercury, instead

of being forced up to 29 inches, would

only rise to 14^. A second very judiciously

observed, at the time I was making some experiments

on the subject, that I only exhausted a

given quantity of air out of the receiver, which

sunk the mercury to the same level as the mercury

in the basin, and merely restored the same

AND EXTERNAL RESISTANCE. 303

column of air from the bladder back into the

receiver, which, consequently^ rose the mercury

as high as before. The observation was a

very just one, but it did not apply to the ob*

jection which he wanted to make ; for although

it was very true, that the same given quantity

of air entered into the receiver, as had been

pumped out of it, a separation existed, total

and complete, between the air in the receiver,

and the column of air external to it, if it were

therefore, the weight of the air, which forced

up the mercury in the tube, it could only be

the actual weight of the air alone which the

receiver contained, a weight of 20 grains, elevating

to the height of 29 or 30 inches, a column

of mercury of the weight of 30 Ibs. ! ! !” A third

sagaciously remarked,

” I do not pretend to

say, that it is the absolute weight of the air,

which causes the elevation of the mercury, but

it is owing to the regular and progressive increase

of weight, which the whole column acquires,

that the elastic, or expansible, foree of

air is increased at the bottom!!!” And this

knock me down argument, was supposed to be

proved, by an illustration which was made by

a fourth ;

” Take (he said) a spiral spring of

*ny height, place it on the mercury in th baion

apply a given force upon it, to overcome

the weight of the mercury, and the mercury

jnay by that means be raised to any given

x

PRESSURE IN THE AIR,

height ; run a nail through any part of the

spring hammer and fix it to a post, and cut

off the upper part of the spring, and the mercury

will be found to continue, by the pressure

of the inferior portion, as high as it was

before!!!” The distinction which I have

shewn to exist between expansibility between

elasticity and between weight, will, I

hope, show the error and futility of these observations

; the most elastic substance which

exists, whether steel or whalebone, is not elastic

per se ; if it presses at all, it presses by its

quantity only, either of gravity or of levity ;

when it presses by an elastic force, it is in

consequence of a power which has been externally

applied to it, by virtue of which the particles

of matter become compacted and compressed,

in proportion to the degree of external

power which has been employed ; the resistance

of the steel may prevent the force employed,

from extending beyond the first, or

second circle, or it may be so great as to overcome

the resistance of all the circles of the

spring altogether, and cause pressure to be produced

at the other extremity of the spring,

which pressure will make the mercury rise:

it will rise in proportion to the external force

employed ; and it will be kept at that point, if

the weight of the steel is sufficiently heavy to

balance the mercury, or the force sufficiently

AND EXTERNAL RESISTANCE. 307

great to raise it. The elastic force whicfr

the steel has acquired, is entirely from without

; and it ceases the instant that force is

taken away -the external force is the agent,

the steel is the instrument only; and it is by

the combination of both together that the effect

is produced ; the one without the other is uur

equal to the task.

With respect to expansible bodies such as

air, it is far otherwise ; it contains within itself

both the agent and the instrument instead of

acting, like elastic bodies, mediately it act$

immediately although an external force may

jcompress and condense it, into a smaller volume

; it was expansible before that external

force was applied. It acts, by its own inherent

power, independently of external influence,

wherever the least resistance prevails; and,

consequently, overcomes the weight of the mercury,

when it is placed at the bottom of a tube,

having in it an unresisting, because an exhausted

medium. It is becausethere is less resistance

in the medium above, than there is below that

the natural tendency in the air of expanding

equally in every direction, is rather directed

and diverted from the bottom towards the top;

that, the air, rather ascends than descends ;

and, consequently, that the observation made

by the former gentleman, is an erroneous one

” that the whole weight of the incumbent colunm

308 PRESSURE IN THE AIR,

of air, is the cause of its elastic force being

greater at the surface, than at the top.” It

appears to me, as far as I am able to comprehend

Mr. DALTON’S opinion upon this

subject, that we think very much alike. It is

His opinion, that the different gases, which constitute

the mass of our atmosphere, are mechanically

combined together; arid this, he conceives

accounts for the uniformity with which they are

mixed together in it, first, because the particles

of any individual gas, repel each other;

and secondly, because the particles of mixed

gases, neither attract nor repel each other ; they

are perfectly indifferent to each other, and are

not affected by their mutual proximity. When

they are mixed, they are diffused and joined

together, without separating, or uniting. Every

gas, by its elasticity,* or the repulsion of its

particles diffuses itself over the space in which

it is confined, neither attracting or repelling

each other, and therefore mixes without uniting

together. If, for example, there subsists on

the surfac^ of the earth, a column of oxygen

gas, it will rise to an indefinite height by its

elasticity ; if on the same surface, it be sup-

* It is really vexatious to see the best informed of our

philosophers, ignorant of the distinction which exists between

things, and, consequently, using false terms to express the

phenomena which they want to describe !

AND EXTERNAL RESISTANCE. 309

posed there rests a column of nitrogen gas, its

particles will equally recede, and become intimately

mixed with those of the oxygen gas.

Other gases, as caloric, or watery vapor, may be

thrown in, and the same arrangement of their

particles will take place, and thus on the

earth’s surface, there will rest so many columns

of gases, each intimately blended indifferent

to each other each supporting itself by its own

elastic power, and the inferior strata of each

only pressed by their own incumbent weight.

It is owing to the ignorance of the difference

which exists between expansibility and elasticity,

that many have been led to contend, that

unless two fixed points existed, it was impossible

for expansible bodies to expand ; the fact

is unquestionably true, with respect to elastic

bodies as they are called, but not with respect to

those that are expansible, expansible bodies

manifest their power without them -elastic bodies

derive the whole of their power from them.

A piece of steel, is only elastic through the medium

of compression at both ends. Air is expansible

at all points. The steam ofwater does not

derive its expansible force from the resistance

which it overcomes, from the sides of the kettle

in which it is enclosed the steam possesses

this expansible power without their influence;

it is the pressure of the steam which is able

MO PRESSURE: IN THE AIR,

to overcome the resistance of the sides of the

vessel in which it is contained.*

If we proceed to ascertain the relative

weights of equal volumes of atmospheric air,

when they subsist in the form of rain, or in a

dry state ; it will be found that the weight, and

inelasticity of the one, will far exceed the levity

and expansibility of the other.

It is to the error of measuring air by

weight, instead of expansibility ; and of subjecting

tb the same laws bodies whose nature

and properties were totally different

from each other, that a great proportion

of the false philosophy of the present day

is to be ascribed ; it was in subservience

to this false philosophy, of measuring air

by weight, that Mr. BOYLE himself, so deservedly

esteemed for eviery quality that was great

and good, in order to account for the rise and

* Pressure and resistance are words which are often confounded

together, but which, nevertheless, have opposite

meanings. Pressure is an active force Resistance a passive

quality. Thus, when I press my hand against the door, my

hand is active, the door passive. A horse which draws a cart,

is active, the cart passive. The difference in the nature of

each, may, perhaps, be better explained, by comparing resistance

with pressure, than pressure with resistance. The

door cannot press and squeeze my hand, although it can

resist the pressure ; it cannot act upon it, although it may be

acted upon by it. The cart cannot act upon the horse, although

it may resist the horse ; the one may, in fact, be

considered an active, the other a negative quality.

AND EXTERNAL RESISTANCE. 311

fall of the mercury in the Anaplometer, by the

known changes which the atmosphere undergoes,

concluded, that the weight of the atmosphere

was greatest when it was most serene and

clear ; and, on the contrary, that it was most

light, when most thick and cloudy and charged

with vapours ; that is to say, that it was most

heavy when it was most light, and most light

when it was most heavy ; the mercury rising

in the former case from 26 to 30 inches ; and,

on the contrary, settling in the other from 30

to 26 inches.

It was owing to the same errors from which

conclusions have been drawn, revolting to the

feelings and to the senses of the most ignorant,

that the pressure of the atmosphere upon bodies

situated near the surface of the earth, was the

pressure of weight, not of expansibility; and

that the weight of the incumbent column was

said to be the cause of that compression ; insomuch,

that if there were a pit dug in the bowels

of the earth, 33 miles in depth, the air at

the bottom would be as dense as water, but if

it were 50 miles deep, the air would, in that

case, be as dense as gold itself. It was in furtherance

of this false philosophy, that it was

affirmed, and continues to be believed at this

time as a true article of philosophical faith,

that the absolute weight, or perpendicular pressure

downwards of the atmospheric column

312 PRESSURE IN THE AIR,

from the top to the bottom, is in the proportion

of 15 or 16 Ibs. to every square inch of surfaceand

as there are 144 square inches to every

square foot, these :must consequently sustain a

pressure of weight equal to 2,880 Ibs. supposing,

therefore, that a man in an erect posture covers

a surface commensurate to a square of 16

inches, (a calculation very moderate,) it must, in

that case, follow, that the perpendicular pressure

upon him, is equal in weight to 2,880 Ibs.

But, alas ! if he should have lips thick nose

flatcheek-bones prominent ears expanded

hat broad-brimmed, a parasol to keep off the

sun, or a parapluie to shelter him from the rain,

the weight must, in that case, be as great, as

it is when he is in a recumbent position ; or

when the superficies of his body may be consequently

supposed to be increased, at least, to a

square of eight feet; it is affirmed, and very

justly affirmed, if the positions were true from

which these conclusions are drawn, that such

a one must sustain a weight of 15,370 Ibs. that

is to say, more than seven tons weight, for his

Ordinary load!!! It was from data such as

these, that Mr. COTES, and others, conceived

that they had been able, with precision, to calculate

the absolute pressure of dead weight of

the whole ambient air, impending over the

globe in general, and this country in particular.

The superficial surface of England, is

AND EXTERNAL RESISTANCE. 313

-estimated at 39 millions of acres, the weight

of the atmosphere upon it, ought consequently,

to press with a force equal to

fifteen hundred thousand millions of tons,

(1,576,870,000) and the weight upon the whole

surface of the world, is estimated to be equal

to a globe of solid lead, 60 miles in diameter.

Whatever reprehension such conceits might

merit, if they were merely intended to astonish

the ignorant, by an idle display of the wonderful

powers possessed by natural means, they

become absolutely ridiculous, and laughable,

when they are maintained as fundamental

truths by the wisest of the wise.

In order that the fanciful consequences which

have been so learnedly described, should ensue,

the natural condition of things as it actually

exists, must be destroyed, aad an inverted

state of it, be fancied and whimmed ; instead

of the atmosphere subsisting in a state of equilibrium,

it ought to press ^unequally in particular

directions ; ipstead of subsisting in

open space, it ought to be confined in close

vessels ; instead of being denser at bottom

than at top, it ought to be denser at top thai*

at bottom ; and, finally, instead of moving, as

we do in a plenum, we ought to move and to

breathe (if I may be allowed the folly of sucfh an

expression) in a perfect and a perpetual vacuum.

If this inverted order of nature, and of

314 PRESSURE IK THE Alfc,

things, actually were what it actually is not ;

the various estimates which I have above detailed,

might then be applied. Mr. Cote’s calculation

might be true, that the circumambient

air, was in weight, upon the surface of the

earth, equal to a leaden globe 60 miles in diameter

; and that \he weight of 15,370 Ibs. pressed

on our frail and debile bodies. It must,

however, be evident, that a weight such as this,

would lacerate to atoms the lungs of all animated

beings ; and explode every part of the

system to which it obtained admission that

the fluids would be pressed and squeezed out

of the exhalent vessels, and that air would

issue out of every pore.* So far, therefore,

from measuring by its weight, the degree of

pressure which the atmosphere exerts, it is

by its expansibility alone, that its effects are

produced, pressing with the greatest force

when it is least ponderable, and when it is

most ponderable, Exerting the least pressure;

that is to say, air is most expansible when least

ponderable ; and least ponderable, when most

expansible. That this is the fact will appear,

if we proceed to ascertain the relative weights

of equal volumes of atmospheric air, when they

* I beg to have it understood, that these calculations are not

my own, but those of others, which I offer in order to show

how true conclusions can be drawn from false principles, and

error substituted for truth.

AND EXTERNAL RESISTANCE. 313

Subsist in a vaporific, or gaseous form, in the

form of rain, or in a dry state : it will be found

that the weight and inelasticity of the one, will

far exceed the levity and expansibility of the

other : in the one case, the mercury in the tube

sinks in the other it rises, while the degree of

depression of the mercury is found in a great

measure to depend on the decompositions,

which the atmosphere undergoes, from dryness

to moisture from a calm to a storm ; its elevation,

on the contrary, proportionably takes

place, from moisture to dryness from astorm to

a calm. From the experiment of Perrier, which

I have detailed, and which has been repeated

by different metereologists, it appears, that the

elevation of the Anaplometer, to 3,000 French

feet, from the surface of the earth, occasioned

a depression 3:1-8 French inches of the mercury;

from whence it was concluded, that

3 : 1-8 inches of mercury, weigh as much as

3000 feet of air, and 1-10 f an inch of mercury,

as much as 96 feet of air ; when, therefore,

the mercury stands at 30 inches, near the

sea shore, it is conjectured, that, if it were

raised to 300 times 96 feet, or a little more

than five miles, the mercury in the tube would

sink to the same level in the basin, as it is

found to do, in the

receiy^,

after the greatest

portion of air which it captained, has been exhausted

out of it. In order to make the calcu316

PRESSURE IN THE AIR,

lation as precise as possible, it is said, that as

the weight of air is to that of mercury, as 1 is

to 10-800, it must, of course, follow, that if

the weight of the atmosphere, be sufficient to

raise a column of mercury to the height of

30 inches, the whole atmospheric colum~

must be 10-800 greater in weight; and,

consequently, that the whole extent of the

atmosphere, from the bottom to the top, cannot

exceed five miles one quarter. After

the proofs which I have advanced, in order to

show that the elevation of the mercury in the

tube, does not proceed from the pressure of

weight, I shall merely observe, that these limits

were proved to be false, by the facts which the

authors themselves produced ; they were proved

to be false by the frequent appearances of

meteors, of those bodies which cannot exist

without the existence of air, at the elevation of

80 miles from the surface of the earth. In the

month of March, 1719, a meteor was seen, by

Dr.HALLEY,at the computed height of73 miles,

whose diameter was 2,800 yards, or upwards

of a mile and a half; and whose velocity

amounted to 350 miles in one minute. In latter

times meteors of a similar nature have been

observed, whose magnitude and motion, as well

as distance from the earth, was far more considerable.

The 18th of August, 1783, one of

these was discovered, whose distance from the

AND EXTERNAL RESISTANCE. 317

earth was estimated at 100 miles ; and whose

velocity was not less than 1000 miles in a minute

of time. The indefinite elevation to which

the atmosphere extends, is more especially

proved by comets, by those meteors which

surpass every other of which we have any

knowledge, in magnitude and motion, as well

as in brilliancy and transparency, the sun alone

excepted. Instead of being rounded, like common

meteors, they are, for the most part, distinguished

from all other bodies, by having a

large mass of matter attached to them, in consistency

so semitransparent, that the smallest

star can be distinguished through it, in color

smoky, or clouded, and in figure striated and

fibriated like hair ; it is from this peculiarity in

the appearance of this portion of the whole,

that the name of Comet has been derived, from

Coma-Hair.

When we reflect on the facts which I have

detailed, of the wonderful power of expanding

which air possesses, when external resistance is

weakened ; and more especially if the supposition

entertained by Sir I. NEWTON be true, that

a cubit foot of air, carried to the elevation of

one semidiameter from the surface of the earth,

would expand as far as the orb of the planet

Saturn, we are bound to believe, that the calculations

which have hitherto been made, and

which confine the elevation of the atmosphere

318 PRESSURE IN THE AIR,

to five miles only, are far too limited ; and 01*

the contrary, that it has the power of expanding

to an indefinite extent.

Instead of the different gases of which the

atmosphere is composed, obeying the lav of

relative weight,* they act in direct opposition

to it. If gases acted by virtue of their weight,

instead of the atmosphere being one united

whole, composed of parts, whose essential properties

are alike, but whose secondary, or chemical

qualities, are different ; it would consist

of separated parts, out of which one disjointed

and tesselated whole was formed. Instead of

being, as it is found to be, of one uniform

homogeneous nature, combined together in a

manner the most intimate and imperceptible

the parts would separate into different layers,

or strata the lightest would form the summit,

the heaviest gas the base of the whole : we

would have hydrogen at the top oxygen and

nitrogen in the middle, and carbonic acid at the

bottom. If we were to have what we actually

have not, the human race, in general,

* I beg to observe, that as there is no such thing as absolute

weight; and as weight is ever to be considered the measure

of the density of one body, with relation to the rarity of another,

the terms relative and absolute, ought to be entirely abandoned

; and that when we speak of a body being heavy, or

Jight, it is either dense, or rarer, than another one.

AND EXTERNAL RESISTANCE. 319

and herbivarous animals in particular, would

be suffocated and poisoned as effectually as if

they were exposed to the vapour of the grotto

del Cane, or of the lake of Averno. A beneficent

Providence has directed it otherwise : the

weight of different gases is entirely overcome,

by the equal degrees of expansible power

which they separately possess.

If the chemical properties of these gases are

examined, they will be found very different

from each other. The properties of nitrogen

would seem to be rather of a negative, than of

a positive nature; it is neither absorbed by

pure water, in any sensible quantity, neither

does it render lime-water turbid, or turn it

white, it produces no change in vegetable

color, and is totally unable either to support

combustion, or subserve to the process of respiration.

Oxygen, on the contrary, is the principal

agent in the production of combustion, and

when mixed in the proportion in which it is generally

found to exist in the atmosphere, is best

adapted to promote, and to subserve to the process

of respiration. It is obtained from different

substances, by factitious and unnatural

means ; it is disengaged by the operation of an

ardent fire, from nitre, from manganeze, and

other bodies, when closely confined in a retort.

It is very generally excreted during the day by

320 PRESSURE IN THE AIR,

vegetables in general, more especially when

they are exposed to the free influence of the

solar rays.*

Although it is very true, that vegetables, during

the day, excrete a quantity of this particular

gas ; they are known to absorb a large

proportion of it also. In the oxydation of metals,

the full quantity is separated from the

atmosphere, by the fire, as is given out by the

oxyde ; and the intensity of fire which it is necessary

to excite in order to obtain oxygen gas,

is not found to exist, in the ordinary state of

things. Means, therefore, such as these, are

altogether, inadequate and insufficient, to account

for the actual existence, much less for the

reproduction of the immense quantity of oxygen

gas which is perpetually separated from the

atmosphere by animals and vegetables, during

* If further evidence of the wretched state of our Nomenclature

were necessary, I should dwell particularly on the

term Oxygen Gas. Oxygen means sour, and is supposed to

comprehend the solid base, or gravitating matter, and the term

Qxygen Gas, the actual existence of this base, in a airiform

state ; it is imagined by chemists, that it forms the principle

of all acids, and of acid combinations ; and from this circumstance

it is, that its name is derived : it would, however, seem

very unscientific to call this gas, Oxygen gas, or sour gas,

when it neither is sour to the taste, or produces on other bodies

any of those effects which acids are prone to do, and bj

which they are distinguished from other bodies.

AND EXTERNAL RESISTANCE, 32 J

the process of respiration, and consumed in the

generation of ignition, and of combustion.

It is very probable that these means may form

a subordinate, and auxiliary part, i the production

of oxygen gas. The whole column of

the atmosphere, however, long before this advanced

period of the world, would have been

contaminated, and rendered unfit for the support

of animation, and the generation of ignition,

if there did not exist, in the great laboratory

of nature, some means, by whose agency

the whole chaotic mass, of which the atmosphere

is composed, both solid, liquid, and

gaseous,–animals in their living state, as

well as animal and vegetable exuviae, and poisons

the product of both, become purified

and regenerated through the process of decoraposition.

On a faithful review of the whole, it appears

most probable, that it is by the agency

of the solar rays, that this regeneration i

accomplished, and oxygen gas formed ia

the abundant quantity in which it is found.

It may, indeed, become a question, which

future experiments may solve, it may, I

say, become a question, whether the resolution

of particular parts of organised bodies^

both animal and vegetable, into hydrogen and

carbonic acid gas, may not be among the first

changes which these parts undergo, by the

322 PRESSURE IN THE AIR, ETC.

processes of putrefaction and fermentationthat,

as those parts are resolvable into these

gases, so these gases (in consequence of certain

processes to us unknown) may, in union with

oxygen gas, become convertible into that immense

mass of nitrogen, or azotic gas, of which

the greatest portion of the atmosphere is composed

;< that as animal and vegetable matter,

constitutes the base of hydrogen and carbonic

acid gas, so carbonic and hydrogen gas, may

constitute the base of nitrogen. The noxious

qualities which these gases separately possess,

become so neutralised, if I may be allowed

the expression, by the new combinations which

they have undergone, that they are ultimately

lost ; insomuch, that the atmosphere altogether

becomes fitted and adapted to answer the end

for which it is designed, the nourishment and

support of the animal and vegetable creation,

and the base from whence illumination, in general,

is produced, and color in particular

CHAPTER XVI.

ON COLORIFICATION IN GENERA^,

On the means % which Color is produced,

the sourcefrom whence it i$ Derived,

ALTHOUGH the art of analysis irj these latter

days has attained considerable degrees of perfection,

and a multitude of tests have been discovered,

by the aid of which, a variety of bodies

have been decomposed, and simplified to

a greater extent than before; it must, nevertheless,

be acknowledged, that none of the

skilful artists, who have labored in t)ie pursuit,

have as yet been able to exhibit to our view,

the real constitution of the primary particles of

matter; insomuch, that natural philosophers,

Sit this moment, either confess their total ignor

jrance, or are at variance with each other on

324 COLORIFICATION IN GENERAL.

subject. When we, however, reflect on the

actual state of things, as they exist in this world,

in which animated beings are fed and nourished,

not only by a large proportion of the common

matter of which it is composed, but by the

materials which are produced from the -decomposition

and corruption of living matter also ;

and that a variety of new combinations are constantly

taking place between the different parts,

every allowance ought unquestionably to be

made, for the imperfection which exists. It is>

probably, owing to an ignorance of the properties

which essentially belong to different species

of elementary matter, that attention has been

exclusively bestowed on those which are secondary

and accidental ; they are, in fact, those

which are most cognisable to our senses, and

which excite on them the sensations of hardness,

and of softness of figure, and of color

of flavor, and of sound of heat, and of cold.

It must not, however, be inferred, because

substances, various and extraneous, often alloy

gold, that the pure metal does not subsist in its

individual and virgin state ; or that light, water,

and earth, have not an elementary existence,,

because different bodies are generally found,

either chemically combined with them, or mechanically

diffused in them. A contrary conclusion

can only be formed from the false

trOLO&IFICATION IN GfcNE&AL. 325

Assumption, that the great first Cause, who

created the universe, and all that is therein,

created confusion before order imperfection

before perfection the compound before the

simple ; it is far otherwise ; all the secondary

qualities of bodies which exist, are produced

by the union and combination which take

place, from things simple and elementary : and

in order to have a scientific knowledge of the

phenomena which nature presents to our view ;

in order to know the causes of these phenomena,

(which are nothing more than effects produced,)

it is absolutely necessary, to have a clear apprehension

of the simple, before the con>

pound- of expansibility, before expansion of

fluidity, before solution of light, before color

of vitality, before organisation of extension

in general, before figure in particular. The

phenomena which the secondary properties of

matter display, are the means by which those

which are primary and essential are explored;

they are the steps by which we are enabled to

ascend from the last to the first of things,

from the effects, to a knowledge of the cause ;

a branch of knowledge which, it is probable, the

art of analysis cannot attain, because analysis

cannot resolve that which is irresolvable, but

which, nevertheless, may be apprehended by

abstraction and contemplation. The defective

COLORIFICATION IN GENERAL.

state of the analytic art, equally extends to the

synthetic ; although a multitude of compound

bodies, can factitiously be formed from those

that are simple ; no effort of human ingenuity,

has been able to discover the means by which

the pure colorless solar rays, in their passage

through the atmosphere, acquire properties

which are totally different from those which

they originally possessed ; and have the power>

in consequence, of exciting on the optic organs

of animated beings, the sensations of illumination

in general, and of color in particular. The

phenomena which these colors display, have

been particularly examined by Sir ISAAC NEW*

TON, and are amply detailed in his celebrated

Lectiones Opticce, as wr ell as by a variety of

others ; and are the objects which the science

of optics is intended to unfold. The theory of

colors, which he entertained, was founded on

the assumption, that the sun was a globe of

fire, emitting rays composed of seven different

colors, which were separable from each other

by means of the prism ; that these seven colored

rays* instead of being compounded, were

original and simple ; and that they constituted

the sources whence the infinite variety of colors

which exist throughout the whole system of

nature, are produced. It was his opinion also,

that all bodies have the property of absorbing

COLOR1FICATION IN GENERAL. 32?

the solar rays, although many bodies have not

the power of emitting them alike ; that is to

say, all bodies do not absorb, or reflect, all the

rays indiscriminately ; some bodies absorb one

colored ray, other bodies another, while they

reflect the rest; and that to the difference

of capacity in different bodies, of absorbing

particular rays, and of reflecting others, the

variety of colors in different bodies, is supposed

to be owing. A red body, for example,

reflects from its surface the red rays,

and absorbs the rest; a green body reflects

the green rays, and absorbs the rest ;

a white body is supposed to reflect all the rays,

and to absorb none ; and a black body to

absorb all the rays, and to reflect none; or, in

other words, the different colors which different

bodies assume, are supposed to depend on

the want of affinity, which particular bodies

possess for particular rays, by means of which

those rays become reflected from the body on

which they fall; that while no individual ray,

but the whole of the primary colors, reflected

and emitted to our organs of sense, are absolutely

necessary in order to exhibit the color

of WHITE ; so, on the contrary, it is supposed,

that when the whole of the incident

rays are absorbed, and suffocated in the

body on which they fall, they are reflected.

828 COLORIFICATION IN GEKERA5L,

and refracted within it, instead of being reflected

out of it; and that the color of black is thus produced.

Great as the authority may be, from

whence these opinions are derived, they appear to

be contradicted by the different qualities of color,

which every individual substance seems to pos*

sess. If the assertion were true, that the color

of a body altogether depends on the reflection

of particular rays, and the absorption of the

rest , if a body be green, because it reflects the

green rays, but absorbs the rest, if a body

be red, because it reflects the red rays, but absorbs

the rest; it must, evidently, follow from

these assumptions^ that the body which we

suppose to be red or green, is, ipso facto, inherently

and absolutely of every other color,

but red and green.

We must conclude from thence that the body

which we call WHITE, because it reflects all the

rays and absorbs none, is destitute of color altogether;

and, on the contrary, that thebody which

is knownby thename ofBLACK, becauseit absorbs

all the rays and reflects none, is absolutely and

inherently of every color but a black one. Ab*

sorbing all the rays and reflecting none, as the

black body is supposed actually to do, it

is impossible that any knowledge could be

obtained by the eye, of the figure and color

of the body in which all the colors were im*

COtO&IFlCATION IN GENERAL. 329

With respect to vision, a body,

such as this, would be a perfect blank,

invisible to the eye, and only cognisable by

the resistance which it gave to the sense of

touch.

The same consequences would ensue with

respect to what is called WHITE. If a body

appear to be white, because it reflects all the

rays, and absorbs none of them; it is impossible

that any knowledge could ever be obtained

of a white body by the eye ; since, in such a

TOse, it must be destitute of color altogether.

I would, however, ask whether there be any

solid ground for supposing that the different

impressions made on our organs of vision by

the particular rays which flow from particular

bodies, are not equally referable to them all, without

any exception. I would ask whether any

exception ought to be made with respect to jet

‘and to snow? Whether the rays which flow from

both, by which the impressions on our optic

sense excite the sensations of white and black,

havenot an actual existence within those bodies,

or at least on their external surfaces, as much

as on those ofgold or indigo ? Whether the white

wax and the black wick of which my candle is

composed, are not as obvious to the eye, and

as referable to the same cause, as the red flame

that issues from it ? I would ask whether that

hypothesis be built upon a legitimate assurop330

COLORIFICATION IN GENERAL.

tion, which makes the body which is called

black, to arise from the absorbtion of all the

rays, and, at the same time, affirms the substance

which reflects all the rays, and absorbs

none, to be the cause of white; making,

in fact and in truth, black to be white, and white

to be black. Much less is it justifiable to con^

elude that neither black nor white are colors.

Instead of supposing that the infinite variety of

colors and of shades which the whole ofanimated

nature displays, that the black pigment which

gives to the eyes of animals in general, and of

the human species in particular, a character so

marked and striking, and that the beautiful bloom

ofred and of white with which the complexion of

the fairer sex is adorned, wanning the coldest

heart with sentiments of admiration and of delight,

proceed from the existence, within, of

original health and beauty : on the Newtonian

hypothesis, we must, on the contrary, conclude,

that the whole of our perceptions, in these’particulars,

are founded in delusion and deceit:

we are bound to conclude that the most beautiful

complexion of the most beautiful woman,

appears to be what it is not in reality : that the

shades of red and of white mingled together in

such admirable proportions, as they often are,

instead of existing as parts separated from

the blood, and deposited on the skin, from

whence they are conveyed to our eyes by the

tOLORIFlCATlON IN GENERAL. 331

agency of pure and colorless light, never had

an existence on the skin, but that they are

repelled and excluded from it; and that

it is polluted and defaced by the rays alone

which are absorbed within, and not reflected

without, viz. the orange, the yellow, the green,

the violet, the indigo, the purple, the black.

So far, however, from subscribing to these

opinions, however great the authority may be

from whence they are derived, [ feel it my duty

to protest against them, and endeavour to expose

the absurdities to which they lead : they

have, I conceive, been occasioned by an ignorance

of physiology, by not knowing the relation

which exists between the sensitive principle

within, and the substance without, by

which sensation is excited and produced. Instead

of ascribing sensation to the receiver, it

has rather been referred to the thing received,

and impression and sensation have thereby been

confounded together.

Instead of supposing that the pure solar rays

(which in their simple and uncombined state, I

have endeavoured to shew are colorless and invisible)

are colored originally and essentially ;

or, that the infinite variety of colors which AVC

behold, are formed out of the prismatic alone,

I conceive it far more reasonable to conclude,

that the pure solar rays are the carriers and the

agents only ^ that not only the formation, but

332 COLORIFICATION IN GENERAL.

the diversity, of color, principally depends on

the quality of the base with which colorless

light has combined ; that it is owing to this

combination which has taken place between

both, that a new substance (a tertium quid) is

formed, which is colored since it is visible ;

and, which is visible, because it is combined ;

the properties of which are very different in

their combined, from what they were in their

simple elementary state. The matter of light

from being colorless, becomes colored, from

being invisible, it becomes sensible, from being

transparent Only, it participates, in an eminent

degree, in the opacity and quality of the

base, with which it has united ; the result of

which is the production of color. So long.,

therefore, as the eye becomes illuminated by

any object whatever, that object must be considered

to be colored. Illumination constituting

the genus, of which color is the species. In

order, therefore, that vision should exist, it is

necessary that the rays of color which are transmitted

or reflected from different bodies, should

unite, in the eye, in the same order as they

exist in the substances from whence they have

issued, or whence they have been reflected.

The change of color, which different bodies

undergo, by exposure to the solar rays, and

more especially the facility which we possess,

of collecting these colored rays by means of

COLORIFIATION IN GENERAL. 333

proper glasses, and of reflecting them in their

colored state on other bodies, appears to prove,

in a decided manner, that a union has taken

place between the rays of light, and the bodies

on which they have impinged. It is with a

view of preventing this union between them and

the furniture of our apartments, that their introduction

is prevented by blinds and shutters;

and I need not add, that the loss of color, by

exposure to the solar rays, in ribbands which ladies

employ to ornament their dress, is to them

a constant source of lamentation. It is with a

view of preventing the deleterious influence of

light on colored bodies, that various substances

are combined, by painters and dyers, with their

coloring matter, in order to fix the colors, and

to prevent them from flying off. That the loss*

of color, which we behold different bodies undergo

by exposure to the solar rays, proceeds

from their influence, independently of the heat

which subsists in them, is most obvious ;

little or no change of color takes place, although

those bodies are exposed to a temperature

much higher in degree. If colors are not immediately

derived from the solar rays, it may reasonably

be asked, to what sources are they to

be referred? I would answer ; to the infinite

multitude of bodies which exist, not only living

and dead, but common also ; these may be considered

as the radicals or base, by the union of

334 COLORIFICATLON IN GENERAL.

which, with pure, colorless, invisible light/-

colorless and invisible light becomes light, visible

and colored. We behold colored light

evolved, in the most obscure nights, from animals

of the feline race in general, from fish,

from the glow worm, from pyrophori,

from the Bolognian stone, and from different

kinds of crystals and of diamonds. We see

colored light perpetually radiating from bodies

in a state of combustion : the quality of the

color seems altogether to depend on the nature

of the materials of which the base is composed,

subservient to that process ; different kinds of

coal and of peat, always produce a peculiarity

in the color of the flame. The same variety in

the color of the flame subsists in our lamps and

candles, whether they are made of oil, of tallowy

or of wax ; and it may also be observed,

that by some experiments that were made on the

tallow ofan old woman, who had been condemned

to suffer death as a malefactress, it was found

that the candles which were made from it, gave

out a flame of a beautiful blue color. Spirit of

wine imparts a blue, the green calx of copper,

a green, and the white calx of zinc, a flame

as white and as bright as it is possible to conceive

; while, on the contrary, the smoke or

black flame which issues out of many furnaces,

is often as black as jet. This combined light

is often proved to exist in the atmosphere, by

COLORIFICATION IN GENERAL. 335

the different colors, which different bodies situated

in it, are found to display, by the clouds,

so diversified in appearance, by the electric

fire, as well as by different parts of the planetary

system. Who is there, that has not observed

the flery color of the rising and the setting sun,

and the pale and colorless appearance which it

assumes in the middle of a clear day? How is it

possible, with all these facts constantly before our

eyes, not to admit, that it is owing to the union

which has taken place between the solar rays

and the matter of the medium through which

they pass, that these colors are produced. No

proof, perhaps, is more strong, of the uniformity

existing in the composition of the atmospheric

matter, by which the medium above is

filled, than the uniformity in the rays of color

which are formed by the passage of the rays of

light through it, and which are separated from

each other by means of the prism, and thence

called prismatic colors. It is for the purpose of

describing the different mechanical phenomena

which these different colors display, that the

science of optics is especially designed, the leading

propositions of which are as follows.

Def. 1. Light. (Color it ought to have been

called.) Light is that, which proceeding from

any body to the eye, produces the perception

of seeing. 2. A ray of color is an exceedingly

small portion of light (or matter) as it comes

336 COLORIFICAT10N IN GENERAL,

from a luminous body. 3. A body which is*

transparent, or affords a passage for the rays of

light, is called a medium. 4. Rays of color,

which coming from a point, continually separate

as they proceed, are called diverging rays.

  1. Rays which tend to a common point, are”

called converging rays. The divergency or

couvergency of rays, is measured by the angle

contained between the lines, which the rays

describe. 6. Rays are parallel, when the lines

which they describe, are parallel. 7. A beam

of color, is a body of parallel rays : a pencil of

rays, is a body of diverging or converging rays.

8, The point from which diverging rays pro-*

ceed, is called the radiant point ; that to which

converging rays are directed, is called thefocus.

  1. A ray bent from a straight course in the

same medium, is said to be inflected.

Laws of refraction, or the rules which different

rays of color obey, when they pass through

different media.

  1. A ray of light, bent from a straight course,

by passing out of one medium into another, is

said to be refracted.

  1. The angle of incidence, is that which is

contained between the lines described by the

incident ray, and a line perpendicular to the

surface on which the ray strikes, raised from

the point of incidence.

  1. The angle of refraction, is that which is

COLORIFICATION IN GENERAL. 337

contained between the line described by the

refracted ray, and a line perpendicular to the

refracting surface, at the point in which the

ray passes through that surface.

  1. The angle of deviation, is that which is

contained between the line of direction of an

incident ray, and the direction of the same ray

after it is refracted.

Def. 1. A ray, turned back into the same

medium, in which it moved before its return, is

said to be reflected.- 2. The angle of reflection,

is that which is contained between the line

described by a reflected ray, and a, line perpen-,

dicular to the reflecting surface at the point of

reflection. 3. The angle of reflection is equal

to the angle of incidence.* Vid. Enfleld.

* A Latin translation of the Optics of Ptolemy, a work

which was supposed to be entirely lost, as we only possessed

a few lines of it, which have been transmitted by Bacon, has

lately been discovered by Count LAPLACE, in the imperial

library at Paris. The translation is by Ammiratus Eugenius

Siculus. The first book is wanting, as it was wanting in the

original Arabic, from which Ammiratus made his translation.

From this work, it appears that Ptolemy was well acquainted

with the effects and laws of refraction, and that, in this respect,

he was even more advanced than Tycho, Kepler, Hevelius,

and all the astronomers till the time of Cassini, who was

the first among the moderns that asserted that refraction did

not entirely cease up to the zenith. But what is still more

curious, and was never in any manner suspected, is that Pto-

Z

338 COLORfFICATION IN GENERAL.

The motions, which the different colorific

rays describe, in passing through different media,

are so regular and uniform, that these

motions are reducible to mathematical principles,

and can be illustrated and proved by mathematical

rules. Of the utmost importance,

it must, nevertheless, be confessed, is the distinction

which exists between the illustration of

those phenomena, by mathematical rules, and

the causes by which those phenomena are produced.

Each of these objects has its own

principles, and he who confounds the one with

the other, involves himself in error and in confusion.

To the mathematician, the office be^

longs of ascertaining the quantity of matter

which the different rays contain, and the extent

of space which they fill, the velocity they

describe, and the degree of mechanical effect (if

any) which they produce on other bodies. To

the chemist, the province belongs, of exploring

the quality of the material? of which different

colors are composed, and the best means by

which they may be factitiously prepared. To

the physiologist and metaphysician, are the

higher duties allotted, of ascertaining the rela-

Jemy was also as well acquainted as we are with the refraction

which light undergoes, in passing from air into water or into

glass, and that he has given tables of it for every ten degrees

of the angle of incidence.

C0LORIFICATION IN GENERAL.

tion which subsists between impression ?tnd

sensation, between the substance without,, &n$

the sensitive principle within, between the

primary and secondary qualities of matter

Without a previous knowledge of these subr

jects, optics, or the laws of vision, can never

be scientifically understood ; or the nature anc|

cause of cojor be ascertained.

If sensibility be separated from animation,

and animation from matter, all the secondary

properties of matter, are at once obliterated

?

and lost ; solids are bereaved of their figure,

liquids of their flavor, gases of their sound, and

light of its colors. Except the attribute of ex–

tension, which is common to the whole, nothing

is left to solids but their resistance, to liquids

but their mobility, to gases but their expansibility,

and to solar rays, nothing but their,

motion. Ignorant of these truths, the generality

of chemists haje confounded the sensation

with the impression, and mistaken the one for

the other, not only with respect to the different

secondary qualities which I have described, but

more especially to those by which the sedations

of heat and of cold, are excited, and which I

shall designate by the generic name of TEMPS.-.

HATXJRE.

CHAPTER XVII,

ON THE MATTER OF TEMPERATURE IN GENERAL,

AND OF REFRIGERATION IN PARTICULAR.

IT is to be lamented that the English have conceded

to the French chemists, the term by which

that matter is designated and known, which

has the power of exciting the sensation of heat

or warmth to animated beings in general, and

of expanding common matter in particular ; and

both, I conceive, are blameable for having

changed the word fire, feu, for that of caloric.

Feu, like fire, is the abstract word, expressive

of the abstract thing ; whereas the word caloric*

by conveying with it the idea of chaleur, which

in English means heat or warmth, would rather

seem to confound together the sensation which

is felt, with the substance by which the sensation

is excited, as if both subsisted in one and

the same subject. The Romans preserved the

distinction between both ; between ignis or fire.

REFRIGERATION. 341

the thing signified, and calor, or the sensation

of heat which was produced in consequence of

the impression. The same observations equally

apply to the different bodies by which the

sensation of cold is excited.

Such is the mutable nature of the organs of

sense, whidi animated beings in general possess,

that the sensations either of heat or of cold

which they feel, must ever be considered a test,

the most uncertain of the different degrees of

temperature existing in different bodies ; the

same quantity of matter of temperature, applied

to the organs of sense, not only produces

different sensations to different individuals, but

to the same individual at different times. If a

man plunge his hand into a basin of water, at

the temperature of 50 of the present standard,

and remove it into water of the temperature of

100*, the former will feel cold, the other hot; and

ifhe remove the one of 50 to one of 33, the one of

50, which felt cold at first, will feel hot, when

compared to what it was when situated in that

of the temperature of 100. The most certain

means we possess of ascertaining the different

quantities of the matter of temperature existing

within a given bulk, consist in the different degree

of dilatation and of contraction, occasioned

to bodies exposed to the influence of that temperature,

under the different states of refrigeration

and of combustion, as they may be called.

$42 REFRIGERATION.

instead of examining the various causes, iby

the operation of which different substances ac^

quire different properties; in consequence of

new ‘combinations wlich take place between

them ; how aether is volatilised into vapor, and

ivater consolidated into ice and snow, by means

of which these bodies have the wower of exciti.

ing the sensation of cold in animated beings in

general : chemists have come to the unanimous

-resolution of considering cold as a non-entity;

dependent altogether on the privation of fire, or

caloric. I would, however, put it to the feeU

ings of these gentlemen, whether snow or ice*

applied to bodies in which those sensations are

produced, have not an actual existence, as much

as those which proceed from a flame of fire by

which the sensation of heat is excited : not by

the abstraction alone of fire or caloric from the

body, but by the palpable application of ice to

  1. I would ask, whether the effects which are

produced during the winter in the polar regions

as well as in other countries, where we behold

liquids converted into a solid form, water become

ice, vegetation suspended, animation

rendered torpid, and both by mortification

decomposed and destroyed : I would ask, whether

it be not reasonable to conclude^ that these

effects have been produced by the new modification

of matter that has taken place: and whether

it must not appear somewhat strange to men of

REFRIGERATION. 343

‘Common feelings, who possess common sense,

to be told, by the most enlightened chemists

and experimental philosophers, as they

call themselves, that none but ignorant

fools, if any there are so foolish, dare to

think so.*

So long ago as the year 1684, was found in

the essays of 1’Academie del Cimento, a paper

which has been translated, to shew the nature

and properties of cold ; and the recent experiments

lately made by Mon. PJCTET decidedly

prove, that what is called cold, may as easily

be reflected from snow and ice, as what is called

heat, from aflame of fire. Pictet placed two

concave mirrors, made of tin, at the distance of

ten feet and a half from each other ; a very delicate

thermometer was put into the focus of

one, and a glass mattrass, full of snow, into the

focus of the other ; the mercury in the thermometer

immediately sunk several degrees ; and

when the mattrass was removed, which contained

the snow, when the rays of snow ceased to

* I must refer the reader to the chapter on Sensation. I

hope that he is, by this time, sufficiently acquainted with the

difference which exists between impression and sensation, not

to know, in speaking of ice being cold, and of fire being

hot, that these bodies are not cold or hot essentially or per se,

but only cause impressions which excite the sensations of cold

and of heat.

344 REFRIGERATION.

be reflected upon the thermometer, the mercury

rose to the temperature of the surrounding medium.

The degree of cold, in another experiment,

was increased, by pouring upon the snow

some nitric acid; the consequence of which

was, that the mercury in the thermometer,

which was exposed to the focal point, sunk six

degrees lower than before.

Mr. WALKER, who spent much time in prosecuting

experiments, with a view of ascertaining

the greatest quantity of cold, that could be

Artificially produced, found, that by mixing two

parts of concentrated nitrous acid, by weight,

and one part of water, and by adding to this

mixture, when cooled to the temperature of the

atmosphere, of Glauber salt* Ibiss. and of

sal ammoniac, Ibiss. I say, that on adding the

Glauber salt to the nitrous acid, the thermometer

fell 52 degrees ; that is, from 50, which it

was at before, down to 1 ; and on adding the

sal ammoniac, it sunk to 9 belowr 0. By these

means, Mr. Walker was enabled to freeze

quicksilver, at the time when the mercury was

at 45. in the air.

The union of sulphuric acid, ofspirit ofwine,

and various other substances, with snow, will

produce a low temperature to an intense degree*

and by a proper management of artificial means,

ice may be formed for the luxury of man, in

REFRIGERATION. 345

those countries in which the temperature of the

climate is generally very high.*

Although the temperature of the air varies in

different countries, as well as in the same country

at different seasons, it may, nevertheless, be

considered a general truth, that when the temperature

is increased on the plain surface, the

minimum of low temperature prevails at the

polar regions, and progressively becomes higher

towards the line of the equator, when it may

be said to have attained its maximum. The

temperature of Siberia and of Africa are as

different as they are distant from each other;

in the one, it is found, according to the present

scale, as low as 5 of Fahr. t in the other, as

high as 114 degrees: although this great difference

of temperature exists on the plain surface,

a greater uniformity prevails, in the upper parts

of the firmament, insomuch that in ascending

the highest mountains of the world, at whose

* At Benares, in the East Indies, the manufacture of ice is

carried on to a very large scale; a piece of ground is divided

into plots four or live feet wide, the borders of which are

raised four inches above the central surface: dry straw is

placed on this part, and a number of earthen pans, of a very

porous quality, smeared over with butter on the inside, are

placed on it. In the evening, water is poured into these pans,

and ice from one to two inches in thickness, is found in them,

the ensuing morning.”

346 REFRIGERATION.

base the temperature \vas intensely high, their

temperature at which point is found gradually

to sink towards the summit, the whole of

those mountains are constantly coated and

covered with ice and snow.* The actual exexistence

of ice and of snow, in those regions,

decidedly proves that the solar rays are not

ignious rays, and that the sun is not, as Sir I.

Newton supposed it to be, a globe of fire. The

effects which ice and snow produce on other

bodies, are as definite and positive, as those

which are produced by fire ; the power of fire

to produce the sensation of warmth is not more

manifest, than of ice to excite the sensation of

cold; the one of expanding bodies, the other of

contracting them.

Instead of ice subsisting as the negative of

jfire, or cold the negative of heat, I consider that

the former is as positive as the latter, as

positive and separate, as the attributes of those

bodies which excite the sensations of sweetness

and of bitterness of odor and of sound.

I shall not stop, at present, to examine the

means by which the process of refrigeration is

accelerated and retarded^ or to investigate the

nature of those causes, by the operation of

which it is accomplished, by which the liquid

and aqueous particles, after being converted

from a liquid to ‘a gaseous form, and raised from

* Vide page 153.

REFRIGERATION. 347

the plain surface to the highest points of elevation

in the firmament, are afterwards resolved

to a liquid state, and ultimately made to

assume the consolidated form of ice and of

snow ; the effects of which, on the whole face

of creation, are known to the most superficial

observer. I shall, proceed, in the next chapter,

to explore the nature and cause of fire,

of that matter distinguished from every other

species by the sensation of heat which it excites,

in animated beings in general, and by the

expansion which it causes to common matter

in particular.

CHAPTER XVIIL

ON CALORIFICATION.

SECTION I.

On the Source from whence Fire is derived, and

the Means by which it is generated.

THE free and ready admission of the solar

rays in bodies, both diaphonous and opaque,

will be readily understood, after the description

which I have given of the subtlety of their

nature, and the power of motion which they

inherently possess. While they subsist in their

pure and elementary state, there is every rea*

son to believe, that they neither excite in animated

beings the sensation of illumination in

general, nor of heat or cold in particular ;

they are, in fact, destitute of all the attributes,

by which the identity of color or of

temperature is characterised : they produce,

on the common matter into which they may

have been admitted, none of the phenomena of

ignition or of cumbustion ; they subsist in those

bodies, in what may be called a latent and elementary

state, and are altogether invisible and

CALORIFICATION. 349

insensible. While the solar rays subsist in this

pure and elementary condition, they are as

different from what they are in a state of combination,

as the attributes of different compounds

are different from the elementary parts

out of which they were formed, as different as

the neutral salt is different from the acid and

the alkali, as ice is different from water, as

color from light, and as figure itself from extension

simply: insomuch, – that the definition

that would apply to the accident, would be altogether

irrelevant and improper for the element.

It is in manifest contradiction of this

truth, that the doctrine of latent heat, as

invented by Dr. BLACK, and as it is handed

down to us at this day is founded. According

to this hypothesis, fire, or the matter of

heat, as it is called, is supposed capable of

existing in two separate states ; in the one, it

excites the sensation of heat to animated beings

in general, and causes expansion to take place

in common matter in particular. In the othef

state, it neither excites sensation nor produces

expansion; in the former, it subsists simple

and elementary, in the latter, it is united and

neutralised (as it were) with th bodies in

which it is involved ; insomuch, that whenever

combustion, or the evolution of fire, takes

place, it is supposed to arise from the decomposition

which pure fire has undergone, that

CALORIFICATION.

being loosened from its confinement, it then

produces the various phenomena of sensation

and of illumination, of expansion and of combustion.

The former state is known by the

appellation of sensible heat, the latter of latent

heat. If the doctrine, however, of latent fire

were admitted (the term latent heat, as it mistakes

the sensation for the body which excites

it, appears to me a most objectionable one,)

we should be driven to the absurdity of having

two different definitions for one and the same

substance. A definition of fire in a sensible,

and another in a latent state : we should in the

one, define fire to be a substance which excites

the sensation of heat or warmth in animated beings

in general, and produces expansion in common

matter in particular ; in the other, ih&tjire

is a substance which neither excites sensation nor

expansion. This is both contradictory and absurd.

I shall, therefore, proceed to examine

the sources from whence fire, caloric, or sensible

heat is derived, and the means by which

it is produced.

If we search for the sources from whence fire

is derived, it will appear that it does not form

any part ‘of the essential attributes belonging

either to the resistance of solid, or the mobility

of liquid matter: neither are there any

grounds for supposing that the different rays of

light, which flow from the different parts of the

CALORIFICATION. 351

planetary system, are ignious or calorific rays.

The lunar rays have been collected and condensed

through different spectra ; although the

illumination, in consequence produced, was

more splendid and brilliant than the brightest

flame of the best candle, no sensible increase

of temperature was occasioned from them ; the

intense degree of cold, indeed, which frequently

prevails during the winter season, in different

countries, although illuminated by the rays of

the moon, decidedly prove that those rays are

not essentially hot. The observations which

have been made with respect to them, during

the winter season, more especially apply to the

solar rays at all seasons. Such is the extreme

state of refrigeration which every substance un^

dergoes, when it is exposed to their influence,

at the highest points of elevation, that the most

common observer will be led to conclude, that

the solar rays are not calorific rays, nor the sun

itselfa globe offire. It is very true, that the solar

rays have been examined by Dr. HERSCHELL,

and by other philosophers ; these experiments

satisfactorily prove, that the different colorific

rays have different degrees of temperature;

they, however, prove nothing with respect to

the temperature of pure light ; the colorific rays

which were separated from the colorless,

manifested all the phenomena of color and

temperature; the colorless, on the contrary.

352 CALORIFICATION.

were altogether insensible and invisible, while

they subsisted in their elementary and individual

state ;. it was not until they had united

with the muriate of silver, that it turned to a

black color, and temperature was produced.

While the attributes of pure light, therefor^,

enable us to understand its actual existence, in

different bodies, without either exciting sensation

or expansion, they lead to an explanation of the

various changes which different bodies are found

to undergo, in consequence of their union and

combination with it, by means of which the

various phenomena of color and temperature

are produced.

All the facts which we possess, go to prove,

that the solar rays not only remain in different

bodies in a latent state ; but that they pass

through particular bodies without uniting with

them ; they pass through snow, without melting

it, they pass through glass, without any

sensible increase of temperature. It may, indeed,

be observed in a general way, that the

solar rays pass through transparent bodies,

without being either arrested by them, or uniting

with them in any great degree. It, on. the

contrary, appears that the color of a body has

a considerable influence on them; insomuch,

that if bodies of different -colors, placed contir

guous to each other, are exposed to the solar

rays, the different changes which take place on

CALORIFICATION. 353

the temperature of each are obvious and direct.

This fact was proved and established by a long

series of experiments, first began by Dr. Hook,,

continued and varied by Drs. Franklin and

Priestley, by Mr. Cavallo, Mr. Davy, Dr.

Herschell, Sir Harry Inglefield, cum multis

aliis.

  1. Dr. FRANKLIN placed upon pure snow,

pieces of cloth of different colors, viz. white,

red, blue, and black, and exposed them to the

solar rays : he found that the pieces of cloth

sunk in the snow with different degrees of rapidity,

in proportion to the darkness or light*

ness in the color of the cloth; and that this

sinking of the cloth in the snow was caused

by the heat produced upon the cloth, and

thence imparted to the snow, which melted

in consequence.

  1. Mr. CAVALLO painted the bulbs of different

thermometers, not only with the different pris-*

matic colors, but black and white also, and

exposed them all, with respect to the rays of

the sun, in the same relative situations * he invariably

found, that the mercury in the thermometer,

whose bulb was either unpainted,

or painted white> was lower than in any of

the others* the mercury rising, in a regular

and progressive ratio, from these to the one

which was painted black, which was the highest

of the whole.

A A

354 CALORIFICATION.

  1. Mr. Davy varied Mr. Cavallo’s experiments

; the result, however, was found to be

uniformly the same. He took six pieces of

copper, of equal dimensions, the upper surfaces

of which he painted white yellow red

green blue and black : the opposite, or

dark side, he smeared over with lard, or cerate,

which he previously ascertained to melt when

heated to the degree of 76* of Fahr.: he placed

them in such a manner, as that the painted surface

only.was exposed to the rays of the sun

he invariably found, that the cerate attached to

the white bulb, was the longest time in melting,

and that the rapidity of the liquifaction

gradually increased, from the yellow to the

red, from the red to the green, from the green

to the blue and black.

Dr. HERSCHELL made experiments of a similar

nature, with the same result ; he was led

to perform them, in consequence of the necessity

he was under, at the time he was making

observations on the sun, by means of telescopes,

of making use of colored glasses, to prevent

the ardor of the rays from injuring his

eyes. He found, that when the glasses were

of a color, so deep, or dark, as to interrupt

the light, they very soon cracked and broke

in pieces. This circumstance induced him to

examine the heating power of the different colored

rays ; for which purpose, he made each of

CALORIFICATION, 355

them, in its turn, fall upon the bulb of a thermometer,

near which two others were placed to

serve as standards : the number of degrees,

which a thermometer, exposed to the colored

ray, rose above the other two, indicated the

heating power of that ray, he found that the

thermometer, which was either naked, or

whitened with paint, was lower than the one

which was blackened and that the white

thermometer, wrhen exposed to the red ray,

rose from 55 to 58-3 degrees* The black thermometer,

exposed to the same ray, rose from

58 to 61. The same thermometer, exposed to

the dark ray, rose in a greater proportion;

while the former scarcely rose one half degree,

the latter rose from 59 to 64. It is not surprising

that Dr. Herschell should express his

astonishment at finding that the illuminating

and heating power of the rays, follow such different

laws. According to the present doctrine

of fire, this difference is altogether inexplicable;

but according to the principles which

I have endeavoured to develope, they are the

effect naturally flowing from cause. We

find the colored, and, consequently, the combined

rays of the sun produce heat ; they produce

heat because they are combined, and they

are combined, because they are found to excite

the sensation of heat. The degree of heat these

rays are found to excite, will always depend on

AA 2

356 CALORIFICATION.

the intimacy of the combination, and the nature

of the color will arise out of the peculiarity iu

the arrangement of the particles of the matter

with which the union is effected. The purest

rays, therefore, which subsist in a most elementary

and nilcombined state, as we have seen

before, are destitute of fire, and of color.

When the solar rays pass through water

which is pure, or that which is colored, the

same difference in the temperature takes place.

At a time when the mercury of a thermometer

was at 61 in the air ; two other thermometers

were plunged into the clear, and into the colored

fluids ; while the former in fifteen minutes

only, rose to 64, the latter got up to 76.

If the quality of the base, on which the solar

rays fall, produces such a difference in the

degree of temperature, is it not, I would ask,

legitimate to conclude, that the cause of the

temperature itself which is produced, is the

result of the chemical union, which has taken

place between the one and the other ; that as

chemical affinity, or elective attraction, altogether

depends on the contrariety which exists

in the nature of the different parts, out of which

compounds are formed, so the intensity of the

temperature which is generated, will depend

on the contrariety which exists between the

purity of the solar rays, and the quality of the

base, with which they have combined.

CALORIFICATION. 357

The truth of this conclusion, is rendered

more apparent, when we reflect on the means

by which fire is factitiously and spontaneously

produced, while the union which takes place

between the solar rays and water is the causes

of which gasification is the effect, the union

of the solar rays with opake matter, on the

contrary, is the cause of combustion. When

the solar rays are brought to a focal point in

pure water, they produce in it, a slight increase

in its temperature ; if a piece of wood,

however, be immersed in it, the difference is

obvious and striking; under circumstances

such as these, the wood has been actually

burnt and charred, and a great increase in the

temperature of the water produced. Although

the concentration of a lens, enables us to collect,

and to condense, an immense mass of rays, to

one point, so as to have the whole accumulation

within a very small compass; if that

point be in the air, no sensible effect is

produced; if, on the contrary, a solid substance

be (exposed to its influence, fire the most

vivid and intense is the direct and immediate

consequence, and all the phenomena of ignition

and of combustion immediately follow.

As the materials of which fire is composed,

are all referable to light and opake

matter, so the means by which it is produced,

are either chemical or mechanical, separately,

358 CALORIFICATION.

or in conjunction. That this is the fact, will

appear, if the effects are examined, which are

produced by compression alone, in consequence

of mechanical power. If a volume of

air, enclosed in a syringe, be condensed, from a

large to a small compass, the generation of fire

is so great, as to be immediately rendered sensible,

by the increase of temperature, which is

felt through the sides of the syringe. The

power of friction, and of percussion, between

solid bodies, in the generation of fire, is familiar

to all ; by means such as these, a spark of

fire, and of color, may be evolved by the friction

together of two pieces of quartz, two

sticks may be ignited to a flame, a nail be

hammered redhot ; and the electric fire itself

can be excited near the surface of the earth, by

means of an electrical machine, as perfectly as

we often behold it produced in the upper regions

of the air. The consequences of this are

manifested by the fire, and .color, which are

generated and evolved. Although the electric

may form a distinct species from our common

culinary fire, it belongs to one and the same

genus, in its nature, and in its essence.

Like other species of fire, it produces co-

Jor, and excites heat, it dilates bodies,

it fuses metals, it kindles combustibles, as

they are called, and is most ardent in dry

CALORIFICATION. 359

weather. The means by which the electric

fire is generated on a machine, are evidently to

he referred to a mechanical cause ; by the

light, which is latent, in the atmosphere,

being forced by the motion and pressure of

the cylinder, to unite with the opake matter,

in the form of an amalgam.

From the mobility which exists in the particles

of which liquid and gaseous bodies, in

general, are composed, a more extended surface

between each presents itself; so that

wherever ignition takes place in them it not

only extends more widely, but is accomplished

more rapidly than in bodies of a more compact

nature ; instead of slow combustion, explosion

ensues.

The generation of fire takes place by the

chemical combination together of hydrogen

and oxygen gas ; hydrogen gas is perpetually

given out during the decomposition of

animal matter, and when there takes place a

chemical union of that gas with the oxygen

gas which the atmosphere contains, explosion

immediately ensues, manifesting the phenomena

of color, and of temperature, the

elastic power which these gases separately

possessed by combination become weakened

and lost ; insomuch, that the water which was

either suspended in them, or chemically com360

CALORIFICATION.

bined with them becomes deposited from them,

in the form of rain. The whole of this phenomenon,

is exactly similar to what takes place in

the upper regions of the air, by the effect of

lightning*

*

It has been owing to this ultimate effect, that chemists

have been led to conclude, that these airs are the elements

out of which water is constituted and formed ;^-that they

bear, in fact, the same relation to water, as cause does to

effect, that a whole does to a part. If this conclusion were

as true as it is false, if water were the effect produced, and

air the cause producing ; the consequence would be, that the

matter of the producing cause, (i. e. air,) must be sufficient in

bulk and quantity, to account for the whole quantity of the

effect produced, (i. e. the water.) I would then ask, whether

it is not prima facie, a violation of common sense to suppose,

that all the water which is kept suspended in the air, in the

form of atmosphere and clouds, all the water which flows in

rivers and lakes, and which exists to an unfathomable depth

in the ocean, can be the product of these airs. It might as

reasonably be supposed, that all the water in the ocean is

formed out of the rivulets and brooks, instead of the waters

of these being parts of which the ocean is the whole. That

the quantity of air is altogether insufficient to acconnt for all

the water which actually exists, is further proved by comparing

the relative densities of each, as ascertained by the

relative degrees of gravity in each. The relative gravity of

water to oxygen gas, is as 1 to 1,000; of water to hydrogen,

as 1 to 13,000 ; so that 1,000 cubic inches of the former, and

13,000 of the latter, by combination, produce one ounce of

water only ; not the superior density of the one, and the rarity

of the other, must be taken to the account, but the

extent and limitations of each also : although we cannot faCALORIFICATION.

361

If we examine the changes which those elements

have undergone, of which this new compound

is formed, their sensible properties will

be found totally different in their combined,

from what they were in their elementary state.

While therays of light proceed from theirsource

to boundless space, with the velocity of 200,000

miles in one second of time, the motion of the

calorific rays are limited and retarded, and

ultimately arrested, while the direction of the

motion of the one is from the perpendicular to

the base ; the motion of the other is rather directed

from the base to the perpendicular,*

thorn the depth, or calculate the quantity of water which

exists, we know, with tolerable accuracy, the limited extent of

the region of the air. We may, therefore, conclude, that the

one is totally unequal to account for the existence of the other.

That these airs did not exist originally, or antecedently, to

water, is proved from hence, that either one, or both of them,

are the produce of vegetable or animal action ; or from the

decomposition which living beings undergo, by the process of

putrefaction and decay. I do not mean to speak of the factitious

means by which they are prepared. I allude to the

common sources from whence they are actually and spontaneously

obtained. If these airs have their source from living

beings, if they are effects of which living matter is the cause,

it is impossible that they can be the sonree and the cause of

water, because water existed antecedently to cither the one,

or the other.

* If two bars of iron, of equal dimensions, are placed

through the same fire, the further extremity of the upper one,

302 CALORIFICATION.

The light loses its transparency, and becomes

thickened, from being colorless it becomes

variegated, from being destitute of

temperature, it acquires it to an extreme degree,

instead of permeating transparent and

diaphanous bodies, and remaining in them

latent and unaltered ; the matter of fire, on

the contrary, manifests its actuality and presence,

by the production of temperature like

streams of blood, that circulate through the

most minute vessels of a living system, it perwill

become redhot, much sooner than the further extremity

of the lower one. So little is the tendency downwards in the

motion of fire, that COUNT RUMFORD, was enabled to make

the upper surface of water to boil, at a time that a cake of ice,

which he had placed at the bottom of the vessel, remained

unaltered and frozen ; and the increased degrees of temperature,

at the top of a temple, and of a theatre, from what

exists at the bottom of it, must have been observed by all.

While fire, or the matter of heat, increases the bulk, it decreases

the weight of bodies, making them lighter than

before, although it is more opake, than the element of light,

it is, perhaps, the rarest and most subtile compound which

exists. If its density could be measured in the element of

light alone, it would gravitate and fall ; but being more elastic

than the atmospheric medium in which it is situated, it

overcomes the resistance of the air, and rises through it. It

is the case with smoke, in which a large proportion of fire is

involved ; it is found to rise faster in a dense, than in a rare

atmosphere ; and it sinks altogether in a rarified one. The

effect is rendered very visible under a receiver, in which any

substance may have been burnt the smoke ascends at first

CALORIFICATION. 363

meates and penetrates the pores of which the

most solid substance is composed, expanding

and devellating the whole into parts, and like

the baseless fabric of a vision leaves not a

wreck behind. It is, I may say, owing to the

warfare of opposite elements, uniting and fighting

together, that the different materials of

which fire is constituted, lose the identity,

which each separately possessed. So far,

therefore, from lire being a simple, elementary

body, it is far more reasonable to suppose, that

it is one which is compounded and factitious

and that it bears the same relation to light and

opakc matter, as the prismatic colors to atmosphere

and light ; the opake matter, becoming

the pabulum to light; and light the pabulum

to opake matter, the result of which is the

generation of fire ; fire, therefore, neither inheres

in any part of the materials of which the

world is composed ; nor in the pure solar

rays, the immediate and proximate cause, appears

to consist in the chemical union and comfrom

the bottom to the top ; when the air, however, which the receiver

contains, becomes exhausted, the column ofsmoke is suspended,

and as it becomes heavier than the medium which it has

displaced, (at the same time that it has lost its elastic power,

from the fire which it contained,) it becomes heavy and sinks

to the bottom. Fire may, therefore, be considered heavy

with relation to the matter of light, but light with relation to

all other bodies.

364 CALORIFICATION.

bination, which has been accomplished between

both. Combustion is, in fact, an act of

solution, by the agency of which, the bonds

which hold together bodies the most compact,

are loosened and separated, by which they are

changed from H solid to a liquid state, and

finally dissipated in vapor.*

* LAVOISIER’S opinion of combustion is, that air contains

a quantity of the matter of tire, chemically combined with it;

that during combustion, the gravitating matter of air, combines

with the combustible body, and parts with its fire,

which appears as heat and light. He considers free caloric,

to be the portion which produces temperature ; and that

combined caloric, is that portion which is chemically combined

with the body, and cannot be abstracted from it by

chemical decomposition, and which is disengaged during combustion,

owing to the combustible body exerting a stronger

attraction for it, than the caloric does to the concrete oxygen.

He supposes, therefore, a combustible body to be one, which

has the property of decomposing oxygen gas, one for which

the oxygen has a stronger affinity, than it has to the matter of

heat; so that combustion is nothing more, according to

him, than the separation of oxygen from the matter of heat.

He is also of opinion, that air is compounded of the matter of

fire, With a substance which is its base ; when a substance

with which it has a greater affinity, is presented to this base,

the matter of fire becomes free, resumes its properties, and

appears with heat, flame, and light.

CALORIFICATION. 365

SECTION II.

(f,

*

%Poyr of Fire over Liquids and Gases.

Such is the power which fire absolutely possesses

over different bodies, whether they be

solid or liquid, that we know of very few, that

are capable of resisting its action, when it is

accumulated to an extreme degree. By exposure

to a certain degree of fire, it is probable

that most solids maybe converted into liquids;

and all liquids, by increasing the quantity of

fire, may be made to undergo the further

change from a fluid to a vaporific state. The

dilatation, which different bodies sustain by

the agency of fire, varies in a considerable degree

; neither does the degree of expansion

bear any certain proportion to the quantity of

fire which is introduced. Solids, for the most

part, have a greater power to resist its influence

than liquids, and liquids more than gases;

although the volume of water is somewhat

augmented, as its temperature increases from

the free2ing to the boiling point, the augmentation,

however^Js small, when compared to

what it has attained in its vaporific state*

If the properties of this vapor (of this new

366 CALORIFICATION.

compound) be examined, they will be found

to be totally different, from those of its

elementary parts ; instead of the fire radiating*

from a point, to an indefinite extent, its power

of motion becomes more limited and bounded,

in consequence of the resistance to which it is

exposed : and, instead of the water continuing

1

incompressible as before, it acquires an expansible

power, to a very great extent. At the

point of ebullition, the dilatation which it then

undergoes, suddenly increases in a greater degree,

than the augmentation of the fire could

be supposed capable of producing. Mr. GREGORY

very properly observes, that there is a

very considerable difference in the result of experiments,

performed with a view of determining

the ratio, between the densities of water,

and the vapor of water at the boiling point ;

while Mr. HENRY states it to be as 1728 to 1 ;

others have carried it as far as 2, and even 3,000

times its original bulk. However varied the proportion

may be, the fact is universally admitted,

the power which vapor possesses of pressing

upon surrounding bodies, and of overcoming

their resistance, is familiar to every one. The

celebrated Engineer, VAUBAN, has observed,

that while 140lbs. of gunpowder, can only explode

and overcome the resistance of 30,000

weight; 140 Ibs. of water, converted into vaCALORIFICATION.

367

por, will explode and blow up, a weight of

77,000 Ibs.*

Great as is the power which vapor possesses,

it is evidently to be referred to the agency of

the fire which it contains ; the water which

enters into its constitution, is of itself as incapable

of expanding, as it is of condensing ; no

force, however great, (as I have before had

occasion to notice) has been able to diminish

its volume : it, in fafct, is incompressible, and,

therefore, can suffer no compression ; when

water, therefore, is acted upon by light, or by fire,

and converted from a liquid to a gaseous, or vaporific

state, the substraction of the agent in the

process of evaporation, is always accompanied

by a loss of the attribute, which the water had

acquired, the vapor returns back from dryness

to moisture, from an elastic and expansible, to

an incompressible and an inelastic condition. Although

both vapor and gas belong to the same genus,

they form very different species. The conversion

ofwater into steam, by the agency of fire,

is of a very transient nature; whenever the matter

of heat is abstracted out of it, the water

returns from its vaporific, to its liquid state ;

whereas the gasification of water, by the agency

* No wonder then, that the ingenuity of man, should have

converted a power such as this, to the most useful purpose,

as is found in the steam engine.

368 CALORIFICATSON.

of the solar rays, not only preserves its gaseous

form, near the surface of the earth, but at the

highest point of elevation, and at all degrees of

temperature, whether high or low. It is this property

which particularly distinguishes gas from

vapor ; vapor by the reduction of temperature,

loses all the properties which it had obtained,

and returns to its liquid state; gas, on the

contrary, not only preserves its gaseous state

at all degrees of temperature, but of external

pressure also; while a cold decanter, introduced

into a hot room, will separate the water

from the gas/and collect it on its whole surface:

gas will not only remain unaltered by time,

but preserve its gaseous form under unequal

degrees of temperature, for an indefinite period.

The difference which exists in the property

of gas and vapor, clearly proves the difference

which exists in the nature of the agent, by

which the conversion of water into vapor, and

gas, had been accomplished : it manifests that

the power of the solar rays far exceeds the power

of caloric, or fire. Although the dilatation be

very considerable, which water undergoes when

it is converting from a liquid to a vaporific

state, it, nevertheless, bears no proportion

%to

its power of dilatation after it is actually

formed into vapor. From Mr. DALTON’S

experiments it appears, that however different

the chemical properties of different gases may

360

be, the expansibility is alike in all, and that

they all undergo, by the addition of the same

quantity of fire, the same relative increase in

their bulk. Mr. Dalton found that 100 parta

of air, by having its temperature raised from

65 to 212, expanded 132-5 parts, which gives aft

increase of bulk of 000,207, or ^ parts to 1.

Can it, I would ask, be supposed that this wonderful

increase of bulk can arise from the in*

creased pressure of the air upon it, and that

the removal of resistance is the cause from

whence this expansive power is derived? A

supposition, such as this, is a most erroneous

one ; the abstraction of any compressing force,

from any expansible body, does not impart to

it any expansible power. The expansible

power of air existed before the compressing

force was applied ;

it existed from the instant

that the gas was formed, and the substraction

of the compressing force, has the effect only of

enabling the expansible body to expand with

greater freedom than before.*

* 1 hope to be excused from reverting again to this subject.

If any quantity of gas be made under water, the surface

of which is not an inch above the vessel in which the gas is

received, the gas will possess the same degrees of expansible

power, as if it were made in the open air. It will, I know,

be said, that the whole incumbent weight of thfe atmosphere

still exists. I allow that the atmosphere exists, but I deny it

exerts the weight which is ascribed to it. I appeal to the

B B

$70 CALORIFICATION.

Ought it then, I would ask, to be considered

a matter of surprise, that the immediate union

of the pure solar rays with opaque matter,

should be capable of producing all the phenomena

of combustion, and that the uncombined

state of the solar rays, which fall on the most

lofty summit of the most lofty mountains, should

be accompanied by volcanic eruptions; whether

they be situated at the polar or meridional

regions of the world. At those elevated points,

the rarity and purity of the medium affords

neither abatement to the power, nor resistance

to the motion of the solar rays ; the union,

therefore, which takes place with the opaque

matter on which they fall, may be supposed to

be of the most active kind.

SECTION III.

The Cause and Nature of Earthquakes.

These principles will more especially explain

the cause of earthquakes, of those violent

shocks of nature which take place, that develate

and tear- asunder the bowels of the earth, extending

far and near, and involving whole

proofs which I have offered in support of my opinion, as well

as to the demonstrative proposition, that a body which acts

equally in evtry direction, cannot act particularly in any one

direction.

CALORIFICATION. 371

districts in devastation and ruin. They will

more especially take place in those situations

of the world, where bituminous and sulphurous

strata and other substances exist,

constituting the pabulum with which the matter

of light may unite and become ignited.

In many countries it cannot be otherwise

: sulphur is often found to subsist in

collected masses in a native form, and the

quantity of kali and of wood, furnished by the

decomposition of vegetables that have perished

and decayed all furnish ingredients for the

formation of inflammable powder : a certain

degree of heat alone is necessary to ignite such

a mass. When we reflect on the quantity of

fire and of air which is evolved during the

process of fermentation, we shall readily admit

the efficiency of the means to produce the end:

wherever the strata of the materials I have

mentioned, subsist in great abundance, and

continue to great extent, I see no impediment

to the production of inflammation, manifesting

the phenomena of heat and of color, of

expansion the effect of ignition, and the consequent

explosion of the incumbent parts, undermining

and springing the foundations of the

strongest habitations, and involving them all in

one general wreck.*

*

I recollect in my early infancy, that there was a laboring

gardener, who used to entertain the little children of the neigh-

B B 2

372 CALORIFICATION,

I shall briefly detail one of the earthquakes

‘which took place in Italy, in the year 1 793,

the particulars of which have been so ably

related by the late Sir WILLIAM HAMILTON.

From the month of January to the month of

May, the atmosphere was generally calm, and

the weather dry ; and for several days before

bourhood, by mixing together different materials, and after

inhuming them to a considerable depth, an explosion or artificial

earthquake was, after a given time, the consequence. In

the lectures that are delivered by Professor Davy, at the Royal

Institution, I find that he exhibited the very same phenomenon

: he exhibited the model of a mountain made of clay,

in which was inclosed a mixture of potassium, filings of iron,

and lime. On pouring water into a fissure of this little mole

hill, violent combustion ensued, flame, and smoke were vomited

out of the little crater; boiling hot lava ran over the

surface, and spread over the side of the mountain; the whole

of which formed a most accurate exhibition of a volcanic eruption.

This very curious experiment was observed by the great

babies in petticoats and in breeches, as it had been done by

the little ones before^ with astonishment and universal applause.

It is very probable, that it was exhibitions such as

these, that led Dr. Enfield to observe ” that the hardy perseverance,

and the rigorous exertions which are necessary to

form the character of a philosopher, are so contrary to that

effeminacy and frivolity which distinguish the present age, that

if it were not for the provisions made in our universities, and

other seminaries for the propagation of sound learning, it is

to be feared that the more abstruse and difficult branches of

science would be excluded from the modern sstem of eduCALORIFICATION.

373

the shock took place, the water in the wells had

considerably diminished, some requiring ropes

of great length to reach the water, and in others

the water totally disappearing. About eleven

o’clock at night, the 12th of June, 1793, Sir

William says, “atNaples, we were sensible of a

violent shock of an earthquake which lasted

nearly half a minute ; it was more particularly

felt by the inhabitants of mount Vesuvius, who

all agree that the shock was from the bottom

upwards, after which an undulatory motion

was felt arising from the east and spreading

towards the west, and which extended upwards

of 30 miles from Naples. On the 15th of June,

soon after ten at night, another shock was felt,

but neither so long nor so violent as the former

one ; at the same moment, a fountain of fire,

attended with a very black smoke, and a loud

report, was seen to issue and arise to a great

height from out the middle of the cone of Vesuvius.

Soon after, another of the same kind

broke out at some little distance lower down,

as I suppose, by the blowing up of a covered

channel full of red hot lava. Fresh fountains

of fire succeeded one another hastily, and all in

a direct line, tending for about a mile and a

half towards the town of Torre del Greco. 1

could count fifteen of these, although I believe

there were many more, but which were obscured

by the smoke : it seems probable that all

374 CALORIFICATION.

these fountains of fire from the exactness in the

line of their direction, proceeded from one and

the same long fissure, one mile and a half in

length down the flakes of the mountain, and

that the lava and other volcanic matter, forced

its way out of the widest parts of the crack

from many mountains and craters. This fiery

scene was accompanied by the most horrid

noise; it was as the mixture of the loudest

thunder with incessant report like that from a

numerous heavy cartillery, accompanied by a

continual hollow murmur like that of the roaring

of the ocean during a most violent storm.

And added to this was another blazing noise

like that of the going up of a large flight of sky

rockets, similar to that which is produced by

the enormous bellows of the furnace of the

iron Carron foundry in Scotland. All that

time, there was not the smallest appearance of

fire or of smoke from the crater on mount Vesuvius.

But the black smoke and ashes issuing

continually from so many new mouths and

craters, formed an enormous and dense body

of clouds over the whole mountain, replete with

the electric fluid, making flashes of a zig-zag

form, called here Ferilli. Out of these gigantic

and volcanic clouds, I have seen balls of fire

issue and burst in the air: on the 16th, the

crater of Vesuvius showed signs of being on fire,

by some black smoke issuing out of it. At dayCALORIFICATION.’

375

break, issued another smoke tinged with red, increasing

until the whole was involved in fire,

in lightning, and in smoke. The ashes that fell

were wet, and to the taste very salt and pungent,

and contained many saline particles.

The breadth of the lava which fell into the sea

>

and which has now formed a new promontory,

after having destroyed the greatest part of the

town of Torre del Greco, is 1204 English feet,

its height above the sea 12 feet, and as many

under, 24 feet altogether ; and it extends into

the sea 626. I observed the sea water was

boiling as in a caldron where it formed the foot

of the new promontory, and smoked at 100

yards distance. I then put my hand into the

water, which was literally scalded, and the pitch

from the bottom of the boat was melting fast,

and floating on the surface of the sea ; a number

of boiled fish were afterwards found floating

on the surface of the water.” The horrid chasm

which Sir William found to exist two miles,

formed vallies 200 feet deep, and half a mile

wide ; and where the fountain of fiery matter

existed during the eruption it formed littlemoun

tains with deep craters. And he is of opinion

that 10,000 men, in as many years, could not

have altered the face of Vesuvius so much

was effected by this concussion, in the space of

four hours. He went on the top of some of the

most considerable of the new formed moun376

CALORIFICATION.

tains, and looked into their craters in circumference

about half a mile. Although the inte*

rior perpendicular height of many of them did

not exceed 200 feet, the depth of their inverted

cone within was at least 600, giving out sulphuric

vapours ; and in all there were depositions

of salt and sulphur. The ashes were

carried as far as Tarento, a distance of 25Q

miles, and as far as Lucca, which is still further

; and the Bishop of J)erry, in a letter

from Sienna in the Tuscan state, about 18 hours

after the commencement of the eruption, said,

that in the midst of a most violent thunder

gtorm, about a dozen stones of various weights

and sizes, fell at the feet of different persons ; the

stones of a quality, not found in any part of the

Siennese territory, one of which weighed 5lb. *

The torrents of water mixed with ashes and

mud that rushed from the summit of Vesuvius

to the adjacent countries carried with them

* It has become a question whether these stones have been

generated in this ignious mass of clouds, which produced such

universal thunder, or whether they were thrown from Vesuvius.

Is it not probable, that the different meteorological

stones which have fallen at different times, have arisen from

the same sources? and not from the disruption of mountains

in the moon, as the celebrated da Place, and others, have fancied.

It is, however, a curious circumstance, that these stones

are all combined of the same materials ; they are composed of

iron and of nickle, with a certain proportion of silex arid of

magnesia, a small portion of chrone and iron pyrites.

CALORIFICATION. 377

desolation and ruin. Sir W. H, is decidedly

of opinion that these floods were occasioned by

the sudden dissolution of watery clouds, the

air having been too much rarified to support

them. They, therefore, burst ; the water falling

from the air in streams, which, uniting with

fire, with ashes of a bituminous and oily quality,

and accumulating in pools to a great

height, at length forced its way into new

channels, and came down in torrents in countries

where it was least expected : composed of

scoriae, ashes, and stones, mixed with trees

that had been torn up by the roots : some of

the torrents were of the height of 10 to 40 feet,

carrying houses, walls, trees, and as it is said,

not less than 4000 sheep, with teams of oxen,

&c. &c.”

Whoever reads the sad history of the different

earthquakes, by which different parts of

the world have been visited, will be struck with

horror and with amazement: he will read of

large and populous cities, convulsed and shook

from their very foundations, buried and immured

to a considerable depth, with all their inhabitants,

the wrecks and ruins of which are

visible at this time. In the 17th year of the

Christian sera, under the emperor Tjberius,

Strabo relates that a dreadful earthquake took

place, in which twelve cities of Asia Minor

were destroyed in one night ; and it appears

378 CALORIFICATION.

from the remote situation of some of them, that

they must have occupied a circuit of 300 miles

in diameter. It is related by Gibbon, on the

authority of Ammianus, that the greatest part

of the Roman world was shaken by an earthquake,

that the shores of the Mediterranean

were left dry by the sudden retreat of the sea,

that great quantities of fish were caught by

the hand, and large vessels were stranded on

the mud. This state ofdesiccation was of short

duration ; the tide soon returned with the

weight of an immense and irresistible deluge ;

the effects of which were particularly felt from

the Sicilian to the Egyptian shores. Large

boats were transported on the roofs of houses,

multitudes of people were swept away by the

reflux of the water, and it is supposed that not

less than 50,000 persons lost their lives in the

inundation. Although there are few countries

extant, that have escaped these dreadful shocks,

there are many countries situated in the same

latitude, that seem particularly exposed^ to

them. The island of Jamaica has suffered and

been ravaged by them more than any of the

West India islands. In the year 1692, niuetenths

of the town of Port Royal, the metropolis

of that island, were destroyed by an earthquake,

in less than the short space of two

minutes : the houses sunk 30 or 40 fathoms

deep, the earth opened and swallowed up numCALORIFICATION.

379

bers of people, many of whom rose up in other

streets, as well as in the middle of the harbour.

One of the most destructive and extensive

earthquakes that is recorded in history, happened

in the year 1755, and as it proved more

particularly fatal to the city of Lisbon, which was

entirely destroyed by it, with 60,000 of its inhabitants,

it is generally known by the name of the

great earthquake of Lisbon. Although its violence

was more particularly felt in Portugal, it

extended not only over the whole peninsula, but

to Africa, and different parts of Europe ; covering

a tract of more than four millions of square

miles. The earthquake of 1782, which overwhelmed

the Neapolitan territory, destroyed

no less than 30,000 inhabitants, independently

of 6000 who died of disease, the natural consequence

of misery and alarm. The sad, but

interesting, detail of which has also been given

by the late Sir William Hamilton.

A variety of causes have been assigned for

these destructive effects by different philosophers,

and Dr. STUKELY, in particular, has

endeavoured to show that they were produced

by the electric fire, which tears up and rends in

pieces the bowels of the earth. That subterranean

fire is the proximate and immediate

cause of earthquakes, appears to be decidedly

proved by all the phenomena with which they

are accompanied. The fire not only forces

380 CALORIFICATION.

itself a passage through various fissures which

it makes, but converts a vast quantity of water

into vapor and steam ; by whose united aid,

the resistance of the incumbent mass of earth

is overcome, and a general overthrow produced,

attended with all the consequences which have

been detailed.

Some there are, who question the efficiency

in the means to produce the end ; and Di\

Stukely, in particular, supposes that the earthquake

in Asia Minor, which extended over a

circle of 300 miles in diameter, could not have

been produced by the explosion of the greatest

quantity of gunpowder that can be conceived ;

and he starts this objection for the purpose of

strengthening his favourite doctrine, of an elec-r

trie shock. According to my view of the subject,

both suppositions are perfectly compatible

; as the electric fire is a species belonging

to the same genus as fire in general, it is produced

by the same means, and produces the same

effect.

We have a multitude of facts to show that

the .solar rays, concentrated by means of a lens,

in an exhausted receiver, produce fire the most

intense, as well as on the summit of the most

lofty mountains : and it may be mentioned as

one, amongst other circumstances, which distinguishes

light from fire, that while we possess

the most ready means of concentrating to a

CALORIFICATION; 381

focus the solar rays, we have no such power

over the rays of fire ; the repelling power which

they manifest, eludes all attempts to their concentration

; wherever they exist, they become

the immediate cause of which the dilatation

of the surrounding parts are the effects ;

the effects which are produced bearing a certain

and definite proportion to the quantity and

intensity of the fire which is applied. It is very

probable, that the electric fire, in passing

through the earth, was the primary agent in the

ignition of the combustible materials, which

were involved within its bowels, and in accomplishing

the combination of the (latent) light

with them : the fatal and terrific effects of which

We have seen extended far and near.

Great and astonishing as the power must

Unquestionably be, by the agency of which

these awful and frightful effects were produced,

it is, nevertheless, very probable, that it falls

infinitely short of what it was at the beginning,

-at that memorable epoch, the moment of the

creation,- at that memorable epoch, when

the earth was without form ; that is, when

matter existed without figure, and when

void, and when darkness was on the face of

the deep,- of the deep, or of that immense

space between the waters below and the

heavens above, in which no air or atmosphere

existed to fill it, no light to illumi382

CALORIFICATION;

nate it, no fire to warm it, and in which nothing

subsisted but the omnipresence of the

Almighty, who ” moved with his spirit upon the

face of the waters.” When God said, Let there

be light, and there was light, it was not said,

let there be fire, let there be color, but it was

said, Let there be light ; at this eventful period,

a new order of things immediately arose, and

effects the most violent, it is to be supposed?

immediately followed ; although these effects

were produced through the instrumentality of

secondary causes, they emanated more immediately

from the energy of Almighty Power ;

and it is but reasonable to suppose, that those

effects were as infinitely greater, than any that

have since happened, as the power of God

transcends the power of man. If it be not

presumptuous to form a conjecture upon such

a subject, I should say that the union and combination

which immediately took place between

the light and the waters that were above the

surface of the earth, was followed by the conversion

of both into air ; that the action of the

light and air upon the opaque matter of which

the earth is composed, became the immediate

cause, of which fire was the direct and immediate

effect, the ultimate consequences of

which were felt far and near ; and that a general

disruption of the solid nucleus of the

earth, and a separation of the whole into two

CALORIFICATION. 383

separate parts, was thereby accomplished, with

the various subordinate divisions and separations

of those parts into smaller portions, as they

are found to exist in different islands, seas, &c.

that this shock was more particularly felt under

the line of the equator, where the solar rays,

from their vertical position, have the greatest

power; that by means such as these, two

great continents were formed ; the waters,

divided from the waters, and dry land appeared

; the whole fitted and adapted for the

habitation and residence of the infinite multitude

of animated beings, which were afterwards

created.

Whoever reflects on the effects which would

be produced on the whole planetary system, by

the intervention of the expansible bodies produced,

by the various meaons to which I have alluded,

will see the absolute necessity which exists,

that no part of them should ascend beyond

their proper bounds, but that means should exist,

by the operation of which they should be limited

and confined. Ifit were otherwise, if their

decomposition did not take place, there is every

reason to suppose that the whole mass of water,

of which the ocean is composed, would, in

the process of time, be evaporated, and converted

by the sun into a gaseous form ; the consequence

would not only be felt, by the state of

desiccation that would, long before this, have

384 CALORIFICATION.

Inken place on earth, but by the irregularity in

the motions of the whole of the planetary systeiti

that would inevitably have ensued* If the spheres

through which the different planets describe

their periodical revolutions, were rendered more

dense and resisting at different times, the regularity

of those motions would be perpetually disturbed,

and a total derangement of the whole

system of nature would follow. The providence

of God, therefore, by the supreme knowledge

of causes and of consequent effects, foreseeing

the disease, applies the cure; by the

agency of means, which not only preserve

harmony and order in the system of nature, but

which conduce to the preservation and support

of his creatures.

-CHAPTER XIX.

DECOMPOSITION OF ATMOSPHERIC

MATTER, ANP THE FORMATION OF

RAIN, ETC.

HOPING that I have been a fkilhful historian of

the phenomena which I have described, and

that I have succeeded in tracing, (as far as the

narrow span within which my abilities are confined

will admit,) those phenomena to their producing

causes ; it only remains that I should

point out the progressive changes which the at*

mosphere undergoes, when the parts, which

are converted from a liquid to a vaporific, and

gaseous state, are made to return back from a

gaseous to a vaporific, and, finally, to a liquid

one ; these causes may be principally referred

to combustion, to the absence of the solar

rays, to the changes of day and ofnight ; and

to the different seasons of the year. And finally,

to whatever cause by which the expansibility

of the atmosphere is weakened or destroyed.

This loss of expansibility which the air

c c

86 ATMOSPHERIC MATTER.

suffers by combustion is proved by the decomposition

of the water out of it. We have the fact

proved in a general way, constantly before our

eyes, by the depressions which the mercury of

the Eplanometer sustains in a storm, and its

elevation in a calm, in a wet and in a dry day ;

sinking, more especially in tropical climates,

where the periodical changes which take place

in the atmosphere, are more evident, and considerable,

than they are in lower latitudes, the

mercury sinking from the elevation of 31 to 27

inches; and in this country, from 30 2-10

to 28.

The reduction of the expansible force in the

atmosphere is observable at night, by the absence

of the solar rays, more especially in the

summer season, when we behold a large proportion

of the water which had been during the

day, absorbed and gasified, return during the

night from gas to vapor, from vapor to moisture,

or dew. It is owing to the decreased degrees

of expansibility in the atmosphere, in

consequence of its increasing dilatation from

the surface of the earth, to the more elevated

regions, that from being clear and transparent,

it is found to terminate in a turbid or

foggy state, known by the name of clouds ; so

that the transmutations which we often behold

clouds and fogs undergo, from dryness to

moisture from levity to weight from suspenATMOSPHERIC

MATTER. 387

sion and balance, to precipitation and fall, are

merely different stages and degrees of one and

the same process ; or, in other words, the state

of levity which the watery particles had ao

quired, while they subsisted in a gaseous state*

become progressively impaired, or lost ; they

become relatively heavier than the rare medium

in which they are situated ; they therefore obey

the laws of relative weight, and in their descent

through the air, they become compressed and

shaped in different forms, increasing in magnitude

as they approach the earth ; they fall on

the surface, and are known by the various ap

pellationsof rain, of hail> and of snow. These

spontaneous changes, which take place in the

atmosphere, may in a limited degree be iim^

tated by art, and are followed by the same

consequences. The expansibility of the atmospherical

air may be weakened by combustion,

as well as by being rarified and partly exhausted,

as in the air-pump ; such is the dilatation

which, the residuary air has in consequence

sustained, that its power of supporting the

aqueous particles becomes progressively and

proportionably weakened : after a few strokes

of the piston, a very sensible change in the

decomposition of the air becomes perceptible

; from being transparent and dry, it becomes

turbid and moist ; and when the exhaustion

is made as complete as it is st*sceptible of,

cc 2

388 ATMOSPHERIC MATTER.

a dewy moisture is observable trickling dowra

the internal surface of the receiver.

By the united combustion, in close vessels

of different gases, more especially of oxygen

and hydrogen gas, the same phenomena

take place : from being transparent and clear,

they become clouded and foggy ; from a state

of dryness, they become moist; such is the

degree of decomposition in them, which by the

combustion has been produced, that in the

space of about an hour, nearly the whole of the

water which the gases contain, is separated out

of them, and precipitated from them to the

bottom of the receiver.* This experiment,

which is neither more or less than a petty imitation

of the change which takes place in the

great laboratory of the atmosphere, by the

effect of lightning, has occasioned as much

clatter among experimentalists throughout the

world, as if they had discovered the philosophers’

stone ! !

* Under both circumstances fire is produced, manifested

by color and heat ; in both the water which was either suspended

and diffused, or actually gasified in these airs, becomes

decomposed and deposited out of them.

4Q98

CHAPTER XX.

-ON COMETS: o, THE MEANS BY WHICH TH

MATTER OF ONE SYSTEM IS PREVENTED

FROM INTERFERING WITH THE MATTER

OF ANOTHER.

THE different means which I have hitherto detailed,

by which the expansibility of the atmos*-

phere is limited and bounded, are parts only of

one general plan ; they are links belonging to a

chain of causes, which the GOD of Nature has

established, from the beginning of time, to the

end of it, by which not only the most minute

particles of matter belonging to our system,

but also that of the whole galaxy of heaven,

is regulated and governed. Obvious and

sufficient as those means appear to be, to prevent

the most dense and solid parts of this earth,

from ascending and interfering with the spheres

of other worlds, they are inadequate, and insufficient,

I apprehend, to confine, and to

bound within its proper limits, such portions of

the atmosphere as had been divested and stript

390 COMETS.

of their grosser particles. From the essential

property of expanding which these parts possess,

and from being situated in a medium

which affords to their expansible power little

or no resistance; it is a matter of necessity as

an effect immediately flowing from cause, that

the air, in its upper regions, should, in that

case, dilate to its utmost possible extent, and

diffuse itself to the uttermost regions of

space; so that all the materials on this earth,

which subserve to the . process of vaporisation,

would long before this period, have been dissipated

and elevated to distant worlds ; if there

did not exist means, by which those consequences

are prevented. We are, therefore,

driven to the necessity of searching for those

instruments, which a vigilant and protecting

Providence employs, and by which these deleterious

effects are effectually averted.

Without the existence of such instruments,

the whole economy of nature, would be subverted

and destroyed ; the planetary spheres

would be polluted, and penetrated by a constant

interchange of materials; they would

be rendered more dense, and more rare, at

different times. The planets, whose motions

are so regular and precise, would be either

accelerated, or retarded, in their course;

and neither their times, nor their revolutions,

could be anticipated, or ascertained.

COMETS. 391

It forms a part in the great scheme of Providence

in the physical government of the universe,

so long as it shall please God, that that

universe shall continue to exist, that those evils

shall not take place, they are prevented from

taking place not by the annihilation of matter,

but by the decomposition of it ; by bereaving

it of those powers of expanding, which it

had factitiously obtained, Whence (it may be

asked) are the means, through the agency of

which the end is obtained ? They are before the

eyes ofall, and are generally understood. It is

generally understood, because it is a general

fact, that the expansibility of air is weakened

and destroyed, by combustion ; whilst the base

of which the air was composed, becomes separated

from the light, the light is given out, as I

have before explained, in a calorific and colorific

state; and it may be presumed that by an extension

of the same process it becomes purified

from the dross with which it had combined,

and is returned back to the sun itself, from

whence it was derived.

It was from a course of investigation such as

this, that so long as eighteen years ago, I was led

to conclude, that COMETS were the instruments

which were employed to perform this beneficent

purpose ; that they were bodies which formed

the Jines of separation, and of demarkation*

between the planetary spheres : proclaiming

392 COMETS,

the voice of God, With a Tongue of Fire, lo the

matter of the earth, and of the whole planetary

system,

” Thus far shal t thou go, but no farther.”

With a reverential belief at that time, in the

whole truth of the Newtonian hypothesis, (unnatural

and artificial as it is,) I was, nevertheless,

led to conclude, and to publish, that

Comets, ivere bodies, which were destined to perform

the office, which I have above described ;

that they were destined to decompose through

the medium of combustion, whatever gaseous,

or atmospheric materials, had ascended

beyond their proper bounds ; that instead of

being limited, as I understood was the case, to

nine only, I was persuaded, that they were as

indefinite in point ofnumber> as they were in magnitude.

Instead ofdescribing regular orbits, that

they must be altogether irregular in their motions:

and finally, that instead of being permanent bodies,

and returning at stated periods, they were

transient and evanescent ; were finally dissipated

and decomposed, and no more seen. I, therefore,

ventured to affirm, that the uppermost limits

of our atmosphere, I teas persuaded, abounded

with them ; and that it was only a proof of the

insufficiency and imperfection of our instruments,

that they were so seldom discovered; that they

were in their nature fiery, like other meteors,

like lightning^ and other species offire, differing

tinly in quality, in consequence of the difference

COMETS. 393

fin the subtilty and nature ofthe materials ofwhich

they were composed, and that there were sublunary

Comets ; that iftlwre were Comets amongst tJie

higher planets, it thpetv some light on the nature

of the matter of which those planets were composed,

as it shewed, that they possessed an atmosphere

like our own, of a combustible nature ;

that it was probable their atmosphere was infinitely

rarer and purer ; and, consequently, that

the Comets subservient to the preservation of

ihe purity of their spheres, must move infinitely

more rapidly, and the lustre which they displayed

must be infinitely more brilliant, than those of a

sublunary nature.

Destitute of facts, by which those conclusions

were founded, they could only be considered

as unsupported assumptions from which

I had formed an hypothesis; I reasoned from the

necessity of the case, and not from any astronomical

knowledge which I possessed ; the late

Mr. GEORGE ADAMS, who was a good practical

astronomer, told me, in a conversation which I

had with him on physical subjects, that he had

been much struck with the deductions which I

had made, respecting the nature of Comets ;

for although it seemed as if I thought that nine

only existed, he could assure me, there were

many more ; and that M. MESSIER in particular,

of Paris, was nicnamed the Comet finder, in

consequence of the number of Comets which h<*

394 COMETS.

pretended to have discovered. Six months

after this, DI-.HERSCHELL published a paper in

the Philosophical Transactions, which tended,

in a great measure, to confirm, by facts, the

deductions which, from hypothesis?, I had made.

Of those bodies which I was ignorantly taught

were limited by astronomers to nine, but

which J ventured to assert very generally

existed in the upper regions, Dr. Herschell

says,

” Many of the operations of nature

are carried on in her great laboratory, in a

manner which we cannot comprehend ; but

now and then we see some of the tools, with

which she is at work. We need not wonder

that their construction should be so singular,

as to induce us to confess our ignorance of

the method of employing them ; but we may be

assured, that they are not a mere lusus naturce.

I allude (the Doctor goes on to say) to the great

number of small telescopic Comets, that have

been observed ; and to the far greater number

still that are, probably, much too small to be

noticed by our most diligent searchers after

them. Those six, for instance, which my sister

has discovered, I can, from examination, affirm,

had not the least appearance of anjr solid

nucleus, and seemed to be mere collections of

vapors, condensed about a centre. Five more,

that I have observed also,were nearly of the same

nature. This throws a mystery over their desCOMETS.

M 395

filiation, which seems to place them in the allegorical

view of tools, probably designed for

some salutary purposes to be wrought by them;

and whether the restoration of what is lost to

the sun, by the emission of light, the possibility

of which we have been mentioning above,

may not be one of the purposes, I shall not presume

to determine.”

I respect Dr. Herschell too much to accuse

him of plagiarism. It is, however, a little extraordinary,

that this paper should have been

presented to the Royal Society, a few months

only, after my book was published : and that in

this paper the Doctor ascribed to lightning, meteors

and cornets, the very use which I had done

before : that I should assert the necessityof their

existence; and that the Doctor should afterwards

declare, that he saw them, that they were

composed of the same kind of matter as I had

asserted, and that they were designed for the

same use. Without wishing even to suspect

that Dr. Herschell had seen my book, I think

it just to say, that the truth of my hypothesis

is strengthened by Dr. Herschell’s opinion,

and confirmed by his discoveries.

Reasoning, as I did, from universals, it became

a matter of necessity for me to inquire

how far the particular facts, justified the universal

conclusion. I, therefore, consulted the

various histories which have been given by dif396

COMETS.

ferent astronomers, of the different Comets that

have made their appearances at different times;

and from their testimony it appears, that neither

their revolutions, nor the periods of their return,

have ever been ascertained. If the motions of

Comets were regulated and governed by the

same laws which regulate and govern the planetary

system in general, the expectation of those

who have anxiously looked for the periodical return

of individual Comets, would not have been

disappointed; neither would the system of the

universe continue to exist, without some of the

parts sustaining violent and dreadful shocks,

from the violent appulse which those parts would

have sustained from the immediate contact

between them and Comets. The Comet which

has caused the greatest alarm to the inhabitants

of the earth, and been supposed to threaten it

with a visit, was the one of 1680. Dr. HALLEY,

by calculation found, that Nov. 11, 1680, at

1 h. 6m. P. M. it was not above one semidiameter

from the earth ; and had the earth, it is

said, been at that time in the part of her orbit

nearest to the node of the Comet through

which it passed, their mutual gravitation must

have caused a change in the plane of the orbit

of the earth, and in the length of our year :

and Dr. Halley adds, that if so large a body,

with a motion so rapid, as that of this Comet

nearest its perihilion, were to strike against our

COMETS.

globe, (a thing he conceived by no means impossible,)

the shock would have been so great,

as to have reduced this beautiful frame to itsoriginal

state of chaos ! M*

The Comet which was observed by APIAN,

In 1531, which KEPLER described, in 1607,

and which Dr. HALLEY supposes he observed

in 1682, and predicted would return about the

5th of April, 1758-9, is the only instance on

which the expected returns of Comets can be

justified. It is very true, that Dec. 14, 1758, a

Comet did actually appear. When we reflect,

however, on the multitude of those erratic bodies

which have been since discovered, it is no

wonder, that in the anxious expectation of the

fulfilment of the prediction ; when all the astronomers

were exploring every point in the

heavens, another Comet should have been

discovered ; and that this new Comet should

be supposed to be the same identical one that

had appeared 150 years before. The Comet,

however, of 1 770, whose period was supposed

to be five years seven months, has never since

appeared.

* How vain are those, fears, how fanciful those conjectures

1 From the history of Comets which we possess, it

appears decidedly to be proved, that instead of describing

complete revolutions, they are consumed and dissipated, long

before any one revolution is completed ; and, consequently,

that their return can neither be anticipated, or ascertained.

398 COMETS.

DE LA HIRE, and other astronomers, are of

opinion, that Comets never return. CASSINI,

and others, think it probable that they do ;

but NEWTON, HALLEY, FLAMSTEAD, and the

generality of the English astronomers, bigotted

and rivetted to their own system, are persuaded

that they have their regular periods,

although they are not so well ascertained, as

those of the planets. De la Hire, and Cassini,

observed a Comet in 1698, which they supposed,

from the velocity of the motion, and the

path which it described, to be the same as was

seen in 1 652 ;

its period appeared to have been

43 months ; and the number of revolutions from

1652, to 1698, they supposed to have been 14.

It is, however, very justly observed, that in an

age wherein the heavens are so narrowly

watched, it is hard to beHeve, that a Comet

such as this, should make, unperceived, 14

revolutions ; more especially as a Comet of that

description, might appear visible above a

month together. The Comet of 1702, viewed

by Cassini, and which he concluded to have

been the one seen in 1668, giving it a period of

36 years, has never again appeared, more than

a variety of others that might be mentioned.

Dr. Halley suspected that the Comet observed

by Apian, in 1532, was the same Comet as

had been observed by Hevelius, in 1661 : if

COMETS. 399

that had been the case, it ought to have returned

in 1789, or 1790, which it never did.

From the earliest periods, a variety of Comets

have appeared, that were neither anticipated

nor expected ; and whose motions and appearances

have born neither analogy nor resemblance

to the history which has been given of

those of former times. The history of the Comet

described by Hevelius, in 1661, perhaps,

conveys the most precise idea of the change

which it is presumed Comets undergo. Its

body was of a yellowish color, very bright and

conspicuous, but without any glittering light ;

in the middle was a dense, ruddy nucleus, almost

equal in size to Jupiter, encompassed with

a much fainter, thin matter : Feb. 5, its head

was somewhat bigger, but its light more dusky,

than the rest of the stars ; here the nucleus

appeared divided into several parts. Feb. 6,

the disk lessened, the nuclei still existed, though

less than before ; one of them on the lower part

of the disk, much denser and brighter than the

rest ; its body round, and representing a very

lucid little star ; the nuclei still encompassed

with another kind of matter. Feb. 10, the

head somewhat more obscure, the nuclei more

confined, but brighter at top than at bottom.

Feb. 13, its head diminished, both in magnitude

and brightness. March 2, its roundness

a little impaired, its edges lacerated. March

400 COMETS.

g8, very pale, and exceeding thin ; its matter

more dispersed, and no distinct nucleus at

all appearing; and I shall only revert to*

the Comets alluded to before, which Dr.

Herschell discovered^ and which he was in-*

timately persuaded to be mere collections

of vapors, condensed about a centre, without

any nucleus whatever ; to show the probability

which exists, that Comets are nothing more than

atmopheric matter, in a state of combustion.

The rapidity and intensity of the combustion

which is thus going on in Comets, may, in some

degree, be estimated from the colorific, and calorific

rays, which issue from them. Two

Comets described by JUSTIN, lib. 37, according

to his account,

” shined so bright, that the

whole heaven seemed to be on fire, and by their

greatness filled up a fourth part of the heavens,

and by their splendor exceeded that of the

sun ; and it is affirmed, with regard to the

Comet of 1401, that the sun being got below

the horizon, there appeared in the west,

a bright and shining Comet, sending out a

tail, upward, in splendor like a flame of fire,

and in a form like a spear, darting its rays

from west to east ; by the lustre of its own rays,

it enlightened ail the borders of the earth, not

permitting the other stars to show their lights,

or the shades of night to darken the air, because

its light exceeded that of the others, and

COMETS. 40 T

extended itself to the upper part of the heavens,

flaming.* Exaggerated as these descriptions

may seem, they were almost equalled by the

appearances of the great Comet of the year 1680.

With all the phenomena which belong to

Comets, it appears that they are bodies consisting

of materials in a state of violent combustion,

and that they are not what Sir I.

NEWTON supposed them to be,

solid, compact,

and fixed, and durable bodies, Mke the

bodies of the planets ;” for he goes oa to say,

” If they were nothing else but vapors^ or the

exhalations of the earth of the sun, and the

other planets : this Comet, in its passage by

the neighbourhood of the sun, would have been

immediately dissipated;” for Sir Isaac assumed,

that the heat of the sun, is as the density of its

rays, that is reciprocally as the square of the

distances of the place from the sun. Therefore,

since on Dec. 8, when the Comet was in its perihelion,

the distance thereof from the centre

of the sun, was to the distance of the earth

from the same, as about 6 to 1000, the sun’s heat

on the Comet, was at that time, to the heat of

the summer’s sun with us, as 1,000,000 to 36;

or as 2.8,000 to 1. But the heat of boiling water

is about three times greater than the heat

which (Jry earth acquires from the summer

* His. Byz. Due Mich Nepot.

D D

402 COMETS.

sun, Ihave tried; and the heat ofredhot iron, (if

my conjecture is right,) is 3 or 4 times greater

than the heat of boiling water. And, therefore,

the heat which dry earth, on the Comet, while in

its perihelion, might have concord from the rays

of the sun, was about 2000 times greater than the

heat of redhot iron. But by so fierce a heat,

vapors and exhalations, and every volatile matter,

must have been consumed and dissipated.

This Comet, therefore, must have conceived

an immense heat from the sun, and retained

that heat for an exceeding long time ; for a

globe of iron, of an inch in diameter, exposed

redhot to the open air, will scarcely lose all its

heat in an hour’s time; but a greater globe

would retain its heat longer, in the proportion

of its diameter, because the surface (in proportion

to which it is cooled by the contact of the

ambient air,) is in that proportion less, in respect

of the quanity of the included hot matter ;

and, therefore, a globe of redhot iron, equal to

our earth, that is, about 40,000,000 feet in diameter,

would scarcely cool in an equal number

of days, or in above 50,000 years.”*

So far, however, from subscribing to the

opinions that were entertained by Sir Isaac

Newton, that Comets are compact and solid,

fixt and durable bodies, like what he

supposes the planets to be ; I conceive that

they are composed of the rarest materials

*Davis’sTranslation of Sir I.Newton’s Principia, vol. 2. p. 285*

COMETS. 403

possible ; instead of deriving their fire and

splendor immediately from the sun, I conceive

that the fire and splendor which they display,

are effects only which are produced by the

union which has taken place, between the atmospheric

materials of which they are composed,

and the solar rays, with which they

have combined, that those pure rays ; being

destitute of fire altogether, could not convey

into the bodies of the Comets, any quantity

whatever of fire into them ; and, consequently,

that the various calculations that have been

made respecting their motion, and situations,

from the nature of the materials of which it is

supposed they consist, are altogether erroneous

and fallacious ; as erroneous and fallacious

as the supposed limits which have been

given to the elevation to which it is conjectured

our atmosphere extends. I conceive it as impossible

to measure the extent of it by means

of the barometers which are employed, as it is

for the barrow-boy in the streets, who sells

filberts by the pound, to measure in his scales,

the relative densities and weights of the planets

Jupiter and Saturn.

In order to bring my ideas, respecting

the nature of fire, to a close, I shall take

leave to observe, that I conceive the sun to

be neither hot nor cold, but to be constituted

of light only ; that the rays which perpetually

emanate from the sun as their source^

304 COMETS.

constitute the purest and most active species of

matter which exists, or of which we have any

knowledge ; that as they proceed from the

sun, they are perpetually combining with the

opake and atmospheric matter with which they

come in contact, producing the various phenomena

of Comets and meteors, lightning, culinary

and atmospheric heat. That it is by the

chemical union of this matter of light with

atmospheric matter, that heat, or fire, is first generated

; that this pure matter of light, or solar

rays, I conceive, constitute the caloric of the

present chemists ; that it is by the combination

of this light, or caloric, as they call it, not by the

decomposition of it, that sensible heat, or fire, is

produced, possessing properties in its combined

state, very different from what it did in

its simple one ; in its pure and uncombined

state it is analogous to what is absurdly

called latent heat ; in its compound, or combined

state, it is called sensible heat, or fire.

CHAPTER XXL

ON THE LAWS OF MOTION.

AFTER the different properties, which have

been shown essentially to belong to the solid and

to the liquid to the expansible and elastic

matter of which the world is composed ; it will,

I trust, be readily admitted, that instead of

being one and the same, they are altogether

and absolutely different from each other. If a

general review of the whole system of nature

indeed be taken, it will lead us to conclude, that

a regular chain, of order and of subordination

subsists not only in the common matter of

which it is composed, but also in the various

orders of animated beings it contains.

The analogy that subsists between the different

links of this vast chain is so close, and their

gradation so easy, that it is often very difficult

to say, where the one ends, and the other begins

; what are the different marks by which

406 LAWS OF MOTION.

some parts of the animal kingdom are distinguished

from the vegetable, and some species

of the vegetable from the animal, until its final

termination in the human species. Although

the relation and similitude which the various

individuals bear to the species, as well as the

different species to the same genus, are great

and striking; there, notwithstanding, subsists

shades of difference between every part; so

that when the extremes are compared, instead

of analogy, there is a total difference between

them. Vast and immense as the chasm actually

is which separates both, it, notwithstanding,

is filled up by a regular procession of be*

ings, both animal and vegetable, until it finally

terminates again in inanimate and formless matter;

all possessing different powers, faculties and

aptitudes, concatinating the two extremes : the

perfect with the imperfect, the rational with the

irrational, the active with the passive, the simple

with the compound, the organised with the

disorganised ; until we arrive at, and are forced

to acknowledge, the existence of elementary

matter, of which the universe is composed and

filled, as manifested by the regular gradation in

the elements of light and air, of water, and of

earth.*

* From what has been said, it will appear, that I do not

.consider air as an original element, but as a compound, which

LAWS OF MOTION. 407

It has been in direct violation of these self-

-evident truths, of the absolute and essential

-difference which exists in the different species

of matter existing in the universe, that the

Newtonian laws of nature are founded, 1. By

supposing that reaction was always equal, and

contrary, to action, he has confounded capacity

with power things inanimate with animated

beings, and demanded a condition of

things to exist, which has no existence, space

without matter. 2. By insisting on the doctrine

of universal gravitation, he has confounded under

the same law, bodies whose properties are toto

coelo different from .each other; toe has not

only confounded matter solid and fluid, opake

and rare, active and passive, but even extended

this unnatural law to the whole planetary

system ; and finally concluded, that the motion

of the heavenly bodies are governed by the

same laws as the rotten apple that fell from

the tree in his garden, and which laid the foundation

for the whole of the system. Had that

has been formed, and which serves as a connecting medium,

between the solid and the liquid parts of the earth, and the

matter of light. An element, strictly speaking, is not produced

by any composition ofdifferent species of matter; but

becomes the primary agent, in the process of composition ; or

as JOHNSON elegantly expresses it,

* It is the first and constituent

principle of any thing.’

408 TLAWS OF MOTION.

tree, however, been immersed in water, and

not in air, instead of the apples falling to the

ground, they would haVe risen to the surface of

the water, and, it is probable, that we should

not have had at this day to complain of the

universal principles which have been formed

from a partial solitary fact. After having endeavoured

to prove, that gravitation is only a

relative, and not a positive term ; and that reaction

cannot be equal, or greater than action ;

but that it must be less ; I shall now proceed

to show, that the two remaining laws on which

the Newtonian philosophy is founded,, are

equally unnatural and erroneous, and that they

only require to be examined, in order to be

exposed.

Lex: Corpus onme persevare, in statue suo

quiescendi vel movendi uniformiter in directurn,

nisi quatinus, a viribus impressis cogitur

statum ilium mutare ; or, in other words, that

every body will persevere in its state of rest, or

of uniform motion, in a right line; unless it is

compelled, by some force, to change its state.”

1st. Although this pretended law is applicable

to solid matter only, whenever it is made to

undergo a change from rest to motion, and from

motion to rest, it will appear to be altogether

irrelevant, when it is applied to the government

of the essential property either of air, or of fire,

and more especially of the solar rays ; it is not

LAWS OF MOTION. 409

Vine that either of these bodies are naturally

disposed to persevere in a state of rest, more

than solid matter can persevere in a state of

motion in a right line, unless compelled to

change that state by some external force.

These bodies are essentially active, and when

left to follow their natural power, are in perpetual

motion; so far from persevering at rest,

unless they are moved by a force impressed

upon them, they require a force to be impressed

on them, to prevent them from moving, the

power by which they are able to move, with a

Velocity so immense as they are found to do, is

not derived, but is inherent ; it does not proceed

from external impulse, but from internal

energy ; not vi effecto, but causa motns ; not

from any active, or repulsive, power in the

bodies on which they fall, and from whence

they are reflected ; but owing to an innate quality

which they derive from the source out of

which they emanate.

However admissible the assertion might

be, that the motive power of the sun itself,

might impel the rays from its surface, with a

motion sufficient to traverse the whole of the

planetary spheres ; it is impossible to ascribe

the reflection from inert surfaces on which these

rays have fallen, to any power which those surfaces

possess because a passive body can

never be the cause of action ; nor can motion

410 LAWS OF MOTION.

be effected by a body which is impassive and

immotive. The reflection, therefore, from different

surfaces, which the solar rays are known

to undergo, cannot be produced by any power

inherent in those surfaces, but must be referred

to the self-motive power of the rays alone, by

virtue of the elasticity they essentially contain ;

neither the solar rays, light, fire, nor air,

are indifferent to motion, or to rest ; they are

passive by the influence on them of an external

force, they are self-motive without it.

2d. Neither is the assertion justified by the

fact, that these bodies can ”

persevere in a state

of motion in a right line.” Such is the natural

existence of things in the world, that the matter

of which it is composed, has a constant tendency

to oppose resistance to the motion of a

body passing through it, and which resistance

alters the line of direction which the moving

body would otherwise pursue. The rays of

light are perpetually converged and diverged

from the influence of the medium through

which they pass, and seldom, if ever, move in a

right line. The same variation takes place in

bodies which are impelled to move by an external

force ; the influence of the medium through

which they pass, alters the direction of their

motion, from a right line to a curve; and on

the Newtonian hypothesis itself, the planets describe

curves, and not right lines.

3dly. To suppose that bodies persevere in a

LAWS OF MOTION. 411

of rest, or of motion in a right line, is to

suppose that which never has, and never can

happen; it is necessary to suppose, that there

are situations in which no external agents are

present ; or, if present, that they exert on them

no influence whatever; either that space exists

without matter, or matter without resistance:

a supposition such as this, is not only

without proof, but contrary to proof; a mere

petitio principii; so far, however, from acceding

to the truth of it, I reject, as inadmissible

the principium petitionis ; I reject altogether

the proposition, which requires for its

accomplishment the annihilation of all the

gaseous, the liquid, as well as all the solid

matter of which the world is composed ; for

so long as matter, such as this, continues to

exist, not only the direction in a right line,

which a moving body would describe, will be

perpetually changed, and the motion itself be

ultimately arrested; but the moving body thereby

is from necessity,” and by a sensible and

obvious force,

compelled to change its state.”

And the law ofnature is that as obstacles constantly

intervene, a body once put in motion

cannot move for ever in a right line.

The necessity which a moving body is

compelled of changing its line of motion, in

consequence of the nature of the medium

through which it is impelled, proves that the

.second Newtonian proposition, or law, is not

412 LAWS 6

correct : Mutationem motus proportionaletn

esse vi motrici impressae, et fieri secimdum

lineara rectam qua vis ilia impremiter : namely,

that the mutation of motion, is always

proportionate to the force impressed, and is

always made according to that right line in

which that force is impressed.” However true

it may be, that a given force impressed upon a

body, will give it a given motion, under the same

circumstances of external resistance, it must,

nevertheless, be acknowledged, that the same

force, impressed upon the same body, under

unequal degrees of external resistance, will not

excite on it the same degree of motion ;- the

same force acting on the same body, will produce

a very different result, in a rare, to what

it does in a dense medium ; in air, to what

it does in water; in water, to what it does

when resisted by the solid nucleus of the

world, in which the resistance is so great, that

the same given force, acting upon the same

body, will produce no motion whatever. It is

the resistance which exists which not only tends

to change the direction of the force, by which a

body is moved, but to destroy motion altogether:

the assertion, therefore, is not just, that

the mutation of motion is always proportionate

to the force impressed ; the mutation of motion

depends on the relation which exists between

the force, and the resistance which is opposed

by the body which is to be moved ; neither is

LAWS OF MOTION. 413

the motion produced precisely in the direction

of that force.

4th. Admitting, however, by hypothesis,

what is false in fact, that external resistance

can be abstracted and removed, by the annihilation

of all the matter which filled the medium

through which the moving body was to pass,

I contend that no body whatever, which had

been excited to move, would move for ever,

that is ”

persevere in its state of motion.” A

proposition such as this, is false in fact; because

obstacles constantly exist to retard, and

ultimately to destroy, that motion ; these obstacles

not only reside in the medium, but in the

essential attributes of inertness, and of immobility,

which inheres in the solid matter which

is intended to be moved ; and these attributes

of inertness and immobility, constantly tend to

weaken, and to destroy, the energy of this moving

power. It is to the nature, and to the

efficacy, of the moving power, that is to be

ascribed the motion which is accomplished ;

in order that motion be produced, it is absolutely

necessary that the power should be

active, and that the thing moved should be passive.

And, finally, to produce motion perpetual,

(i. e. perseverance in a state of motion,) the

power must not only be active, but active infinitely

; and the matter moved not passive only,

but passive infinitely.

414 LAWS OF MOTION.

It is demonstrable, that if the agent is finite,

the motion on another body, which that

agent produces, must be finite also, because a

finite power cannot produce an effect which is

infinite. If all the metal which has ever been

separated from the bowels of the earth, were

fused and formed into one gun ; if all the gunpowder

which had ever been manufactured,

were rammed into it; if all the balls that have

ever been made, were melted into one, and

placed upon the powder ; however grand and

terrific the explosion might be ; however far

the ball might be projected, such is the resistance

alone, which would be opposed by the

ball (or the body moved) to the repulsive power

of the gunpowder, that its energy would be

progressively diminished, and be ultimately

destroyed ; and as a natural consequence of

the loss of this energy in the moving power, the

body which had been moved by it, would gradually

verge from motion to rest, and ultimately

become passive and inert.

I would, therefore, call on those who are

disposed to defend this double proposition, to

point out to me, not only where space without

matter is known to exist ; and matter without

resistance; but the finite power which can

produce an infinite effect, an effect which

would, in such a case, not only be different

but better than the cause, whose motion would

LAWS OF MOTION. 415

continue after the energy of the moving cause

was altogether lost. An hypothesis such as

this may subserve the purpose of fiction, not of

truth, and ought not to have been assumed as

the basis, from which the phenomena of nature

are to be explained ; since these phenomena

subsist, independently, and in direct violation

of it. If the whole matter of which the universe

is composed, were in its nature of the

same species as the granite, ofwhich the principal

portion of the nucleus of the earth is formed:

the attraction of gravitation arising from the

quantity of matter might, perhaps, be assumed.

If the solar rays did not radiate throughout the

whole of the planetary spheres, the existence

of a vacuum might, perhaps, be inferred. If

expansible bodies did not dilate by their own

inherent power, to the utmost possible extent,

Comets might be supposed to be bodies fixed,

solid* and opake. If matter did not oppose resistance

to the motion of bodies through it, it is

possible that every body might persevere in its

state of rest, or of uniform motion in a right

line. If all bodies, instead of being active and

passive, were all essentially active, instead of a

plenum, a vacuum existed, it is possible that

reaction might be equal to action. If the sun,

instead of being (what it is reasonable to believe

it is,) a globe of pure light, were a globe

of burning fire, mathematical principles could

41 () LAWS OF MOTION.

ascertain the degree of ice, and of cold, which

existed in Saturn ; of fire and of warmth in*

Venus: and if fire itself, instead of being a

body, the most repulsive, that exists throughout

the whole system of nature, were what it is

not ; if fire were an attracting body, it mighty

in that case, be assumed, that the sun constituted

the attracting centre of the whole planetary

system. If the supposition could be admitted,

which the testimony of all men, of common

sense, in all ages, have absolutely denied

; if it were admitted as a truth, that giants

and pigmies had an actual existence, all the

fictions recorded by that most ingenious man,

DEAN SWIFT, in the celebrated history which

he has given of those renowned kingdoms,

Brobdignag and Lilliput, must be admitted as

incontrovertible truths ; all the phenomena

which took place, may be legitimately deduced

from the principles assumed. So it is, in fact,

with the Newtonian philosophy. If the definitions,

and the laws, contained in thePrincipia,

are once admitted as axioms, or self-evident

truths, which proclaim the attributes which belong

to the different species of simple, and of

compound matter ; the whole chain of events

which take place throughout the whole system

of nature, may be satisfactorily explained.

The relative distances in which the different

planets are situated, as well as the velocity of

LAWS OF MOTION.- 417

the motions which they describe may be ascertained.

It is of importance, however, to observe,

that it was not from a previous knowledge

of the quantity and quality of the matter

of which the planetary system is composed,

that Sir I. NEWTO& discovered, and ascertained>

the times and the revolutions of its difr

ferent parts; but he inferred from the times

which the different planets take to describe

their revolutions, the quantity, as well as the

quality of the matter, belonging to them alL

No conclusion was ever made from a more faU

lacious, or more unphilosophical assumption.

It is not because the indexes of a watch, and of

a clock, describe equal areas in equal times, that

they are necessarily moved by one and the same

cause. A good mathematician, who beholds the

regular motion of the index, round the dial plate,

is able, by means of proper instruments, to ascertain,

in a manner the most precise, that

it moves over the space of an inch and a

half, in one hour’s time ; amounting exactly to

eighteen inches in one day. In like manner, a

good astronomer, by observation, and the aid

of instruments, is able to ascertain, the different

times which the different planets take to

perform their revolutions. Although the mathematician,

and the astronomer, are able by

these means, to ascertain the times and the motions

of these different bodies, the causes of

E E

418 LAWS OF MOTION.

those motions are objects which, in their natureare

altogether separate and distinct ; the motion?

of the index may be caused by the elasticity of

steel, as in a watch ; or by the density and

weight of a piece of iron, as in a clock. The

science, however, which treats of the one, is

entirely separate and distinct from the other.

The same difference prevails with respect to

astronomy; while the motions which the various

planets describe, are mechanical effects, the

cause of these motions is a physical one; while

the science of mathematics is the means by

which different distances and motions, numbers

and magnitudes, are measured and ascertainedj

the science of physics, on the contrary, is conversant

with the nature of the causes, by which

those motions are produced ; it explores the

essential properties of matter ; it distinguishes

the separate attributes of each ; it ascertains

the nature of the active, the aptitude and

capacity of the passive ; the power in the one

of overcomingthe resistance of the other; while

mathematics are merely conversant with effects,

physics, on the contrary, investigate the nature

of came. The causes of natural phenomena are

not to be discovered by mathematical rules, although

the effects may be ascertained by them.*

* I recollect to have seen it observed by some one, that if

any one were to attempt to prove by algebra, how it is that

fire burns ; to explain the nature and operation of the sun by

LAWS OF MOTION. 419

Had Sir I. Newton, confined himself to ascertain,

and to proclaim the effects o.nly that

take place in the planetary system ; there could

have been but one opinion respecting him, and

all must have bowed to that transcendent mathematical

knowledge which he possessed. But

when he attempted to account for the causes

of those effects, (of those motions,) by assuming

that the heavenly bodies were composed of

matter dense and solid, like the earthly matter

of our globe ; that attraction was an innate

force in matter, and that gravitation universally

prevailed ; I contend, that these assumptions on

trigonometry ; or assign the cause of vegetation, and of ratiocination,

from the theory of conic sections, he would deservedly

provoke the laughter, and incur the contempt of all ranks and

degrees of people ; and that he who attempts to guess at

causes, (and it can be called nothing else than guessing,)

merely from 4he appearance and superficies of things that

present themselves, and who makes the mistress wait upon the

handmaid, goes first to work with mathematics, and computes

by observation and experiment, the proportion of the motions

of bodies in particular cases ; and then infers, by deduction,

from what he sees, in such particular cases alone, the causes

of those motions which take place universally and generally.

He who does this, makes very great and fatal mistakes : besides

obstructing the path leading to the knowledge of the

particular fact, it prevents him from coming at any universal

truth. Judging in this way, is judging from effects only;

we see bodies moving, and therefore ought to conclude, that

they move themselves, by an inherent power they possess, or

else that the Deity is substantially present with them, and

moves them by his immediate influence.

420 LAWS OF MOTION.

which his philosophy is founded, were artificial

and unnatural; that although the conclusions

might be true, the principles from whenee these

conclusions were made, were erroneous in the

extreme.

Had the system of nature been considered

as it really is, a system of gradation, and of

difference, emanating from the great first and

universal cause, continued and ended in the

last species

1 of matter, we should not have

had to complain at this time, that bodies of different

species are supposed to be subservient

to one and the same law* that the matter of

fact is mivStaken, and confounded with the

law ; nor be called upon to ascribe to the

thing done (a mere effect) to be the cause and

the power by which these effects are accomplished,*

The difference, however* which exists between

the fact and the law, is as great as between

light and darkness. A law is a rule of

action ; a power, an agent ; by the energy of

which various effects are produced, according

to the rules which thai law prescribes. The

effects which are produced, do not constitute

* It has been well observed by Archdeacon PALEY, that

mechanism is not itself power ; mechanism without power,

can do nothing ; let a watch be contrived and constructed

ever so ingeniously, it cannot go \\ithout a spring, i. e. without

a force independent of, and ulterior to its mechanism.

XA\VS OF MOTION. 421

the law, they are the mere manifestations of

the power of the law. The voluntary muscles

of my body are made to move by the power of

my will ; the motion which is made to take

place, does not constitute the law, it is the

: accomplishment of the law, but is not the law

itself.

The laws which different societies, or nations

have established, for the moral government of

the whole, are rules of action which the individuals

are bound to obey ; the obedience of the

individual to those rules of action, is a proof

of the power of the law ; the power of the law

does not originate, but ends in the act of obedience

; the one is as separate from the other,

&s the power of my foot is separate and distinct

from the shoe which it moves ; as the hand

from the pen, and the pen from the paper ; the

paper constitutes the passive recipient of the

impressions which, through the medium of my

hand, it is made to receive, from my will, the

prime mover of the whole.*

The gradation which exisls in the common

*

Although it is very apparent that the thing done is not the

Jaw, but is the effect which is produced by the law, I am

somewhat surprised to find the late Archdeacon Paley, say,

” that it is a perversion of language to assign any law as the

efficient operative cause of any thing ;” and yet he very properly

declares ” that a law presupposes an agent, for it is

only the mode according to which an agent proceeds.”

422 LAWS OF MOTION.

matter of which the universe is composed, is

not more marked, than in the living beings by

which it is inhabited ; between those which

inhabit the earth only, and those which

are amphibious, of earth and of water, between

those that exist in water only, and

those that exist in water and in air together.

The gradual difference which exists in the

place of their abode, is as evident as in the

organisation and form of which they are severally

constituted; I shall select, by way of illustration,

a few of the organs in each. In the

organs of respiration, the gradation which

exists may easily be traced, from the simplicity

in the fabric of the common trachea, or air cell,

of the vegetable, to the branchiae, or gills, of

fish; from the branchiae, or gills, offish, to the

existence of branchiae and lungs, subsisting together,

in one and the same subject, as in the

syren, until we arrive at lungs only.

The difference may likewise be traced in the

construction of the lungs, from the most simple,

to those ofthe more complicated animals ; from

lungs which consist of large cells, with a small

absorbing surface, as in the amphibia, to the

higher order of animals, that possess lungs with

small cells, and a widely extended surface.

This gradation in the respiratory organs of

different beings, may be traced to the different

organs by which the blood is conveyed. In

LAWS OF MOTION. 423

vegetables, and in the more simple animals, the

blood of both is conveyed to the different parts

of the system, by vessels,whose difference seems

principally to consist in the nature of their form,

whether spiral or straight ; until the fabric of

this organ increases in power and complication,

from a crypta, or one single cavity only ; after

which it is found gradually to increase in its

complication, with additional power, by the aid

of a heart : iii fish the heart has two cavities ;

in the amphibia it has three, and in the mammalia

it has four.

If we were to trace the gradation which exists,

in that wonderful system, which distinguishes

the animal from the vegetable species,

and which is placed, (as PROFESSOR HARWOOD

elegantly expresses it,) “in the doubtful confines

of the material and spiritual worlds,” and more

especially in the attributes which flowfrom it, of

intellect and of soul; we should be compelled to

acknowledge, that the earth below, is connected,

with the heavens above, by different links

of one vast chain, which extends from the first

to the last of things, forming altogether one

perfect whole. We should conclude, that this

universal whole, is the work of a Divine Artificer,

who created it, in the best possible manner,

to answer the ends for which it was especially

designed ; that it is with a view to subserve

those ends, that we behold every particle of

454 LAWS OF MOTION.

matter which exists, possessing a natural and

inherent tendency, a vis insita, as it has been called,

to obey certain rules of rest, or of motion of

unity, or of union according to the particular

class to which it belongs ; by which it is made

to describe, under the same circumstances, the

same phenomena, by which solids fall to the

earth rivers flow into the ocean, by which

gaseous bodies expand and swell on the surface

of both, and are participated by the solar rays,

which warm and illuminate the whole.

It is through the efficacy of these rules, ; that

the planets with order and regularity move

through their allotted spheres,- the changes in

the seasons are formed, and tke divisions of time

established. These rules which have existed

from the moment of the creation, and which, it

is probable, will continue to exist until time

shall be no more, constitute the Laics ofNature,

or rather the instruments, or agents, which the

GOD OF NATURE employs in the physical government

of the material world.

THE END

Advertisements