Part 20
As in the beginning every species was created, the first individual of each has served for a model to their descendants. The body of each animal or vegetable is a mould, to which are assimilated indifferently the organic particles of all animals or vegetables which have been destroyed by death, or consumed by time. The brute particles, of which part of their composition was formed, returned to the common mass of inanimate matter; but the organic particles, whose existence is permanent, are again resumed by organized bodies: they are extracted at first from the earth by vegetables, and then absorbed by animals who feed thereon; and thus serve for the support, growth, and expansion of both. By this constant and perpetual circulation from body to body, they serve to animate all organized beings. These living substances in quantity are always the same, and differ only in form and appearance. In fertile ages, and when population is the greatest, the whole surface of the earth seems to be covered with men, domestic animals, and useful plants. But in the times of famine and depopulation, the ferocious animals, poisonous insects, parasitical plants, and useless herbs, resume, in their turn, dominion over the earth. To man these changes are material, but to Nature they are perfectly indifferent. The silk worm so inestimable to the former, is to the latter only a caterpillar of the mulberry tree. Though this caterpillar, which so materially assists in the supply of our luxuries, should disappear; though the plants, from which our domestic animals procure their nourishment, should be devoured by other caterpillars; though still others should destroy the substance of our corn before the harvest; in short, though man and the larger animals should be starved by the inferior tribes, Nature would not be less abundant nor less alive; she never protects one at the expence of another, but especially supports the whole. As to individuals she is regardless of number; she considers them only as successive images of the same impression; as passing shadows of which the species is the substance.
In earth, air, and water, then, there exists a certain quantity of organic matter which cannot be destroyed, but which is constantly assimilated in a certain number of moulds, that are perpetually undergoing destruction and renewal: these moulds, or rather individuals, tho' varying in number in every species, are nevertheless always the same, that is, proportioned to the quantity of living matter; and this appears to be absolutely the case, for if there were any redundance of this matter, or if it were not at all times fully occupied by the individuals of the species which exist, it would, most assuredly, form itself into new species, for being alive it would not remain without action; and once uniting with brute matter is sufficient to form organized bodies; and it is by this constant combination, and invariable proportion, that Nature preserves her form and consistence.
The laws of Nature, both with respect to the number of species and of their support and equilibrium, being fixed and constant, she would invariably have the same appearance, and be in all climes absolutely the same, if her complexion did not so completely vary in almost every individual form. The figure of each species is an impression, in which the principal characters are so strongly engraven as never to be effaced; but the accessory parts and shades are so greatly varied that no two individuals have a perfect resemblance to each other; and in all species there are a number of varieties. The human species, which has such superior pretensions, varies from white to black, from small to great, &c. The Laplander, the Patagonian, the Hottentot, the European, the American, and the Negro, though the offspring of the same parents, have by no means the resemblance of brothers.
It is evident, therefore, that every species is subject to individual differences, but that each of them does not equally possess the constant varieties which are perpetuated through successive generations; the more dignified the species, the less changeable is its figure, and the less are the varieties of it. The multiplication of animals being inversely in proportion to their magnitude, as the possibility of variation must be in exact proportion to the numbers they produce, there consequently must be more varieties among the small than the large animals; and also, for the same reason, there will be a greater number of species which seem to approach each other; for the unity of the species in the large animals is more fixed, and the nature of their separation more extended. What a number of various and similar species surround those of the squirrel, the rat, and other small quadrupeds, while the massy elephant stands alone, without a compeer, and at the head of the whole.
The brute matter, of which the body of the earth is principally composed, is a substance that has not undergone many alterations, though the whole has more than once been disturbed and put in motion by the hand of Nature. The globe of the earth has been penetrated by fire, and afterwards covered and disordered by water. The sand, which occupies the interior parts of the earth, is a vitrified matter; and the layers of clay, by which its surface is covered, are nothing but the same sand having been decomposed by the operation of the waters. Granite, free-stone, flint, nay, all metals, are composed of this same vitrified matter, whose particles have been condensed or separated, according to the laws of their affinity. These substances are totally destitute of animation; they exist, and will continue to do so, independently of animals and vegetables. There are, however, many other substances, which, although they have the appearance of being equally inanimate, originate from organized bodies; and of this description are marble, lime-stone, chalk, and marl; they being composed of the fragments of shells, and of those small animals which by transforming the water of the sea into stone, produce coral, and all the madrepores, whose varieties are numberless, and whose quantity are almost immense. Pit-coal, turf, and many other substances found in the upper strata, are also of this nature, they being only the residue of vegetables which have been more or less corrupted or consumed. Besides these, there are other substances which have been produced by the second action of fire upon original matter; these are but few in number, and consist of such as pumice-stones, sulphur, the scoria of iron, asbestos, and lava. To one or other of these three great combinations may be referred all the relations of brute matter, and all the substances of the mineral kingdom.
The laws of affinity, by which the various particles of these different substances separate from each other, in order to unite among themselves and form homogeneous masses, are perfectly similar to that general law by which the celestial bodies act upon each other; in both cases their exertions are the same. Globules of water, of sand, or of metal, have the same influence, and act upon each other as the earth acts upon the moon; and if the laws of affinity have hitherto been deemed different from those of gravity, it is because the subject has been considered in a very confined point of view. The mutual action of celestial bodies is very little influenced by figure; their distance from each other is so very great, that this is necessarily the case; but when they are not far asunder, then the effect of figure is considerable. For instance, if the earth and moon, instead of spherical figures, were both short cylinders, and exactly equal throughout in their diameters, their reciprocal action would be very little varied from what it is at present, because the distances of all their parts from each other would be very little changed. But if these two globes were cylinders of great extent, and approached near to each other, the law of their reciprocal action would seem to be different, inasmuch as the distances of their parts would be greatly varied; and hence whenever figure becomes a principle in distance the law will appear to vary, although in fact it is always the same.
The human intellect guided by this principle, may advance one step further in penetrating into the operations of nature. The figure of the constituent particles of bodies still remains unknown; we cannot entertain the smallest doubt that water, air, earth, metals, and all homogeneous particles, are composed of elementary particles, which are perfectly similar, although we are still ignorant of their figure. By the aid of calculation this at present unknown field of knowledge may be disclosed by posterity, and the figure of the elementary bodies be ascertained with tolerable precision. They may take the principle we have established as the basis of their enquiry; namely, "that all matter is attracted in the inverse ratio of the square of the distance; and this law seems to admit of no variation in particular attractions but what arises from the figure of the constituent particles of each substance, because this figure enters as an element or principle into the distance;" and having once discovered, by repeated experiments, the law of attraction in any particular substance, they may then, by the aid of calculation, be able to trace the figure of its constituent particles. To render this point more clear, let us suppose, that by placing mercury on a perfectly polished surface, repeated experiments prove that this fluid metal is always attracted in the inverse ratio of the cube of the distance; it will then become necessary to investigate what figure gives this expression; and this figure will be certainly that of the constituent particles of mercury. If it should appear, by such experiments, that the attraction of mercury was in the inverse ratio of the square of the distance, it would be clearly demonstrated that its constituent particles were spherical, because a sphere is the only figure which observes this law, and at whatever distance globes are placed the law of their attraction is always the same.
Newton had some idea that chemical affinities (which are nothing more in fact than these particular attractions which we have mentioned) were produced by the same kind of laws as those of gravitation; but he does not appear to have perceived that all those particular laws were merely simple modifications of the general one, and that their apparent difference arose solely from the circumstance of the figure of the atoms, which attract each other, having, when at small distances, a greater influence upon the force of this law than the mass of matter.
It is, notwithstanding, upon this theory that the perfect knowledge of brute matter depends. The basis of all matter is the same, and its form throughout would be perfectly similar, if the figures of its constituent particles were not different; and thus it is that one homogeneous substance can differ from another only in proportion to the difference of their original particles. A body composed of spherical particles ought to be one half specifically lighter than that whose particles are cubical, because as the first only touch each other by their points, they leave intermediate spaces equal to what they occupy, whereas the cubical particles join without leaving the smallest interval, and must consequently form a matter half as heavy again. Although the figures are considerably varied, that variation is by no means so great as we might imagine, since Nature has fixed the limits of lightness and gravity. Gold and air, with respect to density, are the two extremes, and therefore all the figures in Nature must be comprehended as coming between those two; such as would have produced heavier or lighter substances have been rejected.
In speaking of figures, as employed by Nature, I do not mean to imply that they must be necessarily, or are exactly, similar to those geometrical figures which we form in our imagination. We form laws by supposition, and then endeavour to render them simple by abstraction. It is very possible that there are neither exact cubes nor perfect spheres in the universe; but as nothing certainly exists without form, and as from the variation of substances the figures of the elements are different, some of them most undoubtedly must approach to the sphere, the cube, and all the other regular figures which we have conceived. The precise, absolute, and abstract figures which our minds are so frequently induced to admit, cannot have any existence, because all objects are related, and differ only by almost imperceptible shades. It is by the same rule that when I speak of one substance as being entirely full, because composed of cubical particles, and another as being not more than half full, because its parts are spherical, I mean only comparatively, and not that such substances really exist; for experience has fully informed us that in transparent bodies, such as glass, which is both dense and heavy, there is but a small quantity of matter in proportion to the extent of the intervals; nay, as we have before observed, it might be demonstrated that even gold, which is the most dense species of matter, has more vacuities than substance.
To investigate the powers of Nature is the object of rational mechanics, while active mechanics is solely confined to a combination of particular powers, and consequently the art of constructing machines. This art has at all times been certain of cultivation from necessity and convenience; and both ancients and moderns have equally excelled in it. But rational mechanics is a science invented in our days; for, from the days of Aristotle to those of Descartes, even the philosophers have reasoned no better upon the nature of motion, than uniformly to mistake the effect for the cause. Impulsion was the only force with which they were acquainted; to it they attributed the effects of others, and all the phenomena of the universe. If this idea of theirs had been probable, or even possible, impulsion, which they regarded as the sole cause, must have been a general effect, which equally belonged to all matter, and which equally exerted itself in all places, and at all times; but every day demonstrated the contrary to be the fact; for they must have perceived that this force had no existence in bodies at rest; that it had but a short subsistence in projected bodies, being soon destroyed by resistance; that a fresh impulse was absolutely necessary for its renewal, and that, consequently, so far from being a general cause, it was only a particular effect produced by others more general.
It is true, however, that we ought to consider a general effect as a cause, for we cannot become acquainted with the real cause of this effect, because all our knowledge is derived from comparison; and as there is not any thing to which we can compare an effect, which is supposed general, and equally belonging to every thing, we can know it only by the fact. According to this view, attraction, or gravity, being a general effect common to all matter, and clearly evinced by the fact, ought to be considered as a cause; and to which all particular causes should be referred, nay even that of impulsion, since it is less general and less constant; and the principal difficulty is to perceive how impulsion can be an effect of attraction; for if we rest on the communication of motion by impulse, we are then persuaded that it can only be transmitted from one body to another by elasticity, and that all the hypotheses, which suppose a communication of motion in hard bodies, are mere ideal fancies, which do not exist in Nature. A perfectly hard or a perfectly elastic body is entirely imaginary, as neither of them really exist; for it is certain that nothing exists absolutely or in extreme; and the idea of perfection must suppose one or the other.
It is certain that if there were no elasticity in matter there would be no impulsive force; for instance, if we throw a stone, the motion it acquires is communicated by the elasticity of the arm. When motion is communicated by one body in action encountering another at rest, how can we possibly suppose it to be done otherwise than by compressing the spring of the elastic particles it contains, which recovering itself almost immediately after, gives to the whole mass a force equal to that which it received? How a perfectly hard body should admit this force, or receive motion, is beyond comprehension; and the enquiry is unnecessary, since no such body exists; for, all bodies are endowed with elasticity. The force of electricity is proved by experiments to be elastic, and to belong to matters in general; and therefore, if no other elasticity existed in the interior parts of bodies but that of this electrical matter, that would be sufficient for the communication of motion; and consequently to this great spring, as a general effect, the particular cause of impulsion must be attributed.
A little reflection on the mechanism of elasticity will convince us that its force depends on that of attraction. To have a still more clear idea of this subject, let us suppose a spring the most simple, such as of a solid angle of iron, or of any other hard substance, and then see what will be the result of compressing it. By compression we oblige the parts adjacent to the top of the angle to bend, or to separate a little from each other; but the pressure being removed they again approach as near as they had done before. Their adhesion, from which the cohesion of bodies results, is clearly an effect of their mutual attraction. Upon the spring being pressed this adhesion is not destroyed, because, although the particles are separated, they are not removed beyond the sphere of their mutual attraction; consequently the moment the pressure is taken away the force is renewed, the separated parts draw near, and their spring is restored. But if the pressure be too violent, they will, in that case, be removed beyond the sphere of their attraction, and the spring will break, because the compressing force will be greater than that of cohesion, or that of mutual attraction, by which the particles are kept together. This proves that elasticity can only exert itself in proportion to the cohesion of the particles of matter, that is, in proportion as they are united by the force of their mutual attraction; from which it results, that elasticity in general, which alone can produce impulsion, and impulsion itself, are owing to the force of attraction, and are only particular effects which depend on that general one.
Notwithstanding that these ideas appear to be perfectly clear to me, I do not expect to see them adopted. People in general reason only from their sensations, and natural philosophers determine from their prejudices; as, therefore, both these must be set aside, very few will remain to form a proper judgment; but such is the dignity of Truth, that she is content with a few admirers, and is always lost in a crowd; she is at all times august and majestic, notwithstanding which she is frequently obscured by fantastic opinions, and obliterated by fanciful chimeras. I, however, view and understand Nature in this manner, and am almost induced to believe that she is still more simple; the phenomena exhibited by brute matter is caused by a single force, and from this force, combined with that of heat, originate those living particles which gave rise to, and support all, the various effects of organized bodies.
FINNIS.
T. Gillet, Crown-court, Fleet-street.
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Transcriber Note
All obvious typographical errors were corrected. Where several variant spellings were used, the most prevalent version was use to standardize them. Although the printed version capitalized the first word in the major sections, they are presented as first letter only capital. On page 188, the odd fraction of 87 divided by 1 was left as printed. In addition to obvious typographical corrections, the following were made:
Page(s) Change ======== ================= 134 "proxility" changed to "prolixity" 135-143 Best judgement used in the table where numbers not clearly decipherable in the best images available 142 BISMUTH, with Antimony starts with 10004 all others start with 10000. The "4" assumed typo changed to "10000". 143 Shows 10,0000. the last '0' assumed typo and removed. 167 Twice shows a fraction of "16/11 of gold". Although this may be a typo for "10/11 of gold" it was left unchanged. 248 "aoules" changed to "aoutes"