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objects of chemical research. These are comparatively simple, easily composed and decomposed, as the balance of the various attractions of their different particles preponderates. The effects produced are obvious; but of the nature of attraction we are wholly ignorant, though it seems principally concerned in all the changes which are incessantly taking place; even those powerful agents, caloric and the electric fluid, appear to be in some measure connected with it. Hence bodies arrange themselves in the order of their specific gravity. Hence water and the grosser fluids are confined to the surface of the earth, while air, being lighter, occupies the space above; it cannot, however, fly off
, indefinitely; for its particles, though invisible, being solid gravitating matter, are held by the force of attraction near the surface of the earth for the respiration of animals. It is by the attraction between caloric and water, and probably the electric fluid also, that water is raised by evaporation as an invisible fluid, which, in the upper regions, condenses into clouds: the particles of these clouds either unite and descend in rain, or are attracted by the summits of hills and mountains, where they deposit their moisture, which percolating through their strata, breaks out in springs; these, by their union, form rivers, which, proceeding to the sea, supply the waste from evaporation; this evaporation is a distillation upon a grand scale: nothing but pure water is thys raised, which descends in dew or rain for the nourishment of vegetables. Here we trace the operation of powerful causes, while we remain ignorant of their nature; but every thing goes on with such regularity and harmony as to give the most striking and convincing proofs of a combining, directing Intelligence of a present Deity.
“ 4. Any one of these agents uncontrolled would overturn the whole system of things: if attraction were to act without being opposed by caloric, all bodies would shrink up into one inert mass; if, on the other hand, caloric were to prevail, the forms of bodies would be immediately.destroyed. Nothing but that creative power from which they emanated, and who, in his comprehensive view, foresees all possible consequences, could maintain the equilibrium between them, so that they can only act within the limits prescribed to them; they can only exert their power in that direction which is conducive to the ends for which they were created.
“5. If the human powers fail, in attempting to account for the nature of the changes in inert matter, how must its difficulties be increased when we come to consider organized bodies ? Here, in consequence of the addition of the living principle, the attractions of inert matter are surprisingly modified; a seed contains rudiments capable of being expanded into a large tree; every tree has its peculiar form, and is capable of producing the rudiments of others. Here carbon, hydrogen, and oxygen, which;
left to themselves, would form compounds chiefly binary, being absorbed by the organs of the plant, form part of its substance, and are converted into living matter under a more complicated order of affinities. The vegetable, having flourished during a limited period of time, is deserted by the living principle, and the elements of which it is formed, the carbon, hydrogen, and oxygen, attract each other according to the laws which regulate inert matter; and thus the body is decomposed, and furnishes elements or materials for a new generation. It is like pulling down a house and building another with the same materials. No less admirable is the provision by which the tribes of vegetables succeed each other upon the face of the earth. The means for the propagation and preservation of the different species; and the checks which have been established to prevent any of them from exceeding certain bounds, essential to the well-being of the whole, abundantly manifest an order and design which can only be attributed to Infinite Wisdom. But let us advance a step farther, and consider, not only the union of the living principle with matter, but the power of sensation, loco-motion, and instinct superadded. What a field opens before. us in the various classes of animals! Whether we consider the thousands of organized bodies sporting, pursuing, or avoiding each other in a single drop of water, each of which would be more than sufficient to confound all the atheists in the world; or direct our attention to those of larger bulk, what admirable contrivance, what consummate skill in the adaptation of their various organs to their peculiar mode of existence, and to the place which the animal is destined to fill in the scale of created beings,-every one of them doubtless answering some purpose essential to the well-being of the whole, though we may not be able to discover it! How admirable is that instinct which directs the operations of them all, and to which they all invariably adhere! The wood-pigeon was never seen to build its nest like the goldfinch, nor the goldfinch like the swallow: these all uniformly accomplish the will of their Creator, and having passed through the limited period of their existence, give place to their offspring, the increase of which is so regulated as to secure the continuance of the species, and at the same time such checks are provided as to keep them within convenient bounds: and here it is remarkable that those animals which are most prolific are subject to the greatest casualties. Thus in the spawn of fish: though the roe of a single cod would produce more living animals than there are men upon the face of the earth, yet most of them become the prey of other animals, and the equilibrium is constantly preserved. Through all these varying forms of animated beings the original matter is continually passing; the element azote in animals being added to the carbon, hydrogen, and oxygen. Nothing less than the creative power of Omnipotence could add one atom to the mass, or annihilate the
smallest particle of it. Hence it will follow, that air, earth, water, together with the present animals and vegetables, are composed of the same materials as those which existed at the first creation, notwithstanding the revolutions and changes through which, in the series of ages, these original elements must have passed.
“ 6. So far we see a regular gradation of beings, rising in their various degrees from simple life to sensation under all its modified circumstances. Every thing, so far, complete; but a being was .wanted to supply the next link of the chain, and that being is man.
“7. Man, placed at the head of terrestrial beings, differs from other animals by the gift of mind. The mind, or soul, is properly the man; the body is merely a set of instruments by which the mind executes its purposes.
8. “ The human frame is the most perfect of organized bodies, and in it we again observe the same infinitely wise adaptation of means to ends. As in the lower orders of animals each was furnished with organs exactly fitted to its local circumstances, and indespensable to its existence, so in the human body the organs and the senses were bestowed with a reference to mind. Man being endowed with reason, can avail himself of the powers of nature, and make inferior animals subserve his purpose; to him, therefore, the strength of the horse, the elephant, or the lion, was not necessary, any more than that acuteness of some of the senses for which many animals are so remarkable. - It will, however, be instructive to consider the human body with reference to the different senses respectively. It was made erect that it might assume a commanding attitude; and the organs of sight are so placed as to be able to contemplate the heavens, and have an ex. tensive range over the surface of the earth. It was not necessary that the human eye should be as penetrating as that of the hawk or the eagle. Man, when it is necessary for him to see at a dis. tance, can employ a telescope. If his sight had been so microscopic as to see with great distinctness the structure of small insects, and the particles of air, the eye would have been unfit for common purposes, and the mind would have been distracted by the multiplicity of objects. Who can enough admire the wisdom of those laws by which the rays of light are governed! They travel through the regions of unfathomable space with a celerity almost beyond conception, at the rate of nearly 200,000 miles in a second of time. They arrive from different suns and from different systems, crossing each other in all directions without the least interference or confusion; and as it concerns us less to be acquainted with objects at a distance than with those near at hand, so the intensity of light diminishes as the squares of the distances. The light from the sun, striking forcibly upon all the bodies about us, is reflected from their surfaces according to a
fixed and invariable law: some of these surfaces have the power of decomposing a beam of white light, and separating it into its primitive colours ; some bodies reflect rays of one colour, some of another; hence arises an agreeable variety in the aspect of nature, and hence we are enabled to distinguish with greater certainty one body from another. By means of that wonderful organ, the eye, we are made sensible of the distances and forms of bodies.
9. “ All visible bodies reflect the rays of light from every part of their surface in all directions, and yet in consequence of the simple and beautiful law of refraction it is only those rays
which fall in particular angles upon the eye that can produce complete vision. These crossing each other on the optic axis in the centre of the eye produce a picture of objects upon the retina, or expansion of the optic nerve at the back of that organ, and hence produce a sensation in the brain. The eye is so formed, then, as to show us those objects which it most concerns us to be apprised of, with perfect distinctness only when they are at a certain distance. As they recede from us, the impressions are less distinct, and when they are so far as to be of no consequence to us, they no longer obtrude themselves upon our attention, but vanish away. Again, this organ in man is so perfect, that our two eyes, by means of the three pair of muscles which govern each, answer the purpose of that vast quantity of eyes with which the hemisphere on the head of a common house-fly is studded. The coloured part of the eye, or iris, likea delicate veil, regulates the quantity of light admitted. In obscurity it contracts, and the pupil is enlarged; but in a strong light it expands, and diminishes the aperture. The opening is circular in the human being, because a view. was wanted in all directions; but in the cat and tiger it is vertical, their prey being above ; in horses and sheep it is tranverse, for their food lies horizontally. This organ, as well as other parts of the body, is protected by the sense of feeling; and this sense is exquisite in the eye, because it is of such vast importance to us.
The minute ramifications of nerves spread over the surface of the body give us notice of mischief by the sensation of pain. Were it not for this, we might lose a finger, a hand, or an arm, without knowing it. It appears by surgical operations, that this acuteness of feeling is the greatest where it is most wanted for our protection, that is, at the surface of the body; but that some of the internal parts of our frame have comparatively little of it. The provision for the durability of the limbs is no less admirable. If our hands had been made of iron, they would have been worn out long before the termination of an ordinary life; but the parts of the human body are continually re-produced from the blood, which is itself formed from the chyle, a fuid into which the food is converted by the process of digestion, while old parts are taken up by a set of vessels called ab
sorbents, and are carried off in the excretions. To a -certain limited extent, parts which have been lost may be reproduced in the human body: thus a wound will be filled up with granulations, in which new vessels will be formed; but here, again, we remark how every thing is adapted to the nature of the animal; the more perfect the animal, the more irreparable is the loss of a part; thus, in man, an'arm or a leg, a hand or even a finger, if once lost, can never be reproduced; but if a crab lose a leg, or a lobster a claw, the limb, in process of time, is reproduced. This power of reproduction is so great in some of the less perfect animals, that a polypus being cut in pieces, the pieces will produce new animals of the săme kind. - 10. “ The sense of smell, so extremely acute in some of the canine tribe, is precisely adapted in man to his situation, and, while it gives him the power of gratification from the odour of flowers and aromatic substances, it tends to his preservation by warning him of the presence of substances whose effluvia would endanger his health if they were not removed ; thus, by a wise provision of the Author of nature, what would be hurtful is rendered disagreeable.
11, “ The taste, also, answers a double purpose : it renders the necessary act of supplying the stomach with food, agreeable, while, for our preservation, it is so contrived, that many substances, which would be injurious, excite no such sensations, or very disagreeable ones. Some animals, it is probable, have this sense in a higher degree than man. In the accounts of travellers we find that, in uncultivated places, roots fit to be eaten were discovered by observing the kind which the monkeys had selected for their food. The sense of hearing in man, besides tending to his preservation, answers several most important purposes. In him it is not so acute as in some of the lower animals, whose safety depends principally upon it; but, if it had been more so than it is, it would have been extremely inconvenient, and the bustle of the crowded streets of the metropolis perfectly intolerable; it is, however, like all the rest of our senses, just adapted to our situation, and amply sufficient to apprise us of the approach of danger. The ear has been so constructed as to receive pleasure from sounds: these are produced by particles of air agitated by the tremulous motion of the parts of a body vibrating in unison; that is, when the vibrations are multiples of each other, the vibrations of a musical string are almost inconceivably rapid. In the gravest harmonic sound they are 121 in a second, whilst the shrillest sounding body makes 51,100 vibrations in the same portion of time.
12. “ The greatest service rendered to us by the sense of hearing is the facility which it gives of communicating our ideas and feelings to each other. The nature of this faculty, and its importance, are well described by Rollin : Admirable, indeed, are