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such a diversity of forma, shades, and colours, are me result of the combinations of " four or five natural substances—caloric, light, water, air, and carbon." '1 When we consider," says Mr. Partes, *' that the many thousand tribes of vegetables are not only all formed from a few simple substances, but that they all enjoy the same sun, vegetate in the same medium, and are supplied with tho same nutriment, we cannot but be struck with the rich economy of Nature, and are almost induced to doubt the evidence of those senses with which the God of nature has furnished us. That it should be possible so to modify and intermingle a few simple substances, and thence produce all the variety of form, colour, odour, &c. which are observable in the different families of vegetables, is a phenomenon too astonishing for our comprehension. Nothing short of Omnipotence could have provided such a paradise for man."—Chymical Caicchism, chap. 9.
8oft soil your Incense, herbs, and fruits, and flowers.
In mingle*! clouds to Him, whose sun exalts, Who!e breath perfumes you, and whose pencil paints." Tttomton.
What an admirable view is here opened up of the economy of divine wisdom, and of the beneficent care which has been taken to secure the comfort and happiness of every living creature: and how ungrateful a disposition must it indicate in rational beings to overlook such benevolent arrangements! It is highly probable, that in all Other worlds disposed throughout the universe an infinite diversity of scenery exists, and that Do one globe or system exactly resembles another; and yet, it is probable, that the primary elements of matter, or the few simple svos/anees of which our world is composed, may be of the same nature as those which form the constituent parts of every other system; and may give birth to all the variety which exists throughout ihe wide extent of creation, and to all the changes and revolutions through which the different systems may pass, during every period of infinite duration.
2. From this science we have every reason to conclude, that matter is indestructible. In the various changes that take place in material substances, the particles of matter are not destroyed, but only assume new forms, and enter into new combinations. When a piece of wood, for example, is burned to ashes, none of its principles are destroyed; the elementary substances of which it was composed are only separated from one another, and formed into new compounds. Carbon, as already stated, appears to be indegiructible by age, and to preserve its essential properties in every mode of its existence. That Being, indeed, who-created matter at first, may reduce it to nothing when he pleases; but it is highly improbable that his power will ever be interposed to produce this eflect; or that any
particle of matter which now exists will ever be annihilated, into whatever new or varied combinations it may enter. When any particular world, or assemblage of material existence, has remained in its original state for a certain period of duration, and accomplished all the ends it was intended to subserve in that state, the materials of which it is composed will, in all probability, be employed for erecting a new system, and establishing a new series of events, in which new scenes, and new beauties und sublimities, will arise from new and varied combinations. For the Creator does nothing in vain. But to annihilate, and again to create, would be operating in vain; and we uniformly find, thai in all the arrangements of Deity in the present state oj things, Nature is frugal and economical in all her proceedings; so that there is no process, when thoroughly investigated, that appears unnecessary or superfluous.
From the fact, that matter appears to be indestructible, we may learn, that the Creator may, with the self-same materials which now exist around us, new-model and arrange the globe we inhabit, after the general conflagration, so as to make a more glorious world to arise out of its ashes; purified from those physical evils which now exist; and fitted for the accommodation either of renovated men, or of other pure intelligences. From the same fact, combined with the consideration of the infinite diversity of effects which the simple substances of nature are capable of producing, we may be enabled to form a conception of the ease with which the Creator may new-model our bodies, after they have been dissolved in the dust; and how, from the same original atoms, he may construct and adorn them with more glorious firms and more delightful and exquisite senses than they now possess.
In short, the rapid progress which chymical science is now making, promises, ere long, to introduce improvements among the human race, which will expand their views of the agency of God, counteract many physical evils, and promote, to an extent which has never yet been experienced, their social and domestic enjoyment. The late discoveries of chymistry tend to convince us, that the properties and powers of natural subjects are only beginning to be discovered. Who could have imagined, a century ago, that an invisible substance is contained in a piece of coal, capable of producing the most beautiful and splendid illumination—that this substance may be conveyed, in a few moments, through pipes of several miles in length—and that a city, containing several hundred thousands of inhabitants, may be instantly lighted up by it, without the aid of either wax, oil, or tallow? Who could have imagined, that one of the ingredients of the air we breathe is the principle of combustion—that a rod of iron may bo made to bum with a brilliancy that dazzles the eyes— that a piece of charcoal may be made to burn with a white and splendid light, which is inferior only to the solar rays—and that the diamond is nothing more than carbon in a crystallized state, and differs only in a slight degree from a hit of common charcoal 1 Who could have surmised, that a substance would be discovered, of such a degree of levity, as would have power sufficient to buoy up a number of men to the upper parts of the atmosphere, and enable them to swim, in safety, above the regions of the clouds? These are only specimens of still more brilliant discoveries which will, doubtless, be brought to light by the researches of future generations. We have reason to believe, that the investigations of this science will, in due time, enable us to counteract most of the diseases incident to the human frame; and to prevent many of those fatal accidents to which mankind are now exposed. Davy's safety lamp has already preserved many individuals from destruction, when working in coal mines; and thousands, in after ages, will be indebted to this discovery, for security from the dreadful explosions of hydrogen gaa. And, we trust, that the period is not far distant, when specific antidotes to the diseases peculiar to the different trades and occupations in which mankind are employed will be discovered; and the health and vigour of the mass of society be preserved unimpaired, amidst all the processes in which they may be engaged. In fine, the rapid progress of chymical discovery carries forward our views to a period, when man, having thoroughly explored the powers of nature, and subjected them, in some measure, to his control, will be enabled to ward off most of those physical evils with which he is now annoyed, and to raise himself, in some degree, to *he dignity and happiness he enjoyed before moral evil had shed its baleful influence on our terrestrial system. Such a period corresponds to many of the descriptions contained in the Sacred Oracles of the millenial state of the church; when social, domestic, moral, and intellectual improvement shall be carried to the utmost perfection which our sublunary station will permit; when wars shall cease; when the knowledge of Jehovah shall cover the earth; when every man shall sit under his vine and fig-tree, without being exposed to the least alarm; and when there shall be nothing to hurt nor destroy throughout I.he church of the living God. And, therefore, we ought to consider the various discoveries and improvements now going forward in this and other departments of science, as preparing the way for the introduction of this long-expected and auspicious era.
lit A TO MV- AND PHYSIOLOGY.
The general object of both these sciences is o investigate and describe the structure and
economy of the animal frame. Anatomy dissects dead bodies, physiology investigates tir« functions of those that are living. The former examines the fluids, muscles, viscera, and all the other parts of the human body, in a state of real, the latter considers them in a state of action.
The parts of the human body have been distinguished into two different kinds—solids and fluids. The solid parts are bones, cartilages, ligaments, muscles, tendons, membranes, nerves, arteries, veins, hair, nails, and ducts, or line tubular vessels of various kinds. Of these solid parts, the following compound organs consist; the brain and cerebellum; the lungs; the heart, the stomach; the liver; the spleen; the pancreas; the glands; the kidneys; the intestine *; the mesentery; the larynx; and the organs of sense— the eyes, ears, nose, and tongue. The fluid parts are, the saliva, or spittle, phlegm, serum, the chyle, blood, bile, milk, lympha, urine, the pancreatic juice, arid the aqueous humour of the eyes. The human body is divided into three great cavities—the head; the thorar, or breast; and the abdomen, or belly. The head is formed of the bones of the cranium, and encloses the brain and cerebellum. The thorax is composed of the vertebra of the back, the sternum, and true ribs; and contains the heart, the pericardium, the breast, and the lungs. The abdomen is separated from the thorax by means of the diaphragm, which is a fleshy and membranous substance, composed, for the most part, of muscular f,bres. This cavity is formed by the lumbar vertrbrre, the os sacrum, the ossa innominata, the false ribs, the peritonaeum, and a variety of muscles. It encloses the stomach, intestines, omentum, or caul, the liver, pancreas, spleen, kidneyw, and urinary bladder. Without attempting any technical description of these different pars, which could convev no accurate ideas to a general reader, I shall merely state two or three facts in relation to the system of bones, muscles, and blood-vessels, as specimens of the wonderful structure of our bodily frame.
The Bones may be regarded as the prop-work or basis on which the human body is constructed. They bear the same relation to the animal system, as the wood-work to a building. They give shape and firmness to the body; they support its various parts, and prevent it from sinking by its own weight; they serve as levers for the muscles to act upon, and to defend the brain, the heart, the lungs, and other vital parts, from external injury. Of the bones, some are hollow, and filled with marrow; others are solid throughout; some are very small — others very large; some are round, and others Jlat; some are plane, and others conves or concave ;—and all these several forms pre requisite for the situations they occupy, and the respective functions they have to perform. The spine, or back-bone, consists of 24 vertebra, or small bones connected together by cartilages, articulations, and ligaments; of which •even belong to the neck, twelve to the back, and five to the loom. In the centre of each vertebra there is a ho'.e rrx the lodgment and continuation of the spinal marrow, which extends from the brain to the rump. From these vertebrae the arched bones called ribs proceed; and seven of them join the breast-bone on each side, where they terminate in cartilages, and form the cavity of the thorax or chest. The 6ve lower ribs, with a number of muscles, form the cavity of the abdomen, as above stated. The spine is one of the most admirable mechanical contrivances in the human frame. Had it consisted of only three or four bones, or had the holes in each bone not exactly corresponded and fitted into each other, .he spinal marrow would have been bruised, and life endangered at every bending of the body. The skull is composed of ten bones, and about 51 are reckoned to belong to the face, the orhits of the eyes, and the jaws in which the teeth are fixed. There are seldom more than 16 teeth in each jaw, or S2 in all. The number of bones in a human body is generally estimated at about lAo; of which there are reckoned, in the skull, head, and face, 81 ; in the trunk, 64; in the arms, and hand*, 60, in the legs, and feet, 60. The bones are provided with ligaments or hinges, which hind and fasten them together, and prevent them from being displaced by any violent motion; and, that the ligaments may work smoothly into one another, the joints are separated by cartilages or gristles, and provided with a gland for the secretion of oil or mucus, which is constantly exuding into the joints; so ihat every requisite b provided by our benevolent Creator, to prevent pain, and to promote facility of motion. "In considering the joints," says Dr. Paley, " theta is nothing, perhaps, which ought to move our gratitude more than the reflection, haw welt thry wear. A limb shall swing upon its hinge or play in its socket many hundred times in an hour, for 60 years together, without diminution of agility; which is a long time for any thing to last—for any thing so much worked as the joints are."
The Muscular System.—A muscle is a bundle of fleshy, and sometimes of tendinous fibres. The fleshy fibres compose the body of the muscle; and the tendinous fibres the extremities. Some muscles are long and round; some plain and circular; some are spiral, and some have straight Sbres. Some are double, having a tendon running through the body frorn head to tail; some have two or more tendinous branches running through, with various rows and orders of fibres. All these, and several other varieties, are essentially requisite for the respective offices they have to perform in the animal system. The muscles constitute the fiVshy part of the human body, -nd give it that varied and beautiful form we observe over all its surface. But their principal
design is to serve as the organs of motion. They are inserted, by strong tendinous extremities, into the different bones of which the skeleton is composed j and, by their contraction and distention, give rise to all the movements nf the body. The muscles, therefore, may be considered as so many cords attached to 'he bones , and the Author of nature has fixed them according to the most perfect principles of mechanism, so as to produce the fittest motions in the parts for the movement of which they are intended.
One of the most wonderful properties of the muscles is, the extraordinary force they exert, although they are composed of such slender threads or fibres. The following facts, in relation to this point, are demonstrated by the celebrated Borelli, in his work, "De Motu Animalium.n When a man lifts up with his teeth a weight of 200 pounds, with a rope fastened to the jaw-teeth, the muscles named temporalis and masseter, with which peoplechew, and which perform this work, exert a force of above 1 o.OOOIbs. weight. If any one hanging his arm directly downwards lifts a weight of 20 pounds, with the third or last joint of his thumb, the muscle which bends the thumb and bears that weight exerts a force of about three thousand pounds. When a man, standing upon his feet, leaps or springs upwards to the height of two feet, if iho weight of such a man be 150 pounds, the muscles employed in that action will exert a force 2000 times greater; that is to say, a force of about three hundred thousand pounds. The heart, at each pulse or contraction, by which it protrudes the blood out of the arteries into the veins, exerts a force of above a hundred thousand pounds. Who can contemplate this amazing strength of the muscular system, without admiration of the power and wisdom of the Creator, who has thus endued a bundle of threads, each of them smaller than a hair, wiih such an astonishing degree of mechanical force! There have been reckoned about 446 muscles in the human body, which have been dissected and distinctly described; every one of which is essential to the performance of some one motion or other, which contributes to our ease and enjoyment; and, in most instances, a great number of them is required to perform their different functions at the same time. It has been calculated, that about a hundred muscles are employed every time we breathe. "Breathing with ease," says Dr. Paley, "is a blessing of every moment; yet, of all others, it is that which we possess with the least consciousness. A man in an asthma is the only man who knows how to estimate it."
The Heart and Btood-vetsels.—The heart is a hollow muscular organ, of a conical shape, and consists of four distinct cavities. The two largest are called ventricles, and the two smallest auricles. The ventricles *eno' out the blood to the arteries; the auricles receive it from the ..ems. The heart is enclosed in the pericardium, a membranous bag, which contains a quantity of water, or lymph. This water lubricates the heart, and facilitates all its motions. The heart is the general reservoir of the blood. When the heart contracts, the blood is propelled from the right ventricle into the lungs, through the pulmonary arteries, which, like all the other arteries, are furnished with valves that play easily forward, but admit not the blood to return toward the heart. The blood, after circulating through the lungs, and having there been revivified by coming in contact with the air, and imbibing a portion of its oxygen, returns into the left auricle of the heart, by the pulmonary vein. At the same instant, the left ventricle drives tho blood into the aorta, a large artery which sends ofT branches to supply the head and arms. Another large branch of the aorta descends along the inside of the back-bone, and detaches numerous ramifications to nourish the bowels and inferior extremities. After serving the most remote extremities of the body, the arteries are converted into veitu, which, in their return to the heart, gradually unite into larger branches, till the whole terminate in one great trunk, called the vena cava, which discharges itself into the right auricle of the heart, and completes the circulation. Each ventricie of the heart is reckoned to contain about one ounce, or two tables poonsfull of blood. The heart contracts 4000 times every hour; and, consequently, there passes through it 250 pounds of blood in one hour. And if the mass of blood in a human body be reckoned at an average of twenty-five pounds, it will follow that the whole mast of blood passes through the heart, and consequently through the thousands of ramifications of the veins and arteries, fourteen timet every hour, or about once every four minutes. We may acquire a rude idea of the force with which the blood is impelled from the heart, by considering the velocity with which water issues from a syringe, or from the pipe of a fire-engine. Could we behold these rapid motions incessantly going on within us, it would overpower our minds with astonishment, and even with terror. We should be apt to feel alarmed on making the smallest exertion, lest the parts of this delicate machine should bo broken or deranged, and its functions interrupted. The arteries, into which the blood is forced, branch in every direction through the body, like the roots and branches of a tree; running through the substance of the bones, and every part of the animal frame, till they are lost in such fine tubes as to be wholly invisible. In the parts where the arteries are lost to the sight, the veins take their rise, and in their commencement are also imperceptible.
Respiration,—The organs of respiration are the lungs. They are divided into five lobes; three !f which lie on the right, and two on the
left, side ol the thorax. The substance of the lungs is chiefly composed of infinite ramifies tions of the trachea, or windpipe, which, aftei gradually becoming more and more minute, terminate in little cells, or vesicles, which have a free communication with one another. At each inspiration, these pipes and cells are filled with air, which is again discharged by expiration. In this manner, a circulation of air, which is necessary to the existence of men and other animals, is constantly kept up as long as life remains. The air-cells of the lungs open into ihe windpipe, by which they communicate with the external atmosphere. The whole internal structure of the lungs is lined by a transparent membrane, estimated at only the thousandth part of an inch in thickness; but whose surface, from its various convolutions, measures fifteen square feet, which is equal to the external surface of toe body. On this thin and extensive membrane innumerable veins and arteries are distributed, some of them finer than hairs; and through these vessels all the blood of the system is successively propelled, by a most curious and admirable mechanism. It has been computed, that the lungs, on an average, contain about 280 cubic inches, or about Ave English quarts of air. At each inspiration, about forty cubic inches of air are received into the lungs, and the same quantity discharged at each expiration. On the supposition that 20 respirations take place in a minute, it will follow, that, in one minute, we inhale 600 cubic inches; in an hour, 48,000; and in a day, one nniitun. one hundred and fifty-two thousand cubic inches—a quantity which would fill seventyseven wine hogsheads, and would weigh fiftythree pounds troy. By means of this function, a vast body of air is daily brought into contact with the mass of blood, and communicates to it Its vivifying influence; and, therefore, it is of the utmost importance to health, that the air, of which we breathe so considerable a quantity, should be pure, and uncontaminated with noxious effluvia.
Digestion.—This process is performed by the stomach, which is a membranous and muscular bag, furnished with two orifices. By the one, it has a communication with the gullet, and by the other, with the bowels. The food, after being moistened by the saliva, is received inio the stomach, where it is still farther diluted by the gastric juice, which has the power of dissolving every kind of animal and vegetable substance. Part of it is afterwards absorbed by the lymphatic and lacteal vessels, and carried into the circulate ing system, and converted into blood for supplying that nourishment which the perpetual waste of our bodies demands.
Perspiration is the evacuation of the juices of tne body through the pores of the skin. It haa been calculated that there are above three hundred thousand millions of ports in the glands of tha skin which covers the body of a middle-sized man. Through these pores, mure than one-half of what we eat and drink passes off* by insensible perspiration. During a night of seven hours' sleep, we perspire about forty ounces, or two pounds and a half. At an average, we may estimate the discharge from the surface of the body, by sensible and insensible perspiration, at from half an ounce to four ounces an hour. This is a most wonderful part of the animal economy, aid is absolutely necessary to our health, and even to our very existence. When partially obstructed, colds, rheumatisms, fevers, and other inflammatory disorders, are produced; and were it completely obstructed, the vital functions would be clogged and impeded in their movements, and death would inevitably ensue.
Sanation,—The nerve* are generally considered as the instruments of sensation. They are soft white cords which proceed from the brain and spinal marrow. They come forth originally by pairs. Ten pair proceed from the medullary substance of the brain, which are distributed to all parts of the head and neck. Thirty pair proceed from the spinal marrow, through the vertebrae, to all the other parts of the body; being forty in all. These nerves, the ramifications of which are infinitely various and minute, are distributed upon the heart, lungs, blood-vessels, bowels, and muscles, till they terminate on the skin or external covering of the body. Impressioos of external objects are received by the brain from the adjacent organs of sense, and the brain exercises its commands over the muscles and limbs by means of the nerves.
Without prosecuting these imperfect descriptions farther, I shall conclude this very hasty sketeh with the following summary of the parts of the body, in the words of Bonnet. "The bones, by their joints and solidity, form the foundation of this fine machine: the ligaments are strings which unite the parts together: the muscles are fleshy substances, which act as elastic springs to put them in motion: the nerves, which are dispersed over the whole body, connect all the parts together: the arteries and veins, like rivulets, convey life and health throughout: the heart, placed in the centre, is the focus where the blood collects, or the acting power by means of which it circulates and is preserved: the issngtj by means of another power, draw in the external air, and expel hurtful vapours: the stomach and intestines are the magazines where every thing that is required for the daily supply is prepared: the brain, that seat of the soul, is formed in a manner suitable to the dignity of its inhabitant: the senses, which are the soul's ministers, warn it of all that is necessary either for ttspleasure or use.* Adorable Creator! with what wonderful art hast thou formed us!
* Contemplation of Nature, vol. 1. p. 64.
Though the heavens did not exist to proclaim thy glory; though there were no created being on earth but myself, my own body might suffice to convince me that thou art a God of unlimited power and infinite goodness."
This subject suggests a variety of moral and religious reflections, but the limits to which I am confined will permit me to state only the following:—
1. The economy of the human frame, when seriously contemplated, has a tendency to excite admiration and astonishment, and to impress us with a sense of our continual dependence on a superior power. What an immense multiplicity of machinery must be In action to enable us to breathe, to feel, and to walk! Hundreds of bones, of diversified forms, connected together by various modes of articulation: hundreds of muscles to produce motion, each of them acting in at least ten different capacities, (see p. 40;) hundreds of tendons and ligaments to connect the bones and muscles; hundreds of arteries to convey the blood to the remotest part of the system; hundreds of veins to bring it back to its reservoir the heatt; thousands of glands secreting humours of various kinds from the blood; thousands of lacteal and lymphatic tubes, absorbing and conveying nutriment to the circulating fluid; millions of pores, through which the perspiration is continually issuing; an infinity of ramifications of nerves, diffusing sensation throughout alt the parts of this exquisite machine; and the heart at every pulsation exerting a force of a hundred thousand pounds, in order to preserve al! this complicated machinery in constant operation! The whole of this vast system of mechanism must be in action before we can walk across our apartments! We admire the operation ofa steam-engine, and the force it exerts. But, though it is constructed of the hardest materials which the mines can supply, in & few months some of its essential parts are worn and deranged, even though its action should be frequently discontinued. But the animal machine, though constructed, for the most part, of the softest and most flabby substances, can go on without intermission in all its diversified movements, by night and by day, for the space ot eighty or a hundred years; the heart giving ninety-six thousand strokes every twenty-four hours, and the whole mass of blood rushing through a thousand pipes of all sizes every four minutes! And is it man that governs these nice and complicated movements? Did he set the heart in motion, or endue it with the muscular force it exerts? And when it has ceased to beat, can he command it again to resume its functions? Man knows neither the secret springs of the machinery within him, nor the half of the purposes for which they serve, or of the movements they perform. Can any thing more strikingly demonstrate our dependence