From the Eclectic Review.

MARVELS O F HUMAN

WE must be plain with our readers. It | tific inquiry-that is to say, for a period will not do to mince matters where questions of science are concerned. Dainty people, will, no doubt, object to the proposition we are about to advance. Nevertheless, we persist. Fearless of the consequences utterly unawed by the hisses which we know will ensue we proceed to lay down the following assertion: We are all living stoves-walking fire-places -furnaces in the flesh.

bact with the former elements; and if with blushes, say by an unexpected offer their combination is attended with calo--is not a sensation of heat suddenly exrific results in the open air, why should perienced in the countenance? and to not similar demonstrations accompany what can this be ascribed but a direct intheir union in the human interior as far tervention of the nervous power? The as circumstances will permit? effect, it is true, is temporary, and it does "But, pray," exclaims the reader, with not follow that the extra caloric is drawn a strong sense of the indignity which has from special sources, because the captive's been put upon him, by converting his per- capillaries have been stung to wrath, or son into a fire-place, "how and where is because the maiden's have been flushed this combustion effected ?" with delight. But it has been found by Listen, affronted friend! Your twenty-experiment that whatever enfeebles the four pounds of blood are sent to the lungs for aëration at the rate of two ounces for every pulsation. There it takes up a dose of oxygen, of which gas it can absorb one ninth or one tenth of its bulk. Passing through the heart, and propelled into the capillaries, it returns to the lungs loaded with carbonic acid. The oxygen has vanished; that is to say, it has picked up sufficient carbon in its route to convert it into the gas which enlivens champagne and soda water, but kills animals in the Grotto del Carre or the Upas Valley of Java. A small portion, it is true, does not come back in this mephitic form, but the missing quantity is supposed to have combined with hydrogen, producing water, which issues as vapor from the lungs, or is turned to account in the system itself. Here then-to say nothing of other combustible elements, such as sulphur and perhaps phosphorus-we have the unquestionable fact that the oxygen inspired has entered into confederacy with carbon, and consequently as large an amount of heat must have been liberated as if the same transaction had occurred in a grate or a candlestick. It is in the capillary vessels, and therefore in every quarter of the frame, that this process is conducted.

nervous energy, lessens the development of vital heat. Let the nerves be stupefied by narcotics, paralyzed by injuries done to the spinal cord, severed by the knife, or, still more, destroyed by the decapitation of the animal, (for which act a very merciless philosopher is required,) and in these cases the temperature is diminished, and in the latter instance totally annihilated, even though respiration should be partially prolonged. Still, whatever influence may be assigned to the nervous power, the fact that oxygen is perpetually entering the body as a constituent of common air, and returning as a constituent of carbonic acid and moisture, compels us to regard it as the chief, though it may not be the exclusive, source of vital caloric. Dulong and Despretz were of opinion that it could not explain the derivation of more than three fourths of our bodily warmth. Sundry ugly objections have been urged to Dr. Crawford's conclusions as to the difference between the specific capacity of venous and arterial blood. But the great chemical Baron of the day, Liebig, speaks most decidedly on the point: "The combination of a combustible substance with oxygen (says he) is, under all circumstances, the only source of animal heat."

Granting, then, that our bodies are veritable stoves, the exasperated reader will desire to know whence we procure our fuel. Fortunately our coal and firewood are stored up in a very interesting form. They are laid before us in the shape of bread-and-butter, puddings and pies; rashers of bacon for the laborer, and haunches of venison or turtle soup for the epicure. Instead of being brought up

Much has been said, much written, respecting the precise sources of vital caloric. Dr. Black's theory was, that the latent heat of the air and there is enough in any apartment, were it suddenly struck out, to reduce the occupants to a cinder-was partially made sensible in the lungs, and thus communicated to the visiting blood. Some philosophers have voted for an electro-chemical origin: some have demanded for the nervous in scuttles, they are presented in tureens, force a share at least in the management of our internal thermometer. To the latter hypothesis, indeed, some weight must be allowed. When a man is thrown into a passion-as, for instance, by an unexpected arrest; or a lady is covered

dishes, or tumblers, or all of them in pleasant succession. In fact, whenever you send a person an invitation to dinner, you virtually request the honor of his company to take fuel; and when you see him enthusiastically employed on your

dainties, you know that he is literally "shoveling" coke into his corporeal stove. For all food must contain two species of elements, if it is to do its duty efficiently. There must be a portion which is available for the repair of the frame, which will remake it as fast as it is unmade, and which therefore has been called the plastic or body-building material. But there must also be a certain quantity of non-azotized matter, which will combine with oxygen in order that it may undergo combustion. If we take milk, the "model food" of animals, as a criterion of proportion, we shall find that three or four times as much of the latter is needed as of the former. For one pound of simply restorative provender, an energetic man requires four of digestible fuel. The ultimate form in which this fuel is burnt is that of carbon, hydrogen, and sulphur; but proximately we swallow it in the shape of fat, starch, sugar, alcohol, and other less inflammatory compounds. By far the most incendiary of these substances is fat: ten pounds of this material, imported into your stove, will do as much work-that is, will produce as much warmth as twenty-four of starch, twenty-five of sugar, or even twenty-six of spirits.

slender one. Human fat, to use a dock expression, is bonded fuel. It constitutes a hoard of combustible material, upon which the owner may draw whenever his ordinary supplies are intercepted. Should any voluminous gentleman be put upon short commons, or, worse still, upon no commons at all, this reserve fund would be silently invaded, and day by day the sufferer would dwindle down until reduced to an affecting state of attenuation. Let all plump persons therefore rejoice. We offer them our hearty, perhaps somewhat envious, congratulations. They, at any rate, are prepared to stand a long siege from cold. Blessed with such dépôts of fuel in their own frames, they are entitled to crow over the spare Cassius-like figures in which no bountiful provision has been made for the season of privation. They, too, can afford to lavish their caloric when lankier mortals have none to sport. Partly in jest, but partly in earnest, a military writer mentions a corpulent soldier who threw out so much heat that his comrades contended for the pleasure of lying near him whilst bivouacking in the field. It is even playfully alleged that some of them would come to warm their hands over him; and it was certain that no man in And a pleasant thing it is to observe the army could dry up a puddle by force how sagaciously the instinct of man has of natural caloric with more celerity than fastened upon the articles which will best this portly hero. Is there not something supply him with the species of fuel he re-positively benevolent in obesity? Under quires. The Esquimaux, for example, is such circumstances, who would not wish extremely partial to oily fare. He does to be philanthropically fat? not know why. He never heard of the doctrine of animal heat. But he feels intuitively that bear's grease and blubber are the things for him. Condemn him to live on potatoes or maize, and the poor fellow would resent the cruelty as much as a London alderman of the old school, if sentenced to subsist on water-gruel alone. And the savage would be perfectly right. Exposed as he is to the fierce cold of a northern sky, every object around him plundering him of his caloric incessantly, what he needs is plenty of unctuous food, because from this he can generate the greatest quantity of heat. On the other hand, the native of the tropics, equally ignorant of animal chemistry, eschews the fiery diet which his climate renders inappropriate, and keeps himself cool on rice or dates, or watery fruits.

Hence we see the reason why a very stout man, if deprived of food, can keep up his corporeal fires for a longer time than a

For the same reason animals which hybernate, like the bear, jerboa, marmot, dormouse, bat, and others, generally grow plump before they retire into winter quarters. Upon this capital of corpulence they subsist during their lethargy, the respiration being lessened, the pulse reduced to a few beats per minute, and the temperature lowered to perhaps 30° or 40°. But when the season of torpor terminates, they issue from their caves and burrows, meagre and ravenous, having burnt up their stock of fuel; Bruin himself appearing to be anxious to defraud the perfumers of the unguent which is so precious in their eyes.*

* It need scarcely be remarked that the doctrine of Vital Heat applies to animals as well as to men. All have their stores as well as we; but for want of alone. It may suffice at present to say that some space, we confine our observations to human caloric creatures exhibit a higher temperature than the lords of creation. Birds are the hottest; they reach about

Such then being the stove, and such | the heat of the human interior and the the fuel, let us now advert to one or two average heat of a latitude like ours, repreof the peculiarities which this remarkable sents the whole difference between sumapparatus exhibits. It has been justly mer and winter. If the surplus warmth. eulogized on the score of its surprising of the inhabitants of this kingdom-that economy. None of its caloric, we may which we possess over and above what say, is wasted; the whole is expended in the climate itself affords could be collectwarming the frame, from its innermost ed, it would fuse great masses of iron, or recesses to the tips of the fingers and the burn a town to tinder. extremities of the toes. To maintain the temperature of any apartment at 98° for threescore years and ten would involve a bill of some little severity at the coal-merchant's. But the quantity of combustible matter actually consumed upon our human premises is comparatively small. From ten to fifteen ounces of carbon are daily expelled from the lungs, or discharged through the skin, of an adult whose stove is in full practice. The hydrogen and other trifles should also be taken into account in our budget of fuel; but as the total quantity of oxygen inhaled in a year was computed by Lavoisier at 700 or 800 pounds only, and as all chemical combinations are effected in definite proportions, the maximum amount of combustibles employed may be ascertained with some approach to truth.* To express the results numerically, it has been said that the caloric produced in a year would raise twenty or twenty-five thousand pounds of water from the freezing to the boiling point. But perhaps a more vivid conception may be obtained by considering that the difference between

103° or 104°. Even the duck, with all its aquatic propensities, has warmer blood than man. Most mammifers may be quoted at 100° though considerable differences exist. In the heart of a lamb the thermometer rose to 107°. In contradistinction to mammals and birds, reptiles and fishes have been designated "cold blooded;" but this assertion is semewhat calumnious: for though their heat varies with the medium in which they exist, their temperature is generally a few degrees higher. Even insects, crustacea, molluscs, and other invertebrate "small deer," down to the most insignificant polyp,

appear to take out a license to distill caloric on their

own premises. Further, certain plants, whilst absorbing oxgen and making carbonic acid, as in the process of inflorescence, become much warmer than the surrounding air; whilst the temperature of the latter was only 66°, an Arum cordifolium has been known to range from 111° to 128°.

*Lavoisier's estimate is certainly low. To saturate 800 lbs. of oxgen with carbon alone, 300 lbs. of the latter would be required. This would scarcely admit of a pulmonary discharge of 10 ozs. of charcoal

a day, were the whole oxygen employed in producing carbonic acid, and the cutaneous respiration

thrown out of consideration.

The case is still more remarkable in regard to the occupants of the Polar wastes. If the corporeal caloric of these barbarians could be communicated to their atmosphere, so as to impregnate the region with the same temperature, the aspect of the locality would be completely changed. An Arctic landscape would be a scene where tropical fruits might flourish in the open air, where palms might rear their slender stems and banyans spread their awful shade, where tigers might lurk in the thickets and boas lie coiled in the treacherous foliage above, and where the waters might be employed in fanning these British conquerors with punkahs, or carrying them in palanquins on a trip to the Magnetic Pole.

But perhaps the most striking feature in this warmth-producing apparatus, is the self-regulating power which it possesses. The fires on our domestic hearths decline at one moment and augment at another. Sometimes the mistress of the house threatens to faint on account of excessive heat: sometimes the master endeavors to improve the temperature by a passionate use of the poker, with an obligato acexcessive cold. Were such irregularities companiment of growls respecting the to prevail unchecked in our fleshy stoves, we should suffer considerable annoyance. After a meal of very inflammatory materials, or an hour spent in extraordinary exertion, the gush of caloric might throw the system into a state of high fever. How is this prevented? In some of our artificial stoves little doors or slides are employed to control the admission of air: in furnaces connected with steam-engines, we may have dampers which will accomplish the same purpose by the ingenious manipulations of the machine itself. But neither doors nor dampers, pokers nor stokers, can be employed in the bodily apparatus. If, on the one hand, our human fires should begin to flag from undue expenditure of heat, the appetite speaks out sharply, and compels the owner to look round for fuel. Hunger rings the

bell, and orders up coals in the shape of savory meats. Even rags and insufficient clothing contribute to make a man voracious. Or should the summons be neglected, the garnered fat, as we have seen, is thrown into the grate to keep the furnace in play. If, on the other hand, the heat internally developed or externally applied should become unreasonably intense, a very cunning process of reduction is adopted. When a substance grows too hot, the simplest method of bringing it into a cooler frame is to sprinkle it with water, the conversion of the fluid into vapor involving the consumption of a large amount of caloric. This is precisely what occurs in our human organisms. But, doubtless, when we mention the word perspiration, the reader, still more deeply disgusted, will tell us that this is an extremely uncouth topic, and that we ought to blush for referring to such a coarse, illbred operation. Not in the least! On the contrary, we venture to submit that perspiration is an exceedingly philosophical process. Instead of thinking slightly of a person who may happen to be in that condition, we ought to esteem him as one who is in a highly scientific state of body. For no sooner does the temperature of the frame rise above its standard hight, than the sudorific glands, indignant at the event, begin to give out their fluid sensibly, so as to bathe the surface of the flesh. Each little perspiratory pipe (and there are supposed to be six or seven millions of pores with twenty-eight miles of glandular tubing attached) discharges its stream of moisture as if it were the hose of a fire-engine, so that the skin is speedily sluiced, and further incendiary proceed ings are arrested. Whenever, therefore, a man becomes overheated by working, running, rowing, fighting, making furious speeches at the hustings, or other violent exertions, he invariably resorts to this species of exudation, and his friends begin to be alarmed lest he should fairly deliquesce.

jurors, like the old Spanish Saludores, the Italian Lionetti, the English Richardsons and Powells, have earned a daring liveli hood by their salamandrine feats; and though in these cases impunity was generally secured by artificial preparations, yet we know that some of their marvels, such as dipping the finger into molten lead, may be accomplished with safety by any one who chooses to try the experiment.

Drs. Blagdon and Fordyce remained for some time in an apartment where the glow of the air sufficed to roast eggs and dress steaks-drying the latter indeed so as to put them out of the pale of mastication; yet the blood in their veins was not put on the simmer. You would have expected them to suffer like Master Phaëton, when "nec tantos sustinet æstus; ferventesque auras velut e fornace profundâ, ore trahit.” But no, their breath chilled their nostrils in the act of expiration; it sank the mercury in the themometer several degrees; it cooled their fingers if directed upon them; and this it did, though the atmosphere around them acted like a sirocco when set in motion; and though a fan, instead of producing a pleasant breeze, would have compelled the strongest-minded lady to faint, however determined her nerves. What protected these fire-proof_men? Simply, their sudorific glands. The sweat poured down their frames, and if any of our dainty friends had stood in their places, they would doubtless have been ashamed of the pools of perspiration which were formed on the floor.

What shall we say then, good reader? Speaking seriously, and looking at the question from a mere human point of view, could any project appear more hopeless, than one for burning fuel in a soft delicate fabric like the human body-a fabric composed for the most part of mere fluids-a fabric which might be easily scorched by excess of heat or damaged by excess of cold? Does it not seem like a touch of Quixotism in Nature, to design a stove Hence too arises the singular power of with flesh for its walls, veins for its flues, bearing for a time a temperature which skin for its covering? Yet here, we have would parch the body into mummy were seen, is an apparatus, which, as if by it divested of life. Bakers will venture magic, produces a steady stream of heat into ovens where the heat is considerably-not trickling penuriously from its founabove the boiling point. Chantrey, the tains, but flowing on day and night, winsculptor, entered a drying-kiln where the ter and summer, without a moment's cesthermometer indicated 350°. Chabert, sation from January to December. Carry the fire-king, plunged into an atmosphere this splendid machine to the coldest rewhich ranged from 400° to 500°. Con- gions on the globe-set it up in a scene