LESSON 18 Living stoves
[Animal heat is caused by the union of the oxygen of the air with the carbon derived from the food we eat. This carbon, taken in as a part of our food, and being used to form the tissues of the body, is dislodged. particle by particle, whenever we move a muscle, be it of the heart. lungs, or limbs, and whenever we think or feel; and it is then that the union with oxygen (that is, the combustion takes place.) The more intensely, therefore, we think, and act. and feel, the more carbon we burn, and the more repairs our bodies need. The condition of life is therefore death; and the faster we live the more rapidly are the particles of our bodies burning up—passing away. The following humorous article may help to fix some of these principles in our memories.]
WE must be plain with our reader. It 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, and proceed to lay down the following assertion: We are all living stoves—walking fire-places—furnaces in the flesh.
Now we do not intend to say that any one can light a cigar, or boil an egg, or even ignite a lucifer-match at these human hearths. Still, we repeat, these bodies of ours are stoves—fire-places—furnaces, if these terms can be applied to any apparatus for the express production of heat. And is not heat produced in the human body by the union of oxygen with carbon, just the same as by the burning of wood in an open fire-place? and does not this union take place in the capillaries(1) of the blood-vessels?
But granting that our bodies are veritable stoves, the reader will desire to know where we procure our fuel. Fortunately, our coal and fire-wood 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 labourer, and haunches of venison or turtle-soup for the epicure.(2) Instead of being brought up in scuttles, they are presented in tureens, 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 honour of his company to take fuel; and when you see him enthusiastically employed on your dainties, you know that he is literally "shovelling" fuel into his corporeal stove. The ultimate form in which this fuel is burned in the capillaries is that of carbon, with a little hydrogen and sulphur; but we swallow it in the shape of fat, starch, sugar, alcohol, and other less inflam-matory compounds. By far the most heating 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-five pounds of starch, twenty-five of sugar, or even twenty-six of spirits.
And a pleasant thing it is to observe how sagaciously the instinct of man has fastened upon the articles which will best supply him with the species of fuel he requires. The Esquimau(3) is extremely partial to oily fare. He does not know why. He never heard of the doctrine of animal heat, but he feels intuitively(4) that bear's grease and blubber are the things for him. Condemn him to live on potatoes or Indian corn, and the poor fellow would resent the cruelty as much as an 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 oily food, because from that he can produce 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 slender one. Human fat is fuel laid away for use. It constitutes a hoard of combustible material upon which the owner may draw whenever his ordinary supplies are intercepted. 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.
For the same reason, animals which hibernate,(5) like the bear, jerboa,(6) marmot,(7) dormouse,(8) bat, and others, generally grow plump before they retire into winter quarters. Upon their capital of fat they subsist during their lethargy,(9) the respiration being lessened, the pulse reduced to a few beats per minute, and the temperature perhaps nearly to the freezing point. But when the season of torpor terminates, they issue from their caves and burrows meagre and ravenous, having burned up their stock of fuel; Bruin(10) himself appearing to be anxious to defraud the perfumers of the unguent(11) which is so precious in their eyes.
But perhaps the most striking feature in this warmth-producing apparatus(12) within us 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 endeavours to improve the temperature by a passionate use of the poker, with an occasional growl respecting the excessive cold.
Were such irregularities 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 heat might throw the system into a state of high fever. How is 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 workings 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 around for fuel. Hunger rings the bell and orders up coal in the shape of savoury meats. 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 of the body 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. This is precisely what occurs in our human frames. For no sooner does our internal heat rise above its standard height than the perspiration tubes, with their six or seven millions of openings, indignant at the event, begin to pour out the fluid. so as to bathe the surface of the whole body. Whenever, therefore, a man becomes over-heated, by working, running, rowing, fighting, making furious speeches or other violent exertions, he invariably resorts to this method of quenching the heat, by "pouring on water."
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 strange that a stove should have flesh for its walls, veins for its flues, and skin for its covering? Yet here is an apparatus which, as if by magic, produces a steady stream of heat;—not trickling penuriously from its fountains, but flowing on day and night, winter and summer, without a moment's cessation, from January to December.
Carry this splendid machine to the coldest regions on the globe, set it up where the frosts are so crushing that nature seems to be trampled dead,—still it pours out its mysterious supplies with unabated profusion. It is an apparatus, too, which does its work unwatched, and in a great measure unaided. The very fuel, which is thrown into it in random heaps, is internally sifted and sorted, so that the true combustible elements are conveyed to their place and applied to their duty with unerring precision.
No hand is needed to trim its fires, to temper its glow, to remove its ashes. Smoke there is none, spark there is none, flame there is none. All is so delicately managed that the fairest skin is neither shrivelled nor blackened by the burning within. Is this apparatus placed in circumstances which rob it too fast of its heat? Then the appetite becomes clamorous for food, and in satisfying its demands the fleshy stove is silently replenished. Or, are we placed in peril from superabundant warmth? Then the tiny flood-gates of perspiration are flung open, and the surface is laid under water until the fires within are reduced to their wonted level.
Assailed on the one hand by heat, the body resists the attack, if resistance be possible, until the store of moisture is dissipated; assailed on the other by cold, it keeps the enemy at bay until the hoarded fuel is expended. Thus protected, thus provisioned, let us ask whether these human hearths are not entitled to rank among the standing marvels of creation; for is it not startling to find, that, let the climate be mild or rigorous, let the wind blow from the sultry desert or come loaded with polar sleet, let the fluctuations of temperature be as violent as they may without us, there shall still be a calm, unchanging, undying summer within us?
temperature, degree of heat.
How is animal beat produced? where does the carbon come from? When does the combustion take place? To what may our bodies therefore be compared? What is their fuel? Which is the best fuel? In what countries is it the chief food? What does the native of the tropics prefer? Why can a stout man survive without food longer than a lean man? What are hibernating animals? Give examples. How are they sustained during winter? What is perhaps the most striking feature in our heal-producing apparatus? How does it intimate that more fuel is required? How is excessive heat reduced?