The phenomena of heat in the body is something like that produced by the combustion of fuel, such as coal, only in the body the combustion is slow and the heat far lower than that of flame. The act of breathing is very like the bellows ofa smithT and our food is very much the same as the coals which he puts upon his Hre, It is probable that some heat may bejiroducedin the various secreting organs of thft body, by the Chemical action which takes place in them,— From these two sources animal heat is most probably derived. It is positively certain that the blood is heated at least one degree of Fahrenheit in passing through the lungs ; and that arterial blood is warmer than venous. Most of the phenomena which occur in the production of heat may be explained by attributing it to a combination or a union of the oxygen of the air with thecarbon of the blood in the lungs. This supply of animal heat enables the body to resist the fatal effects of exposure to a low temperature. In the polar regions the thermometer often falls to 108 or 109 degrees below zero; and yet the power of evolving heat, possessed by our bodies, enables us to resist this degree of cold. The temperature of our bodies in that region is about the same that it*would be were they in the warm regions near the equatar. The thermometer, il plunged into the blood of man, in both situations mentioned, would indicate a temperature about the same. Our bodies have nearly the same temperature in both places; because, so to speak, and it is not very absurd, the combustion, or fire in the lungs, gives out more heat, it burns with greater intensity in the polar regions than in the equatorial-. We all know that a large fire will warm our ropms,no matter how cold it may be. We can give our rooms the same temperature in winter that they have in summer, if we regulate our fires accordingly, A little more fuel is all that is requisite for that purpose. Nature has so ordered, that when our bodies are iii_a *!iJea2Per^ure, we inspire more air tfaanlv1ien^^^rTO--TrHi- tomTH-'m*ttra.-~ In other words, she compels us to take in more fuel and increase the combustion in the lungs. The Esquimaux eats blubber, which is mostly all carbon, and the Laps drink plenty ofgrease. In warm countries the foodofthe Lap would kill the negro, and the food of the nations of the West Indies would not be able to keep the Esquimaux from perishing with cold. The temperature olthe human body, and of most warm-blooded animals, is from 98 to 1100 degrees Fahrenheit, and is effected but a [few degrees by any variation of that of the : surrounding atmosphere. Animals are warmblooded when they can preserve nearly an equal temperature, in despite of the atmospheric vicissitudes from heat to cold, and from cold to heat. They have a temperature of their own, independent of atmospheric changes, , The time will soon arrive when thicker clothing must be worn by our citizens at the north. They must line their vests well along the back bone, and provide against freezing, It is a factthafi warm clothes tend to save food, as all animals eat food in proportion to the cold of the atmosphere. This is the reason why cattle that are well housed consume less food, and keep in better condition than those which are shelterless and exposed.
This article was originally published with the title "Heat of the Body" in Scientific American 8, 5, 38 (October 1852)