44 REPORT — 1842. 



All living creatures whose existence depends on the absorption of oxygen, 

 possess within themselves a source of heat independent of the medium in 

 which they exist. This heat, in the Professor's opinion, is wholly due to the 

 combustion of the carbon and hydrogen contained in the food which they 

 consume. Animal heat exists only in those parts of the body through which 

 arterial blood, (and with it oxygen in solution) circulates ; hair, wool, or 

 feathers do not possess an elevated temperature. The carbon and hydrogen 

 of food, in being converted by oxygen into carbonic acid and water, must 

 give out as much heat as if they were burned in the open air. The only dif- 

 ference is, that this heat is spread over unequal spaces of time; but the actual 

 amount is always the same. 



As animal heat depends upon respired oxygen, it will vary according to 

 the activity of the respiratory apparatus of the animal. Thus the temperature 

 of the body of a child is 102°, whilst that of an adult is 99|°. That of birds 

 is higher than that of quadrupeds, or than that of fishes or amphibia, whose 

 proper temperature is 3° higher than the medium in which they live. All 

 animals, strictly speaking, are warm-blooded ; but in those only which pos- 

 sess lungs, is their temperature quite independent of the surrounding medium. 

 The temperature of the human body is the same in the torrid as in the frigid 

 zone. But as the body may be considered in the light of a heated vessel, 

 which cools with an accelerated rapidity, the colder the surrounding medium, 

 it is obvious that the fuel necessary to maintain its heat must vary in different 

 climates. Thus less food is necessary in Palermo, where the temperature of 

 the air is that of the human body, than in the polar regions, where it is about 

 90° lower. 



It has formerly been stated that the quantity of oxygen respired in the 

 colder regions of the earth is greater than that inhaled in the tropics ; and 

 by a more abundant supply of food, a greater generation of heat must ensue. 



The human body may be aptly compared to the furnace of a laboratory 

 destined to effect certain operations. It signifies nothing what intermediate 

 forms the food or fuel of the furnace may assume ; it is finally converted into 

 carbonic acid and water. But in order to sustain a fixed temperature in the 

 furnace, we must vary the quantity of fuel, according to the external tempera- 

 ture, that is, according to the supply of oxygen. 



In the animal body the food is the fuel, and by a proper supply of oxygen, 

 we obtain the heat given out during its combustion. In winter, when we 

 take exercise in a cold atmosphere, we respire a greater amount of oxy- 

 gen, which implies a more abundant supply of carbon in the food ; and by 

 taking this food, we form the most efficient protection against the cold. A 

 starving man is soon frozen to death ; and every one knows that the animals 

 of prey of the arctic regions are far more voracious than those of the torrid 

 zone. 



Our clothing is merely an equivalent for food, and the more warmly we 

 are clothed, the less food we require. Were we to go destitute of clothes, 

 like certain savage tribes, or if in hunting or fishing we were exposed to the 

 same degree of cold as the Samoyedes, we could with ease consume 10 lbs. 

 of flesh, and perhaps a dozen tallow-candles to the bargain, as warmly-clad 

 travellers have related with astonishment of these people. Then could we 

 take the same quantity of brandy or blubber of fish without bad effects, and 

 learn to appreciate the delicacy of train-oil. 



We. thus perceive an explanation of the apparently anomalous habits of 

 different nations. The maccaroni of the Italian and the train-oil of the Green- 

 lander and the Russian are not adventitious freaks of taste, but necessary 

 articles, fitted to administer to their comfort in the climates in which they 



