ANIMAL HEAT. 



649 



whole subject has never been presented in a 

 connected and systematic manner. 



Since it is proved that the temperature of 

 the human body varies, we can only obtain an 

 approximation to its actual amount by taking 

 the mean of all the good observations that 

 have ever been made, being particularly care- 

 ful to include the extremes ; for a mean gives 

 but a very imperfect idea of a term that ought 

 to represent a variable number, if the limits 

 are not at the same time assigned and taken 

 into the account. The best observations of this 

 kind, provided they be sufficiently numerous, 

 will be those that have been made by the same 

 individual, inasmuch as there is great likeli- 

 hood that he will always have made use of the 

 same procedure and of the same instruments, 

 by which the results become more readily com- 

 parable one with another. 



TEMPERATURE OF THE HUMAN BODY. 

 In the following observations we shall make 

 use of the measures of temperature given by 

 Dr. John Davy. These amount to one hun- 

 dred and fourteen in number, and were made 

 on individuals of both sexes and of different 

 ages in three quarters of the world, in Europe, 

 Asia, and Africa, in different latitudes, under 

 various temperatures, and among individuals 

 of different races. But, as the knowledge of 

 the mean and extreme temperatures of the 

 body of man would have little value apart 

 from the statement of the circumstances and 

 conditions under which they were ascertained, 

 we shall at the same time give the ages of the 

 subjects and the temperature of the air at the 

 time of the observations. 



The mean age of the subjects of Dr. Davy's 

 observations was twenty-seven years. The mean 

 temperature of the air was 23, 3 c. (74 F.*) be- 

 tween the limits of 15, 5 (60 F.) and 27, 8 

 (82 F.). In these circumstances the mean 

 temperature of the body, which was always 

 taken in the mouth, was 37, 7 (100 F.) be- 

 tween the extremes 35, 8 (96, 5 F.) and 

 38, 9 (102 F.). The greatest difference in 

 one hundred and fourteen observations, there- 

 fore, scarcely exceeded three degrees. The 

 temperature of the human body thus obtained 

 might be considered as exact if the conditions 

 of age and external atmospheric temperature 

 approached pretty closely to their respective 

 means. This, in fact, was the case as regards 

 the first term, but not as concerns the second ; 

 for some of the observations were made under 

 very intense degrees of heat, such as 27, 8 (82 

 F.), but none at the opposite extreme, or at a 

 temperature which could be reputed cold, a 

 temperature of 15 (59 F.) being already suf- 

 ficiently agreeable. So that if the temperature 

 of the air influences that of the body, a ques- 

 tion which we shall examine by-and-by, the 

 mean which we have stated as the temperature 

 of the species would be too high. 



It is of some consequence to pursue 



* [The valuations according to Fahrenheit's scale 

 the editor desires may be regarded as mere though 

 close approximations to the indications according to 

 the centigrade scale.] ED. 



these inquiries among the lower members of 

 creation, among animals; and the writer to 

 whom we are indebted for the observations 

 quoted upon man has also made a great num- 

 ber upon the lower animals. We shall there- 

 fore continue to make use of this series of 

 experiments, as we have already made use of 

 that which bore upon man individually. 



TEMPERATURE OF THE MAMMALIA. The 

 observations here were made on thirty-one dif- 

 ferent species taken from among the principal 

 divisions of this class, and under a mean tem- 

 perature of the external air equal to 25 (77 

 F.), between the limits of 15 (59 F.) and 30 

 (86 F.). 



The mean temperature of the body of the 

 Mammalia was 38, 4 (101, 10 F.), the max- 

 imum being 40, 5 (105 F.), the minimum 

 37, 2 (99 F.). The extent of variation con- 

 sequently presented by the Mammalia, 3, 3 

 of the centigrade scale (6 F.), is nearly equal 

 to that exhibited by man. But there is this 

 difference between the two scales, that the 

 extremes and the mean in the case of man are 

 inferior to the corresponding terms in the case 

 of the Mammalia. 



TEMPERATURE OF BIRDS. The observa- 

 tions here were made on fifteen species in 

 different orders. The mean temperature of the 

 air was 26, 1 (79 F.), between the extremes 

 15 (59 F.) and 31, 5 (88, 75 F.). The 

 temperature of the subjects of the experiments 

 offered a mean of 42, 1 (107, 86 F.), the su- 

 perior limit being 43, 9 (111 F.), the inferior 

 37, 2 (99 F.). The temperature of birds, 

 therefore, presents a <scale much more exten- 

 sive than that of man and the Mammalia, 

 amounting to as many as 6, 7 degrees centi- 

 grade (12 F.). It also stands above both of 

 the others in the point of its mean, which is 

 higher by 3, 7 (6 F. nearly) in its upper 

 limit, and 5 centigrade (about 9 F.) higher 

 in its lower limit. The lower limit, in fact, 

 corresponds very nearly with the mean term of 

 the heat of the Mammalia as exhibited in the 

 preceding scale. But in neither scale can we 

 say much in regard to the inferior limit, inas- 

 much as no observation was taken at a tem- 

 perature lower than that of fifteen degrees cen- 

 tigrade (59 F.). 



When we compare the preceding statements 

 of the temperature of animals, it is apparent 

 that it varies but little between one species and 

 another of the same class. In passing to dif- 

 ferent classes, however, the difference becomes 

 very considerable, and though the observations 

 are here much fewer in number, they are per- 

 fectly satisfactory as regards the general result. 



TEMPERATURE OF REPTILES. From nine 

 observations made on members of the four 

 orders of Reptiles, Dr. Davy found, the ex- 

 ternal air having a mean temperature of 26, 5 

 (79, 75 F.) between the extremes 32 and 16 

 (89, 5 and 60, 75 F.), that the temperature 

 of Reptiles was not higher than 28 (82, 5 F.). 



TEMPERATURE OF FISHES. If from Rep- 

 tiles we pass to Fishes, corresponding and 

 even more remarkable differences are perceived. 

 Dr. Davy, indeed, gives the temperature of 



