814 ANIMAL HEAT. 
the depth of winter to the height of summer : in the month of February 
the mean temperature was 40°-8, in April 42°, and in July 43°'77 : from 
this time the temperature began to decline. It was also found that, in 
winter, birds could more readily resist the action of extreme cold than 
in summer. 
Davy 1 observed the temperature of sheep during summer and 
winter, and his results, although they are not sufficiently consistent 
for positive conclusions, seem to show that the temperature of the body 
is a little higher in the warm weather than in the cold. 
The influence of extreme heat and cold. — The experience of 
the inhabitants of tropical climates shows that it is possible to live even 
in an atmosphere the temperature of which at times exceeds that of the 
body, and that the body is able, by means of the cooling effect of the 
evaporation of sweat, to prevent its temperature rising a degree above 
the normal. 
Lining, 2 in 1738, found that the temperature of his axilla was 36°4, 
and that of his mouth 36 0, 7, when the heat in the sun's rays was 51 0- 1, 
in the shade 36°'7, on a hot summer's day in South Carolina. Ellis, 3 in 
1758, observed that the temperature of his body was not above 36°4 
when he was living in Georgia, and the temperature of the air was 
40°"6. Experiments on men and on lower animals have shown that much 
greater heat can be borne for short periods. Blagden and Fordyce 4 
observed their own temperatures after remaining in heated rooms, and 
found that the effect varied according to the amount of moisture 
present ; thus, after remaining fifteen minutes in a damp room heated 
to 54° '4, the temperature of the mouth and urine was 37°'8, but a 
similar exposure in a dry room heated to 115°5 — 126° - 7, and in which 
beefsteaks were being cooked by the heat of the air, did not raise the 
temperature of the body above the normal. Similar experiments were 
made by Dobson, 5 who found that the temperature in the mouth of one 
man rose to 37°'5 after he had remained about fifteen minutes in a 
room heated to 94° "4; in another case the rise was to 38° - 6, after 
twenty minutes' exposure to air at 98° - 9 ; and in a third case a stay of 
ten minutes in a room at 106 o- 7 caused a rise to 38° - 9. 
Tillet 6 had previously observed young girls remain without 
any inconvenience for five or ten minutes in a kiln heated to about 
130,° but he does not give any records of their temperature. In 1747, 
Le Monnier 7 found that he could remain for eight minutes in a bath 
supplied by a thermal spring, the temperature of which was 44° to 45° ; 
at the end of that time his skin was red and swollen, and his distress so 
great that he was obliged to get out. No observations upon the 
temperature of the body are given. Kurrer 8 and Neuhauss 9 have ob- 
served that the temperature of stokers, working in a stoke-hole at 50° 
to 56°, is raised to 37°'6, or even to 38°1. 10 
Numerous experiments have been made to determine the effect of 
1 "Researches," London, 1839, vol. i. p. 20S. 
- Phil. Trans., London, 1748, vol. xlv. p. 338. 
3 Ibid., 1758, vol. 1. pt. 2, p. 754. 
4 Ibid., 1775, vol. lxv. pt. 1, pp. Ill and 484. 
8 Ibid., 1775, vol. lxv. pt. 2, p. 463. 
6 Hist. Acad. roy. d. sc, Paris, 1764, p. 188. 
''Ibid., 1747, p. 271. 
8 Deutsche Vrtljschr. f. off. Gsndhtspflg.. Braunschweig, (2), Bd. xxiv. S. 291. 
9 Virchoivs Archiv, 1893, Bd. cxxxiv. S. 365. 
10 See also Crombie, Indian Ann. Med. Sc, Calcutta, 1S73, vol. xvi. p. 601. 
