DR. DAVY ON THE TEMPERATURE OF MAN WITHIN THE TROPICS. 439 
The observations from which these mean results are deduced are so consistent, as 
may be seen by reference to them in detail in the Appendix, as hardly to admit of 
doubt in relation to their accuracy. 
Probably the low morning temperature of the body within the tropics, as shown 
above, may be owing principally to three circumstances, — to the depressing or 
lowering power of sleep, — to the light bed-covering used there, and the free circula- 
tion of the air in the room. A sheet and a thin coverlet were the only protection 
from the air; and the windows mostly being open, the outer air had free access, so 
that towards morning the temperature of the air of the room did not differ from that 
of the external air commonly more than two or three degrees. Moreover, the higher 
temperature observed at night, before going to rest, may have conduced to the lower 
morning temperature noticed on rising, as the lower temperature at night in England, 
with the opposite circumstances as to bed-clothing and air of sleeping-room, may 
have conduced to the higher morning temperature recorded there, — fluctuations 
these in accordance with well-known physiological laws. 
2. Of the Variation of Temperature during different seasons of the year. 
The following Table, formed from the first, exhibits the mean of the observed tem- 
perature during the several months comprised therein, as well as the mean of the in- 
door temperature. 
Mean temperature 
under the tongue. 
Air of 
room. 
Mean temperature 
under the tongue. 
Air of 
room. 
1845. 
1847. 
o 
July . . . 
98-43 
76-00 
January 
98-60 
77-70 
August 
98-30 
80-60 
February ... 
98-53 
80-26 
September ... 
98-60 
81-20 
March 
98-60 
77-40 
October 
98-56 
81-46 
April 
98-53 
78-00 
November ... 
98-46 
80-56 
October 
98-66 
80-83 
December ... 
98-40 
77-90 
November ... 
98-56 
79-66 
1846. 
December ... 
98-36 
77-36 
January 
98-63 
78-16 
1848. 
February ... 
98-60 
77-88 
January 
98-60 
77-06 
April 
98-46 
80-00 
February ... 
98-53 
77-73 
May 
98-66 
81-50 
March 
98-60 
78-40 
June 
98-66 
81-56 
April 
98-60 
78-26 
July 
98-36 
81-00 
May 
98-66 
81-46 
August 
98-70 
81-60 
June 
98-60 
80-86 
September ... 
98-40 
81-36 
July 
98-36 
80-46 
October 
98-73 
81-50 
August 
98-76 
81-56 
November ... 
98-60 
80-60 
September ... 
98-76 
82-26 
December ... 
98-63 
77-96 
October 
98-76 
81-50 
November ... 
98-60 
79-83 
98-54 
79-75 
Comparing the temperature under the tongue with that of the air of the room, it 
will be seen that there is some accordance between them, though not a strict one, as 
if other circumstances than differences of atmospheric temperature have a marked 
