110 Proceedings of the Boyal Society of Edinburgh. [Sess. 
XI. — An Investigation into the Effects of Seasonal Changes on 
Body Temperature. By Sutherland Simpson, M.D., D.Sc. 
(From the Physiological Laboratory of the Medical College, and the 
Department of Poultry Husbandry, New York State College of 
Agriculture, Cornell University, Ithaca, N.Y., U.S.A.) 
(MS. received January 6, 1912. Read February 19, 1912.) 
CONTENTS. 
Introduction ...... 
PAGE 
. 110 
Present Investigation ..... 
. 112 
Results and Discussion .... 
. 130 
Summary . ...... 
. 135 
Introduction. 
Very little is known regarding the influence of the different seasons of the 
year on the body temperature either of the lower animals or of man. John 
Davy * in 1845 published the results of daily observations on his own tempera- 
ture in England, extending from August 6 to April 30 (with the exception of 
the month of October), and of those made at the same hour (7-8 a.m.), the 
highest (100° F.) was recorded on January 7, and the lowest (98*1°) on 
February 9. The average monthly figures were as follows : — August 98*7° F., 
air 61° F. ; September 98*8°, air 66°; November 98*9°, air 51°; December 
98*7°, air 42°; January 98*8°, air 45° ; February 98’6°, air 42° ; March 98*74°, 
air 46° ; April 98*66°, air 54*6°. They show a remarkable constancy. A 
more extensive series was made at Barbadoes in the West Indies, covering a 
period from July 1845 to November 1848. The minimum monthly mean 
temperature (98*3° F.) was found in August 1845, and the maximum 
(98*76° F.) in August, September, and October 1848; there was no evidence 
of any regular seasonal rhythm. 
These observations of Davy, however, although frequently referred to 
in the books, are of little value, since the temperature was taken in the 
mouth and not in the rectum. It has been shown by Lindhard f and others, 
that in the case of most individuals, readings obtained from the mouth are 
* John Davy, Phil. Trans., London, 1845, part ii., p. 319, and 1850, p. 437. 
t Lindhard, “ Investigations into the Conditions Governing the Temperature of the 
Body,” Danrnark-Ekspeditionen til Gronlands Nordostkyst , 1906-1908, Copenhagen, 1910. 
