154 
ZOOLOGY: BENEDICT, FOX AND BAKER 
Proc. N. A. S. 
ameter probably exceeds 300 light years, since two of the variables are 
more than 170 light years distant from the center of the cluster. 
It is of interest to recall that the study of the brightest stars in N. G. C. 
7006 has shown no effect of selective scattering of light in space. It also 
appears, from the agreement of the parallax based on angular diameter 
with the values based on magnitude methods, that the general non- 
selective absorption of light is inappreciable in the direction of N. G. C. 
7006, even when the distance involved is, as in this case, 225,000 light-years. 
1 Mt. Wilson Contr., No. 152. p. 13, 1917; Astroph. J. Chic, 48, 1918 (166). 
*Mt. Wilson Contr., No. 152, p. 14, n-l, 1917; Ibid., 48, 1918 (167). 
3 Aft. Wilson Contr., No. 156, pp. 1-6, 1918; Ibid., 49, 1919 (249-54). 
A ML Wilson Contr., No. 161, pp. 16-18, 1918; Ibid., 50, 1919 (122-4). 
THE SKIN TEMPERATURE OF PACHYDERMS 
By Francis G. Benedict, Edward L. Fox, and Marion L. Baker 
Nutrition Laboratory, Carnegie Institution oe Washington, 
Boston, Mass., and New York Zoological Park, New York City 
Read before the Academy, April 26, 1921 
A knowledge of the temperature of the skin is of great assistance in 
interpreting the laws governing the loss of heat from the animal organism, 
but with warm-blooded animals, such as birds and many mammals, the 
skin temperature is determined only with difficulty, because of the cover- 
ing of hair or fur. With humans, also, the protective clothing inter- 
feres with the accurate determination of skin temperature, for numerous 
observations have shown that even under ordinary clothing the skin tem- 
perature of man is by no means constant and, due to the protective covering, 
is undoubtedly much higher than it would otherwise be. It seemed, 
therefore, that records of the skin temperature of certain hairless animals 
would be of value, since the factor of covering would thus be eliminated. 
Accordingly, we took advantage of the excellent material at the New York 
Zoological Park and of the friendly cooperation of Mr. Raymond L. 
Ditmars to make such observations, and as a result are able to report the 
surface temperatures of two elephants, one rhinoceros, and a hippo- 
potamus, all presenting large hairless surface areas. 
The method employed was that described in an earlier communication. 1 
The apparatus consists of two copper-constantan thermo-junctions, with 
special means of application to the skin to secure the true skin temperature 
rather than the resultant of skin and environmental temperature. One 
junction is kept in a thermos bottle with a carefully calibrated thermom- 
eter, which is read practically every minute or two, and the other junction 
applied to the skin. The difference in temperature between the 
two junctions is noted on a galvanometer, whose "constant" is likewise 
checked every few minutes. 
