130 
BIOLOGY: E. HUNTINGTON 
This seems to suggest a slight rise in the optimum as one goes from 
cooler to warmer climates, but it is doubtful whether the inference is 
justified. The mean temperature of Pittsburgh averages only 3° F. 
warmer than that of southern Connecticut, and it is not likely that so 
small a difference could cause an equally great difference in the optimum. 
The relatively high optimum in Florida may arise partly from the fact 
that the people whose work was tested at Tampa were Cubans coming 
from a climate even warmer than that of Florida. Little weight can 
be placed on such a conclusion, however, because the Cubans were 
engaged in cigar making and in this work high temperature, especially 
when accompanied by moisture, makes the tobacco pliable and hence 
enables people to work rapidly. Thus the apparent optimum is raised 
a little. Moreover, in the present study no account is taken of the 
effect of humidity upon human energy. This factor is of much import- 
ance and probably accounts for a large part of the variation in the 
apparent temperature optimum from place to place. 
(3) Strength tests. In Denmark Lehmann and Pedersen some years 
ago carried on a series of tests of the strength of school children at all 
seasons. When due allowance is made for the normal growth of the 
children it appears that they were strongest when the temperature 
averaged not far from 59°. For 16 months during 1915 and 1916 the 
writer was fortunate enough to secure the cooperation of the teachers 
at Hampton Institute, Virginia, The strength of 11 negro students 
was tested daily with a dynamometer. The young men were strongest 
at an average temperature of 61°. An equal number of young women 
were tested in the same way, but they were working under abnormal 
conditions in a hot, steamy laundry. Accordingly their apparent 
optimum was at an average outside temperature of only 52°. 
Summing up the results of these various methods it appears that the 
death-rate of millions of individuals indicates an optimum at 63° or 
64°. The factory work of thousands of people points to the same tem- 
perature as the best for human activity. Tests of the strength of in- 
dividuals suggest a slightly lower optimum, at about 60°, but the num- 
ber of cases is small. The investigations of Rosenau and Thompson 
also indicate an optimum at 62° or 63°. Since Finns, Japanese, Ger- 
mans, and Americans all show essentially the same response, it seems 
probable that the optimum temperature for physical activity among 
people in all sorts of climates does not vary far from 63° F. Even a 
long residence in a given climate apparently has little effect in causing 
people to become adjusted to their environment. The Finn still seems 
to find his climate always too cool, while the Cuban finds his too warm. 
