August 11, 1916] 



SCIENCE 



189 



Connecticut, as determined by their 

 monthly wages for piece work, over a period 

 of four years. He found that the annual 

 course of production was as follows : Low 

 1 at the beginning of the calendar year, it fell 

 still lower and reached its minimum at 

 about the end of January; through the 

 spring there was a gradual increase in out- 

 put until June; then a moderate decrease 

 until the end of July ; in the autumn an in- 

 crease to the maximum in November; and 

 then the winter descent to the succeeding 

 January minimum. Production was thus 

 greatest in the spring and the autumn, and 

 least in the winter and the summer. A very 

 similar course was followed by the workers 

 engaged in making electrical apparatus in 

 Pittsburgh; and similar confirmation of 

 the validity of the conclusions, with changes 

 in details, was made by the output of other 

 industrial workers in the southern states 

 and by strength-tests of school children in 

 Denmark. All these data combine to dem- 

 onstrate that the greatest physical efficiency 

 of the individual is found not during the 

 summer or the winter, but at intermediate 

 seasons. That the same is true also of men- 

 tal activity is shown by a study of the 

 marks secured by the students at West 

 Point and Annapolis in certain classes, 

 especially mathematics. Of the various 

 climatic features of the different seasons 

 that might be responsible for these seasonal 

 differences in achievement, temperature ap- 

 pears to be the most important. Both phys- 

 ical and mental activity seem to be great- 

 est and most effective, not when extreme 

 summer's heat or extreme winter's cold pre- 

 vails, but when the body is subjected to an 

 intermediate temperature. After a careful 

 consideration of his many figures Hunting- 

 ton came to the conclusion that the optimum 

 temperature of the outside air for the phys- 

 ical work of human beings is about 60° F. 

 (15.6° C.) and for the mental work about 



40° F. (4.4° C.) the greatest total efficiency 

 of the human body culminating at the inter- 

 mediate point of 50° F. (10° C). 



We have thus seen that the body reacts to 

 changes in atmospheric conditions in mani- 

 fold ways. The most potent of the atmo- 

 spheric agencies is undoubtedly tempera- 

 ture, but high temperatures exert greater 

 effects when they are accompanied by high 

 humidity. I have said little of the move- 

 ment of air, but it should be understood 

 that movement is an important agency, and 

 its share in the physiological phenomena 

 has been studied by the New York Commis- 

 sion. By way of genera] summary it may 

 be said that when an existing external tem- 

 perature is fairly comfortable to the indi- 

 vidual an elevation of it, especially when 

 such elevation is accompanied by an in- 

 crease of humidity, is deleterious, and the 

 deleterious effects are more pronounced 

 when the air is stagnant. Deleterious ef- 

 fects resulting from such a combination of 

 atmospheric conditions may be in some de- 

 gree obviated if the air next the skin be put 

 into motion, but a more effective antidote 

 is a reduction in the temperature of the 

 air, and this may be assisted by a reduction 

 in its humidity. All experimentation and 

 observation go to demonstrate that a mod- 

 erately cool and moderately dry air in mo- 

 tion constitutes the most physiologically 

 helpful aerial envelope of the body. The 

 customary figure of 70° F. (approximately 

 21° C.) for the atmosphere in which most 

 persons engage in the ordinary occupa- 

 tions of the living room of a dwelling is too 

 high; a range from 65° to 68° F. (approxi- 

 mately 18°-20° C.) with not over 50 per 

 cent, relative humidity, is undoubtedly 

 better, but even such temperatures are too 

 high when much physical activity occurs. 

 Depending on activity and on more obscure 

 corporeal conditions the same external tem- 

 perature may feel at one time warm and at 



