294 REPORTS ON THE STATE OP SCIENCE.— 1915. 



through February, March, Apjil, May, and the first half of June. A 

 little after the nr-iddle of June the amount of work begins to fall off and 

 continues to do so for the next two or three weeks. Then, through 

 July and August, the curve remains at a lower level than in June, 

 but much higher than during the winter, a somewhat surprising fact. 

 About the end of August people once more begin to work fast, and 

 they go on at an increasing rate until the middle of November. Then 

 the rate begins to fall, but recovers somewhat in December, and finally 

 at the end of that month drops off very rapidly. ' Testing the course of 

 mental work by the marks awarded students at West Point and 

 Annapolis U.S. Military and Naval Academies, 'approximately the 

 same results ' were found. 



Prof. Huntingdon therefore suggests that ' the only satisfactory ex- 

 planation of this seems to be that people's energy varies 10 or 15 per 

 cent, from season to season,' and accordingly he correlates his yearly 

 output curve with the variations in light, open-air life, and temperature 

 that different seasons involve. But temperature he considers has far 

 the greatest influence : 



' It certainly looks as if there were a close relationship between 

 temperature and work, but curiously enough the relationship is in part 

 the reverse of what most people would expect. Low temperature seems 

 much more harmful, and high temperature less harmful than is com- 

 monly supposed.' 



Prof. Huntingdon then compares the output curve in the summer of 

 each single year with the weekly mean temperature then prevailing, 

 and finds that in general the summers of southern New England are less 

 debilitating than the winters. It requires extreme summers, such as 

 are experienced only once or twice in a century, to produce effects as 

 harmful as those of an ordinary winter. Then, ' determining how fast 

 people work on days having various temperatures, no matter in what 

 month they come,' Prof. Huntingdon finds that ' at very low tempera- 

 tures both mental and physical work are depressed. On days with 

 higher temperatures activity of both kinds increases, the increase being 

 slight at first. Mental work reaches its highest point at a temperature 

 of 48° F., while physical work reaches a maximum at 59° P. for men 

 and 60° P. for girls. 



Turning back to his yearly output curve, Prof. Huntingdon sums up 

 that during the part of the year when the temperature passes beyond 

 45 and 70 degrees ' people's work falls off sharply, and when the 

 temperature approaches these limits work increases.' 



One other feature of the curve is noted, however : ' between the 

 limits (45° and 70° P.) (work) does not vary as one would expect, but 

 tends to keep on rising all the time,' an4 suggesting that this is because 

 the temperature keeps changing, and change is a stimulus. Prof. 

 Huntingdon compares the work done in single days with the degree 

 of temperature by which they differed from the pi-eceding day; he finds 

 that when the temperature drops, provided the drop is not excessive, 

 ' human activity is decidedly stimulated. ' 



A further chance of comparing the result on working capacity of 



