FRESH AIR AND EFFICIENCY 287 



physical work; and that the chemical state of the air 

 (even when the CO 2 exceeds 0.3 per cent) has no such 

 effect. Even a slightly elevated room temperature 

 (of 75 F.) gave results which warrant careful pre- 

 cautions against overheating. In a room of 75 F. 

 about 15 per cent less physical work was done than 

 when the same students were tested at 68 F. ; and 

 at 86 F. the physical work done fell 35 per cent. 

 High temperature had no effect upon the quality of 

 mental work, save in reducing the inclination for it. 

 Furthermore, by means of standard lunches and an 

 estimate of the calories consumed, it was found that 

 the food consumption was 9 percent greater in a well- 

 ventilated atmosphere than in foul air. The value of 

 open-air schools as promoting the physical welfare of 

 children has long been recognized. The constant 

 benefits from such schools include increases in the 

 weight, strength, chest expansion, hasmoglobin con- 

 tent of the blood, and physical activity, with a greater 

 need of food and increased powers of assimilation. 

 "The pupils learn with less effort, better retain the in- 

 formation imparted, and show less and less of the ner- 

 vous strain due to close, heated schoolrooms" (Board 

 of Health, Michigan). These results are universally 

 believed to be mainly due to improved air conditions, 

 and incidentally it may be added that the children 

 require better conditions for body heat removal than 

 adults ; but the better clothing of the body, the better 

 dieting, the midday sleep, and the reduction in mental 

 work, are all contributing factors to the good results 

 obtained. The circumstance that, despite the lighten- 

 ing of the mental work, the scholars do not fall behind 

 the other children in their schooling is noteworthy. 



It may be claimed that experiments have now estab- 

 lished the facts that if the surrounding temperature 

 exceeds 70 F. (W.B.) it is liable to produce discom- 



