310 



HUMAN BIOLOGY 



which occurs in storms, but it may be connected with the 

 fact that at very low temperatures moist air feels colder 

 than dry air, although at more moderate^temperatures the 



Rekilive Humuliiy c± 8 AH 



tfO 60 80 



/007. 



Above TO'cdSAH. 



^tl-SO' at 8 AM 

 6l-70'ai SAM 

 51-60' at 8A.M 



Fig. 4. Post-operative Death Rate at Boston in Relation to Humidity and 



Temperature. 

 (From Huntington's Civilization and Climate, ed. 3, Yale Univ. Press.) 



reverse is true. In hot weather the excess of deaths at high 

 humidities represents the discomfort, weakness and ultimate 

 illness which are often the direct result of heat combined 

 with moisture, as in cases of sunstroke. It should be noted 

 however, that even in tropical countries damp heat does 

 less harm than dry heat. Thus in India and similar countries 

 the death rate reaches a maximum during the excessively 

 hot dry weather of the spring months and systematically 

 falls as soon as the rains begin. Part of this is unquestionably 

 due to somewhat lower temperature, but the more favorable 

 conditions of humidity also appear to be important. Never- 

 theless, if the summer air in India should approach satura- 

 tion all the time, which is by no means the case, the conditions 

 would be almost unendurable. The exact state of affairs is 

 illustrated in Figure 4 showing the relative number of 

 deaths following surgical operations performed in Boston 

 hospitals on days with various temperatures and humidities. 

 When the temperature at 8 a.m. is below 70°f., the number 



