CLIMATE AND HEALTH 61 



Let us turn back now to Figure 1. We there saw that with 

 slight exceptions the deathrate in various parts of the United 

 States varies in harmony. We have already seen that variations 

 in the food supply and water supply cannot be the cause of this. 

 Hard times, as we have also seen, are preceded, not followed or 

 accompanied, by a low deathrate. Therefore they cannot be 

 responsible for the uniform fluctuations in health all over the 

 country. Epidemics, as we have just seen, are not competent to 

 cause such great fluctuations. Moreover, as will appear later, 

 they are subject to the same sort of fluctuations as are other 

 diseases, and the cause is apparently the same. This leaves the 

 weather as the only factor capable of producing such marked 

 variations in health over such wide areas. We have just seen 

 that in New York a difference of 7°r in the average temperature 

 of the month of July is accompanied by a difference of nearly 

 30 per cent in the number of deaths. Anyone who reads the daily 

 weather reports knows that extreme weather in Chicago, for 

 example, is almost sure to be followed by similar weather farther 

 east. Thus in the weather we clearly have a factor which not 

 only has an enormous influence upon health and thus upon busi- 

 ness, but which also varies in the same way over vast areas. 



Let us inquire further into the relation of health to the weather. 

 Figure 7 shows how the average daily deathrate of several 

 countries varies from month to month when hundreds of thousands 

 or millions of deaths are considered. Finland, for example, is 

 a country where the summer is never too hot, but where the winters 

 are cold and trying. Notice how the deathrate reaches a maximum 

 in winter and declines steadily to a minimum in summer. Next 

 come curves for the eastern United States from Massachusetts 

 to Washington. This is a region where the winters are cold 

 enough to be harmful, while the summers are hot for at least a 

 short time. In every case the deaths are most numerous in 

 February or March, that is, at the end of the winter. They 

 decline until June, or in the case of Washington until May. Then 



