1881.] 



on the Weather and Health of London. 



633 



of colder weather. The curves for dysentery, British cholera, and 

 cholera are substantially the same as the curve for diarrhcca, and all 

 show the same close obedience to temperature. It is a noteworthy 

 circumstance that these four curves group themselves into pairs — 

 diarrho3a and British cholera on the one side, and dysentery and 

 Asiatic cholera on the other. The chief points of difference are that 



Jan. 



100 



Mean 



Feb. 

 I I I 



J-L 



March, 

 I I I I 



iJ. 



April 

 f I I 



May. 

 I I I 



Fig. 5. 



June. 

 I 1 I 



! I I I I I I I I I I I I 1 ! I ' Ml ' 1 ■''''■'" ■ 



Diarrhoea. 



dysentery and Asiatic cholera begin markedly to rise considerably 

 later than the other two allied diseases, attain their maximum a 

 month later, and fall more rapidly than they rose, the annual phases 

 being nearly a month later than those of diarrhoea and British 

 cholera, which diseases are less deeply seated in the system. 



The peculiarly malignant character of summer diarrhoea among 

 young children under five years of age may be shown by the weekly 

 mortality from diarrhoea, rising from 20 in the middle of June, to 342 

 in the first week of August, 1880, when the mean temperature of July 

 and August was about the average. In July 1876, when the tempera- 

 ture was 3° • 6 above the average, the weekly mortality from diarrhoea 

 among children rose to 502 on the last week of that month. On the 



