OF ATMOSPHEIilC CHANGES UPON DISEASE. 167 



when contiimous, causing a rapid increase in the 

 number of cases. 

 A temperature below 60° appears to be unfavourable to its 

 progress. 



The above action is generally most evidently shown 

 when the temperature is above or below the average of the 

 season. 



In the spring of 18^7, from April 11th to June 20th, 

 there is a gradual, and at first scarcely perceptible, rise in 

 the diarrhoea curve, the number of cases being compara- 

 tively very small. 



The temperature in April and the early part of May is 

 much below the average (8° on May 2nd), although, on 

 the whole, gradually rising. 



From June 20th to July 11th the rise of the disease 

 curve to 2,000 cases is more rapid — the temperature is 

 above 60°, and on June 2yth y° above the average. 



From July iSth to August i^th there is a very great 

 increase in the number of cases (even to 5,600), but from 

 the latter date until September 12th the curve sinks at 

 nearly the same rate to 2,200 cases. 



The number of cases then continues to diminish, but at 

 a rather slower rate, until October 10th, when it is 600. 



The mean temperature during the ivhole of this period, 

 from July I'^th to October 10th is above 60°, and con- 

 siderably above the average, sometimes as much as 7°. In 

 the weeks ending July I'^th and 2Qth, it is stationary at 

 68° (the highest point this year), but it then gradually 

 falls to 63*5° on August i^th; and after a temporary rise 

 in the week ending August 29^^ it continues to fall until 

 October 10th, thus throughout bearing a close relation to 

 the disease. 



From the week ending October xoth (the temperature 

 being \'g° below the average) the number of cases still 



