PART I.] Mean Monthly Physical Conditions at Calcutta and Lahore. 285 



ENDEMIC AREA. 

 (CALCUTTA ) 



NON-ENDEMIC AREA. 

 (LAHORE.) 



Atmospheric pressure 



Temperature °F. 



August-Rainfall = 13"-71 ■' 



March-Cholera = 18-C per 

 cent, of total. 



August-Humidity = 88 

 degrees. 



lEGKriTzaisai 



■g^BliaaCBStBlHIl 



■EH ^nBaEmnQBii 





■■^■i^aiicnixzsnanBMH 



BBS 



■UUISidUkVI 



IKEH 







Atmospheric pressure. 



Temperature ?F. 



Julj-Bainfall =: 6"-29. 



August-Cholera = 75'2 

 per cent, of total. 



January-Humidity = 57 

 degrees. 



Diagrams 10 and 20. — Illu.strative of the mean monthly Physical Conditions and the prevalence of Cholera 

 in the Endemic and Non-Endemic areas — Calcutta and Lahore. (The Calcutta Cholera-curve has 

 been cut a space too high throughout in the diagram.) 



Taking these stations as affording indices of the general characters of the areas 

 in which they lie, we find certain marked apparent contrasts between them in regard 

 to the conditions coincident with maximum and minimum prevalence. Maximum 

 prevalence in Calcutta occurs coincidently with relatively high atmospheric pressure 

 and with low humidity and rainfall : whilst in Lahore it is associated with precisely 

 the opposite conditions. 



The data in the Bengal Presidency afford no ground for supposing that 

 atmospheric pressure exerts per se any appreciable influence on prevalence ; and the 

 contrasts presented by the endemic and non-endemic areas in this respect must be 

 regarded as entirely subordinate to those of relative humidity and rainfall. 



With reference to atmospheric temperature in place of contrast there is agree- 

 ment, and it is corroborative of belief in the actual existence of an influence of 

 temperature on cholera-prevalence to find, that viery much in proportion to the 

 increase in the difference between the temperature of the various seasons there is 

 a corresponding increase in the difference of prevalence occurring in them.* In 



* It will be observed that no special notice has been taken of the question of range of temperature, as 

 a characteristic of the various seasons. This is not the result of an omission, but as the only thing that 



20 



