PART I.] Season Characteristics of Cholera-prevalence in Calctitta. 



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and in which therefore its influence on soil-ventilation is also uniformly distributed. 

 Enough has, however, been shown here to prove that, in tropical climates at all events, 

 the influence of rain on health cannot be regarded as necessarily solely exerted through 

 such channels. 



CHAPTER III. 



PHYSICAL CHARACTERISTICS OF THE DIFFERENT SEASONS OF CHOLERA-PREVALENCE IN 



CALCUTTA. 



It has been already pointed out that the year may be divided into three seasons, 

 according to the degree of cholera-prevalence. During one of these seasons the preva- 

 lence greatly exceeds the average, during another it falls far short of it, and during 

 the third it ranges on either side of it. The season of maximum prevalence includes 

 the months of February, March, April and May; that of minimum prevalence, the 

 months of July, August and September ; and that of medium prevalence, the 

 remaining five months of the year. In order to facilitate the comparison of the main 

 meteorological characters of these three seasons, it will be well at first to leave two of 

 the months of the season of medium prevalence out of consideration. These are June 

 and October, when the conditions are greatly complicated by the transitional character 

 of the months as periods ushering in and concluding the rainy season, June partaking 

 of the characters of the hot and rainy seasons, and October of those of the rainy and 

 dry ones. Leaving them out, we find the meteorological characters of the individual 

 cholera seasons to be the following : — 



TABLE XXXVII. 



Fhysical characteristics of the individual months of the seasons of maximuni, 

 minimum and medium Cholera-prevalence in Calcutta. 



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