PART I.] Cholera and Rainfall m Endemic and N on- Endemic Areas. 265 



taking place in June and the subsequent months, there is unmistakable evidence 

 of its increase, and this continues until the maximum is reached in August — this 

 month furnishing almost twice as many cases as its predecessor and nearly three 

 times as many as September ; there is, therefore, overwhelming evidence to show 

 that, be the actual conditions favourable to the manifestation of the disease what 

 ■they may, they are present to a far greater extent during the month of August 

 in the non-endemic area generally than at any other period of the year. The 

 study of the proportion between the cholera-prevalence of the two areas, when 

 compared month by month, will be simplified by a scrutiny of the accompanying 

 table in which the percentages have been calculated. 



TABLE LII. 



The fact that whereas, taking the whole group of stations in the non-endemic 

 area, 34'2 per cent, of their total cholera occurs in the month of August, only 

 6*5 per cent, occurs in the group illustrative of the endemic area, and still 

 less, 3-8 per cent., in Calcutta when taken by itself during the same month, 

 cannot but arrest the attention of the student. 



(c) Prevalence of Cholera according to Seasons in the Non-endemic Area, and the 



Mean Rainfall for the same Seasons. 



If the principle adopted in a previous chapter of classifying the disease into seasons 

 comparable with the three seasons into which each annual period naturally falls in 

 India be applied to the group of stations in the non-endemic area also, we shall see 

 that the cholera-prevalence in the two areas presents still greater contrasts than was 

 manifested in the classification by months. The following table (LIII), which has 

 been prepared in the same manner as Table XLV (page 249), will enable students to 

 ascertain at a glance what these salient contrasts are. The rainfall has likewise been 

 given here, and the average proportion for each seasonal period calculated out. 



