252 On the Normal Rainfall of Bengal* L^" 0, ^> 



weeks later. The focus of heat, as Col. Strachey long since obser- 

 ved, and as is shewn in the Messrs. Schlagintweit's charts, is 

 now transferred to thePunjaub, and the air from the Bay of Bengal 

 is drawn across the hilly region of Western Bengal and Orissa, and 

 up the Gangetic plain as a SE, ESE or easterly wind. The 

 mean annual fall decreases gradually ceteris paribus with the in- 

 creasing distance from the Bay of Bengal. At Benares, the mean 

 fall is 34.34, at Agra 25.17 inches &c. As I have pointed out in a 

 previous paper, the immediate cause of the deficient rainfall of the 

 N. W. Provinces in 1868 and 1869, was the existence of a 

 circumscribed area of low pressure, immediately in the path of 

 their winds, and their consequent detraction from their usual path. 

 The monsoon of Hindustan is, therefore, a local phenomenon, 

 independent of that of Central Asia or nearly so, while the 

 SW monsoon of Eastern Bengal is probably a part of the greater 

 movement which has its centre in the latter region. The focus 

 towards which the monsoon of Hindustan flows, is the heated and 

 dry region of the Punjab, which is the limit of the rains, and where 

 they are comparatively light, not exceeding five inches in the five 

 months, from June to October, at Mooltan.* 



The monsoon of Bengal usually lasts to the first or second week 

 in October, but northerly winds frequently begin to be felt some- 

 what earlier ; the plains of Northern India being now cooled down 

 by evaporation, while the sun is retreating in Southern declination, 



Meanwhile the Southern part of the Coromandel Coast and its 

 adjacent plains have received little or no rain, since, as is well 

 known, the SW monsoon is nearly exhausted of its moisture 

 by the Ghats and Table land of Mysore, and the still loftier 

 hill-masses to the South that lie along the west coast, and form 

 an interrupted prolongation of the Ghats. When, therefore, the 

 air is no longer drawn from the south towards Northern India, 

 the plains of Madras still retain a high temperature and as 



* The mean of the five years, 1S62-66 at Mooltan is given by Dr. Neil, the 

 Meteorological Reporter for the Punjab, as follows : — 



June, CNO 



July, 1-76 



August, 1-74 



September, 0'50 



October, 0*50 



