1873.] H. F. Blanford— On tie Climate of Bengal. 181 



almost to an equality with that of the maritime region. This is clearly 

 traceable to the winds ; since, in the former region, winds from the sea predo- 

 minate throughout the hot season, mitigating its temperature indeed, but 

 at the same time rendering the atmosphere damper ; and producing, when 

 the air is calm, that oppressive feeling of sultriness, which is so trying to 

 persons accustomed to the drier atmosphere of Bihar and the North- West. 



The relative humidity of air or its nearness to saturation depends on 

 the temperature as well as on the absolute cpiantity of vapour it contains. 

 If the latter be constant, the air, as is well known, is drier with a high tem- 

 perature than a low one. Thus arises, in the cold weather months, the 

 apparent anomaly that, although the absolute humidity of Upper India at 

 that season is considerably less than that of Bengal, its relative humidity 

 does not undergo a corresponding diminution, owing to its lower tempera- 

 ture. At Banaras for instance and even at Labor, as appears from the 

 Panjab reports, the relative humidity of the air in January and February 

 exceeds that of Dhaka and Barhampur. In this sens3 the driest period of 

 the year falls later and later in the spring months as we proceed inland. 

 At Sagar Island, January is the driest month ; at Calcutta, February and 

 March ; at Patna, April ; at Banaras, April and May ; while at Lahor and all 

 places in the Panjab, May and June are the months of greatest siccity. 

 The frequency of rain depends on relative rather than absolute humidity ; 

 the quantity of rain that falls, other things being equal, chiefly on the abso- 

 lute humidity of the air. 



Eastern Bengal, including Kachar and Silhet, and the Himalayan Tarai, 

 are the districts of the heaviest rainfall. Their average annual fall almost 

 every where amounts to 100 inches ; and on the exposed hill flanks, and at 

 their foot, even this large amount is greatly surpassed. Thus Silhet has an 

 annual average of 141 inches. Darjiling 126 inches, the Rangbi Cinchona 

 plantation 175 inches, Buxa Fort 280 inches, (the average of three years,) 

 and Cherra Punji the enormous amount of 527 inches ; this last is the high- 

 est average rainfall hitherto recorded in the world. The rainfall is also 

 higher on the plains of the coast than on those lying more inland. Thus 

 Sagar Point has an average of 87 inches and Calcutta 6(3, False Point 74 

 inches and Katak 52'5. The lowest rainfall in the provinces under the 

 Bengal Government is that of the Southern portion of Bihar, including 

 Monghyr, Gya and Patna, where the annual fall does not much exceed 40 

 inches ; and in the case of the last mentioned station is only 37 inches. North 

 of the Ganges, it increases gradually up to the Himalaya ; and, on the south, 

 up to the high ridge of forest-clad country which is drained by the Son, 

 the Damudar and their tributaries. In this tract, where the monsoon 

 winds from the opposite coasts of India meet, the fall of the few stations 

 that have hitherto furnished registers, ranges between 50 and 60 inches. In 



