1870.] On the Normal Rainfall of Bengal. 245 



groups, which lie terms respectively the Dacca Group and that of 

 the Ganges plain and the Himalaya, This division is in so far 

 natural, that the stations of the former group, lying to the east 

 of the Bay and the Gangetic delta, receive their rain from the SW 

 winds, which, passing over the Bay of Bengal, reach them without 

 much alteration of direction, and at an earlier period of the year, 

 while the temperature of the Peninsular and the Ganges valley 

 is rapidly rising under the rays of a vertical sun. The westerly sta- 

 tions of the latter group are visited by heavy rainfall, only when, in 

 consequence of the high temperature of May and the early part of 

 June, and consequent fall of the Barometer, a large body of the 

 saturated air from the Bay is drawn round from its primitive 

 direction towards the plains of Upper India, which it reaches at a 

 SE or ESE wind. The rainfall, therefore, commences and reaches 

 its maximum at a later period at these stations. 



Mr. Dove's tables give the rainfall of 12 stations only. The 

 larger number of the stations for which I now have registers, per- 

 mits of a more detailed grouping, and I am enabled to classify 

 them with regard both to their exposure and elevation, as well as 

 to the comparative siccity or moisture of the rain-bearing currents, 

 that reach them. This is determined chiefly by the nature of the 

 country traversed by these winds in their passage from the Bay of 

 Bengal. The arrangement adopted is the following — 



f 1. Assam Group. j Seebsaugor, Tezpore, Nowgong, 



r { b-ownatty, Goalpara. 



2. Khasi Hills. Shillong, Oherrapunji. 



""£ ^ 3. Silhet Group. Silhet, Cachar. 

 £} | 4. Tipperah and Ara- ( Tipperah, Noacally, Chittagong, Ak- 



^ kan Group. ( yab, Sandoway. 



^ 5 Delta Group { Jessore, Calcutta, Kishnagur, Moor- 



_; j ^' \ shedabad,(Berhampore), Burdwan. 



J ! ( Dacca, Mymensing, Bogra, Kung- 



C i fi "NTrvr+.Ti «-rn Orrm-n / -nor A T")infn'nrrrA lVTfl1rl«Ti T?,fliimarfi 



1 



3 



g I 6. Northern Group. } pore, Dinajpore, Maldah, Eampore 

 O j ( Beauliah. 



^7. Himalaya. Darjiling, Eungbee. 



f« BeharGrouD ( Monghyr, Gyah, Patna, Tirhoot, 



tfenar brroup. ^ Chuprah, Arrah, Chumparun. 



( Bhagulpore, Soory, Ranigunj, Ban- 

 ^ 9. Western Bengal. < coorah, Midnapore, Manbhoom, 



( Hazareebaugh, Ranchee. 



,~ r\ - n ( Balasore, Cuttack, Pooree, Sumbul- 



10. Orissa Group. j ^ ' 



