132 Irregularities of Atmospheric pressure in Bengal, ice. [No. 2, 



May. June. July. Aug. Sept. 



Saugor Island, 82S 38° W 60S 32° W 74S 55° W 77S 47°W 68S 11°W 



Calcutta, 82S 7°W 70S 6°E 84S 5°E 80S 1°E 85S 23°E 



Jessore, 55S 11°E 72S 30°E 82S 18°E 70S 7°E 85S 35°E 



Dacca, 69S31°E 87S 45°E 93S 37°E 90S 9°E 60S 33°E 



Berhampore,.. 63S 43°E 57S 38°E 74S 52°E 64S 23°E 7oS 53°E 



Monghyr, 43N 89°E 63N 86°E 61S 89°E 22S 75 E 63S 84°E 



Patna, 84N 7°W 92N 3°W 71N 6°E 72S 29°E 



Benares, 58N 5°W37N41°E 27 E 14N 48°\V 56N 8°E 



Gya, ? 23S 84°E 42S 77°E 22S 1°E 7lS 78°E 



Hazaribaugh, 32S 27°W 40S 15°W 32S 18°E 32S 19°W 61S 42°E 



To sum up the principal facts brought out in the foregoing dis- 

 cussion. 



In the monsoon seasons both of 1868 and 1869, there was an 

 area in or on the borders of Lower Bengal, in which the atmos- 

 pheric pressure was persistently low, and which was partially or 

 entirely encircled by a region of relatively high barometer. It 

 originated with the general redistribution of barometric pressure at 

 the beginning of the S. W. monsoon in April, and became intensified 

 with the first fall of the rains in June. In 1868 it retained its initial 

 position with a slight variation throughout the monsoon season, the 

 depression being most intense in June and August, after which latter 

 month it gradually decreased in intensity, but did not disappear 

 till December. In 1869 it contracted or retreated northward and 

 as far as can be judged did not entirely disappear, although its 

 influence was diminished until quite the end of the monsoon. Its 

 position was different in the two years, being in the former in the 

 N. W. corner of the Bay of Bengal, in the latter in the hilly 

 country to the west of the delta. 



It influenced the vapour bearing winds from the south by deflec- 

 ting them towards it, and necessarily by determining an ascending 

 current, it produced an excessive rainfall to the north of its position, 

 the maximum fall being at from 50 to 150 miles from the place at 

 which the barometer was lowest. Finally it impeded the passage of 

 the vapour-bearing winds to the N. W. Provinces, and thus deprived 

 that region of a great part of its usual annual supply. 



