1870.] 123 



On certain protracted irregularities oe Atmospheric pressure 

 in Bengal in relation to the Monsoon rainfall oe 1868 and 

 1869, —by Henry F. Blanford, Meteorological Reporter to 

 the Government of Bengal. 



(With plate VIII.) 



[Eeceived 17th February, 1870. Read 2nd March, 1870.] 



When the Meteorological system, recently established in Bengal, 

 began to afford trustworthy results, one of the first objects of 

 enquiry that engaged my attention, was the variation of the 

 monsoon rains. The year 1868 was marked by a rainfall in Lower 

 Bengal (more especially at Calcutta and the S. Western part of the 

 Gangetic delta) of almost unprecedented amount, while in the N. 

 W. Provinces and the Panjab, the deficiency was such as to cause 

 a very considerable failure of the crops and much consequent 

 suffering. This year (1869), the rains have been comparatively 

 light throughout Northern India, including Bengal, except in the 

 districts to the North of the Pudma* river ; and it is fresh in the 

 recollection of all residents in Northern India, that large tracts in the 

 N. W. Provinces, Central India and the Panjab, have been pre- 

 served from the imminent horrors of famine only by the timely 

 rains at the very close of the ordinary monsoon season. My object, 

 in the present communication, is to bring to notice certain peculi- 

 arities in the distribution of the barometric pressure, which seem to 

 throw some light on the causes, the proximate causes at least, of 

 these notable and important variations. 



In watching the daily and monthly reports received from the 

 Meteorological stations in Bengal, I early observed that sometimes 

 for periods of several months, the barometric readings at certain 

 stations, when reduced to the sea-level, shewed an apparently 

 anomalous depression or elevation ; anomalous, that is to say, as 

 not conforming to the general law of the barometric gradient for 

 the time of year, as then known. I was at first inclined to suspect 

 that the assigned elevation of certain of the stations might be erro- 

 neous, or that, possibly, the barometric registers might be vitiated 



* The name given to the main stream of the Ganges below Rajmahal. 



