36 H. F. Blanford — On protracted Relative [No. I, 



If then, as I cannot but conclude, the distribution of pressure in India 

 is subject to protracted local variations, which nevertheless are not perma- 

 nent, it seems probable that we may find herein a clue to the explanation 

 of those irregularities of the rainfall that have so important an influence 

 on the welfare of the people ; and the connection between the two classes 

 of phenomena must become a question of very high practical as well as 

 scientific importance. 



I have already shewn reasons why this enquiry cannot be satisfactorily 

 undertaken at present. For instance, the establishment of an observatory 

 at the Nicobars in May 1873, brought to light the apparent existence of a 

 remarkable barometric depression in that neighbourhood, of which we 

 should otherwise have remained in ignorance. What its extent may have 

 been, we do not know, but its position is such that it must have been in- 

 fluential in drawing aside a portion of the monsoon current which otherwise 

 would pass up the Bay towards Northern India. So long as we remain 

 without information of the meteorological conditions in any part of the 

 Indian monsoon area, we cannot be sure that the effects we witness in Nor- 

 thern India may not have resulted from causes whose seat lies without our 

 area. 



But although any comprehensive discussion of the subject is impossi- 

 ble, I may point to some observed relations between barometric depression 

 and rainfall which are, I think, too striking to be a fortuitous coincidence. I 

 refer more especially to the excessively heavy rainfall which occurred in the 

 region of which the town of Hughli is the centre, in August 1868 ; when 

 a very intense depression lay near Saugor Point (100 miles to the south) 

 off the mouth of the Hughli. In the previous month of June, when the 

 site of the minimum pressure was in the neighbourhood of False Point, the 

 region of excessive rainfall lay about Balasore and Contai (100 miles to the 

 north), and throughout the season, while the barometric depression held its 

 place in the N. W. corner of the Bay, the excessive rainfall was restricted to 

 the south-west corner of the Grangetic delta, although the fall was heavy 

 over a considerable part of the delta. In Behar on the other hand, and in 



fixed in position by myself, and a second series of simultaneous readings for a month, 

 gave, after due correction, the same results. The instrument had been moved to a differ- 

 ent house, I believe in 1870 ; but a line of levels taken at my request by the Executive 

 Engineer of the station shewed that the two positions of the instrument were apprecia- 

 bly at the same level. The Saugor Island barometer which in 1868 shewed as great 

 a fall below the usual pressure as that of False Point, has been compared three times, 

 viz. when first supplied to the station, again by myself on the spot at the end of 1870, 

 and lastly with a Casella's standard supplied to the station in 1873. The results of 

 these comparisons agreed accurately, and the instrument has always been in the 

 same position. 



