23 H. F. Blanford— On protracted Relative [No. 1, 



the distribution of relative pressures during the SW monsoon deviates 

 somewhat from the normal or average type in certain years, the variations 

 which appear at the beginning of the season in April or May are almost, if 

 not quite, as persistent as the normal features of distribution shewn in the 

 charts ; and sometimes, indeed, last through one or two years. Tbis fact is 

 one which may prove hereafter of much practical importance. Since the 

 strength and direction of the winds are determined by differences of pres- 

 sure in neighbouring regions, and since the monsoon rains are in their turn 

 dependent on the vapour-bearing winds, it might be expected that the ano- 

 malies of rainfall would also shew a certain persistence, and that each sea- 

 son, and, in certain cases, two seasons in succession, would preserve much the 

 same character in regard to the excess or deficiency of rainfall. As far as 

 observation hitherto has afforded the means of testing this presumption, this 

 appears to be actually the case ; the result being sometimes a succession of 

 destructive floods, at other times the failure of the late autumn crops over 

 large areas, producing those famines for which India is disastrously noto- 

 rious. 



Until about eight years ago there were no systematic records of meteo- 

 rological phenomena in India, sufficiently general for instituting an enquiry 

 into a question of this kind : and even up to last year, those that are trust- 

 worthy and at the same time accessible, related only to about a third of the 

 wbole area of India. It is therefore for this portion only that evidence is 

 at present forthcoming. But fortunately this includes the greater part of 

 the area which is concerned with tbat branch of the monsoon that traverses 

 the Bay of Bengal in the summer months ; the remainder being chiefly 

 watered either by the current which proceeds from the western coast ; or, 

 in the case of the Carnatic, by the Bay of Bengal current which is deflected 

 towards that region in October and November. 



"With such partial data as have hitherto been available, it is certainly 

 not possible to establish definite laws of the relations between the quantity 

 and distribution of the rainfall on the one hand, and local irregularities in 

 the distribution of pressure on the other. To do this effectually will re- 

 quire much more complete data than we at present possess ; including a 

 knowledge of tbe distribution of atmospheric pressure over the whole of 

 India and the neighbouring seas ;* and more perfect means of determining 

 the absolute movement of the air,f its temperature and humidity, than are 

 at present available. I shall therefore content myself in this place with 



* This, it is hoped, -will be shewn for the first time in the Report on the Meteorology 

 of India for 1875, by means of isobaric and wind-charts for each month of the year. 



f Steps have been taken to procure self-recording anemometers for this purpose, 

 which will be erected at some 20 stations in addition to the three presidency capitals ; 

 which are already provided with them. 



