1908.] 0. Little — Himalayan summer storms. 239 



men was in white granular cakes, and the second contained in addition 

 masses of white silky crystals. On analysing the soluble portion of each 

 it was proved that the mineral was Alunogen or " Hair Salt," with a 

 composition of : Alumina 153, sulphuric acid 36 and water 48*7 per cent. 

 This composition agrees with the formula of Alunogen, viz., Al 2 O g 3 S0 3 , 

 18 HgO. 



Himalayan summer storms and their influence on monsoon rainfall in 

 Northern India. — By 0. Little, M.A. 



In a paper which I read at the April meeting of this Society I 

 pointed out that the monsoon season of 1902 could be divided into four 

 periods, in each of which the character of the season as regards the 

 distribution of rainfall and the movement of cyclonic storms which 

 entered India from the Bay of Bengal were noticeably different. I gave 

 a number of tabular statements showing that important changes appear- 

 ed in the Himalayan region about the 30th of June and tlie 11th of 

 August, that these changes did not begin over India, and that there was 

 abundant reason for the belief that they approached India from Central 

 Asia, that is, from an easterly or north-easterly direction. I gave the 

 paper the title of " Two remarkable rainbursts in Bengal," because the 

 unexpected occurrence of heavy rainfall in north-eastern India attracted 

 my attention and led to the subsequent investigation. 



Although the present monsoon season is not yet half over, there 

 have, in my opinion, been already no fewer than three occasions on which 

 the weather in Northern India has been influenced by similar 

 disturbances, that is, by disturbances which have made their first ap- 

 pearance in the region of the Himalaj^as. I have called them Himalayan 

 storms because they come within our range of observation when they 

 reach the hills ; but the probability is that they are due to depressions 

 moving across Central Asia. Their appearance begins with an irregular 

 fall of the barometer at stations in Northern India, and an indraught of 

 winds in that direction : after a longer or shorter period pressure begins 

 to rise, and this rise of pressure is accompanied by the commencement 

 of rainfall, not I believe rainfall of the monsoon type, but the irregularly 

 distributed, and often heavy rainfall caused by numerous thunder- 

 storms. 



J. ii. 33 



