308 Journal of the Asiatic Society of Bengal. [ Aug.-Sept., 1913. 
Gangetic plain, and this emphasizing of the cyclonic movement 
gives rise to ‘‘ thunderstorms’’ over the whole of Bengal. 
Nor’westers, he records, occasionally pass seawards, but die 
out not far from land and are therefore only occasionally felt 
on Saugor Island itself. 
THe TypicaL Nor’ WESTER. 
preceding section I have dealt with already 
recorded facts and theories. It is necessary now to consider 
more intimately the individual structure of the nor’ wester. Its 
distinctive features are its rapidity of approach and the rapid 
transverse motion of the clouds in addition to the forward 
movement. The storm, in its most typical form, is first seen 
as a big bank of vapour on the north-western horizon. Its 
ing briskly towards it from the south and south-east. As the 
cloud comes nearer it is seen that in addition to the centre 
core of cloud moving towards the spectator there is a bank of 
somewhat lower cloud also moving forward but having in ad- 
dition a very rapid transverse motion from west to east, or the 
same direction in which the winds revolve in the big cyclonic 
storm systems. Just before this cloud arrives overhead 
appears to rise. But this may be only the effect of the dying 
away of the wind. I have not tested the matter. Under the 
there is a rotary or churning motion or sometimes even & 
rapid motion from the south to north towards the second 
wave. ith the second wave comes a temporary increase of 
the wind which has been continuing to blow from the north- 
west. But the main feature of the second wave is the heavy 
clear up almost completely. As regards the lightning which 
accompanies the storm, it is associated with all three phases, 
but is mainly confined to the second wave and the subsequent 
p : 
This then is the typical storm. But by no means all nor’- 
westers follow it exactly. In many cases there is only one 
transverse-moving wave. In other cases the cloud does not 
clear up after an hour or more of rain. The rain continues to 
fall, but less furiously, and a great deal of lightning takes place 
