0. Litfcle — TJie recent excessive heat in Bengal. [No. I, 



indicate an exceptional condition of the upper air, a condition which may- 

 have, and which I believe, had an important influence on the temperature 

 in Bengal. 



In ordinary years, I believe, the main upper current as it flows over 

 the south-western districts of this Province in the hot season is from 

 the north-west. The chief item of evidence in favour of that is the po- 

 pular term " nor' wester." These thunderstorms drift with the upper 

 current, and their line of advance is therefore the direction of the wind 

 aloft. One or two other items of information could be given in support 

 of this upper north-westerly wind. Calcutta residents may remember 

 Spencer's balloon ascent from the neighbourhood of tbe race-stand some 

 years ago, about the beginning of the hot season, and how the balloon dis- 

 appeared at what was probably a great height, moving in a south-east- 

 erly direction. I have occasionally sent up small hydrogen balloons about 

 three feet in diameter and have watched them through opera glasses 

 until they disappeared. The direction of their motion was the same as 

 that of Spencer's balloon, and of the thunderstorms, that is to the south- 

 east. I think it likely that a continued series of observations for a num- 

 ber of years would have established as a fact that generally a north- 

 westerly wind continues throughout the greater part of the hot season 

 in this part of India at a height of 10,000 to 20,000 feet. 



The past year has, in my opinion, been exceptional as regards the 

 direction of the upper wind. All the observations I have made (and 

 I have watched every storm which has passed over Calcutta, and the 

 cloud movement whenever cloud existed) have shown that, throughout 

 the season, from the 23rd of February when the first thunderstorm oc- 

 curred until the middle of June, the wind instead of being north-westerly 

 has been from a direction almost due west. The cloud movement, so far as 

 I have been able to fix it without instrumental aid, has been from the 

 west. This cloud motion was steady and probably of considerable amount 

 daring the early part of the season, and it became feeble and intermit- 

 tent after the middle of May. Nothing is known as to the height of the 

 light cumulus cloud occasionally visible in the hot season. Its motion 

 shews that at that particular height the air is moving from the west, but 

 whether that westerly air-current extends much higher than the cloud or 

 begins much lower can be only a matter of surmise. 



Thunderstorms, however, give some additional information. The 

 drift of a thunder cloud, which extends from about 4,000 feet above the 

 earth's surface to something like 30,000 feet, cannot be determined by 

 an air-current which is not one of great depth, and the thunderstorms of 

 the past season have throughout confirmed the cloud observations. 



The most important observation which I wish to record is that the 



