6 CLIMATE AND KESOURCES OF 



during the night, and its superincumbent air has also become 

 cooled, the air from that direction will, from its greater 

 gravity, rush towards the east, and displace that which has 

 become heated and is lighter; and thus we have west winds. 



In a former paragraph, alluding to the general opinion that 

 east winds in Upper India bring clouds, I said it seemed 

 doubtful whether the clouds were the effect or the cause of 

 the east winds. It appears to me highly probable that clouds 

 caused by some meteorological disturbance having prevented 

 the falling of the sun's rays on the soil, and hindered its 

 becoming heated, have thus diminished the causes giving rise 

 to the west winds, and we have, in consequence, a restoration 

 of the normal north-east trade-winds. This seems the more 

 probable, as, when a hailstorm or fall of rain occurs during 

 the season of the hot winds, over a considerable tract of 

 country, during the time the land is wet, and while there is 

 great evaporation from the surface, we have east winds. In 

 this case the vapour in the air, from evaporation, arrests the 

 rays of the sun, and the surface is cooled by evaporation going 

 on upon it. Thus it appears that while the causes producing 

 the west winds, the chief of which I consider to be the heat- 

 ing of the surface, are in abeyance, the normal north-east 

 trade- winds resume their sway. During the hot weather the 

 thermometer often rises during the day to from 120 to 130 

 Fahrenheit in the shade, and all nature suffers. All wood- 

 work exposed to the dry, hot air warps and splits, and 

 speedily goes to rack and ruin. 



It is generally acknowledged that the heat of Upper India 

 has very much increased of late years, and various facts seem 

 to show that such is the case. Early in the present century 

 it was considered by the English residents in India unhealthy 

 to use punkahs at night, and many did not do so. Now their 

 use at night is universal. 



