1856.] Report of the Magnetic Survey of India. 113 



Thibet. During the time of heavy rain-falls on the southern side 

 of the Himalayas, we very often saw for several days together 

 masses of clouds, which came from the south, hanging over the 

 Sutlej plain. They occasionally produced rains, which fell in great 

 quantities, but never lasted an entire day. 



6th. The winds in the Himalayas and in Thibet during the 

 summer months, are generally of great regularity, blowing up con- 

 stantly nearly every day from the South, South- West or South- 

 East. 



(a.) In the upper Himalaya valleys, the wind generally sets in 

 at from 9 hours to 10 hours a. m., its strength increasing consider- 

 ably towards the evening. 



(b.) The intensity of the wind seems to be greatest on the passes 

 leading from Thibet into the Himalayas elevated from 17,000 to 

 19,000 E. E. where we experienced sometimes in the afternoon a 

 most furious Southerly gale. In going from thence to the South- 

 ward, the intensity of the wind decreases in a very striking way, 

 and on Kedar Kanta, and on the stations in the outer Himalayan 

 ranges, the intensity of the wind is, comparatively speaking, very 

 slight. This increase in the intensity of the wind on the high 

 northern passes seems to be due to two causes — the first of them is, 

 that the wind may in part originate in the hot valleys of the South- 

 ern Himalayas themselves ; the second, and we presume the more 

 important cause, will be that the wind produced by the great ascend- 

 ing current over the heated Indian plains is fast travelling North- 

 ward at a very great elevation, and only sinks down when it reaches 

 the colder and higher chains of the central Himalayas. 



In support of the latter view, we may mention that we often saw 

 very high clouds above us moving at a great rate, whilst the wind 

 at our own elevation had a much smaller velocity. 



7th. Our observations of the temperature of springs and of the 

 ground at various depths have shown — 



(a.) That the temperature of springs and the temperature of 

 the ground at depths varying from one to three meters, is, at equal 

 heights, considerably higher in Thibet than in the Himalayas ; the 

 cause of this will be that, in Thibet, we have a plateau whose mean 

 elevation is from 14,500 to 16,000 E. E., whilst the Himalayas, at 



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