114 Report of the Magnetic Survey of India. [No. 2. 



the same height, offer only a series of ridges, intersected in a} 

 directions by large and deep valleys. 



(b.) The height at which the temperature of the ground is 0° 

 cent, or 32° Faht. seems to be along the passes which lead from the 

 Himalayas, into Thibet, about 17,000 F. F., at this height we several 

 times found the temperature of the ground at a depth of 2 or 3 

 meters to be 0° cent., and some good springs a little lower showed 

 temperatures of only 0.2° and 0.5° cent. 



8th. In the outer ranges of the Himalayas, and in the valleys 

 between them, at elevations of about 4,000 E. F., the temperature 

 of good springs on an average may be assumed at 18° cent., the 

 decrease of temperature from this height to the line of zero would 

 therefore be one degree cent, for an ascent of about 720 E. F # 

 It seems pretty certain that the decrease of the temperature of the 

 ground and of the springs from the foot of the Himalayas up to 

 the line of zero is more rapid than in the Alps of Europe, where we 

 formerly found 700 or 730 French feet for a decrease of temper- 

 ature of one degree cent. 



9th. We endeavoured as often as possible throughout the journey 

 to determine the height of the different lines of vegetation, the height 

 of the snow line, &c, by aid of our barometers. We found, as a 

 general rule, that the limits of shrub vegetation, of grass, and phane- 

 rogamic plants, rise considerably higher on the Thibetan Mountains 

 than in the Himalayas. We found that some very isolated phane- 

 rogamic plants ascend generally speaking, in these two Mountain 

 ranges to heights of 17,800 to 18,400 E. F. ; the maximum of height, 

 to which we saw some very few phanerogamic plants rising, was on 

 a sunny rocky island, between the snow masses of the Ibi Gamin 

 glacier, at an elevation of 19,800 E. F., which, if we are not mis- 

 taken, is the greatest height at which till now phanerogamic plants 

 have any where been found. The line of the lower limit of snow 

 without doubt rises higher on the Northern Thibetan side of 

 the Himalayas than on the Southern India face of the mountains, as 

 Humboldt maintained a long time ago. 



In reference to the periodical development of vegetation, which 

 forms an interesting element in considering the Physical Geography 

 of a country, we may mention, amongst other results, that in Thibet, 



