128 Notes on Central Asia. [No. 3, 



But Humboldt could not have taken exception to the method used 

 in measuring the height of the snow-line, in the Tian-Shan, because 

 he at that time did not know what means were used for this purpose, 

 and also because he himself adopted the same method on his journey- 

 in the New World, which was so prolific of scientific results. Hum- 

 boldt's doubts respecting the probability of the height of the Tian- 

 Shan snow-line (as fixed by me), being considerable, were based on 

 considerations of comparative geography, and their soundness or other- 

 wise may be easily tested, for they were founded on a comparison 

 of their height of snow-line, 11,000 to 11,500 feet, with its well 

 ascertained limits in nearly the same meridian (in the Altai, 6,600 

 feet) or in the same parallel, (the Pyrennees, 8,400 feet and the 

 Caucasus, 10,170 feet). 



In examining the observations made by any traveller respecting 

 the elevations of the snow-line, the most accurate scientific criticism 

 must test their correctness, by the following theoretical investiga- 

 tions. 



The height of the snow-line in a given range, must be calculated 

 theoretically on the basis of a comparison with other ranges, on the 

 same meridian, and the same parallel ; the obtained results should 

 then be compared with the figures arrived at by actual observation, 

 and it must then be carefully considered whether the discrepancy that 

 may occur can be at all attributed to considerations of climate, and 

 local peculiarities. 



Humboldt, in his classical work " Asie Centrale," supplies us with 

 the requisite figures for arriving at a definite conclusion. 



In the same meridian with the Celestial mountains we find that the 

 height of the snow-line is as follows, 



In the Altai (Tigerski Belki) 



Lat. 51° North, 6,600 feet. 



On the Northern slope of the Himalayan range, 



Lat. 32° North, 15,600 feet. 



The Celestial mountains extend at the part visited by me, between 

 Lat. 41° and 42° North which is consequently mid-way between the 

 Altai and Himalayas. Taking the mean of the figures given above 

 we shall get 11,100 feet for the height of the snow-line of the Celestial 



