58 On the Perpetual Snow line, 



decided proof that Captain Webb's doctrine, or at all events the 

 doctrine deduced from his facts, is only locally and not generally 

 applicable. But in support of Dr. Lord's statements we have ob- 

 servations made by other individuals in a part of the Himalaya 

 totally distinct from the other two, and consequently if any general 

 rule is to' be deduced from the observations already made, it must 

 rather tend to show that the snow lies longer on the northern than on 

 the southern aspect, for as yet the evidence preponderates in favour 

 of the northern side. It appears moreover that Mr. Batten in de- 

 fending Captain Webb's statements, has drawn his conclusions from 

 what is observable on the plains of Thibet, rather than from facts 

 apparent on the northern slope of the Himalaya. The question, 

 however, is not whether the snow lies longer on the elevated plains 

 of Thibet than on the sourthern slope of the Himalaya, but whether 

 it does not lie longer on the northern face of those mountains. 

 This point indeed Mr. Batten has already decided, for he says, 

 the northern slope of all the mountains retains the snow longer than 

 the southern side and that this applies equally to hills in Bhote ! 

 That the snow lies longer on the southern slope of the central range 

 than it does on the plains of Thibet to the north of that range, 

 is not disputed, for comparatively little snow falls on those plains, 

 and that little is soon dissipated by the prevailing high winds ; 

 besides which, the sun is very powerful on those tracts during the 

 summer, and it is by no means wonderful under such circumstances, 

 that two feet of snow should take less time to melt on the plains of 

 Thibet, than four or six feet on the more elevated southern slope 

 of the mountains! No great credit is due for such a discovery 

 as this ! 



But Humboldt thought that Captain Webb's observations referred 

 to the northern slope of the mountains, and not to the northern plains, 

 for in his theory of Isothermal lines, supposing from Captain Webb's 

 statements that the northern face of the Himalaya, was more speedily 

 uncovered than the southern face, he endeavours to account for the 

 strange phenomenon by attributing it to the effects of great heat, 

 radiating from the plains of Thibet, thereby clearly proving that it 

 was the mountains and not the plains that were alluded to, by Cap. 

 tain Webb. 



