1866.] Tableau of High Asia. 59 
the highest, remain open throughout the year. In some parts of 
Tibet the winter is the only season, when atmospheric precipitation 
at all takes place. 
In the Kiinliin, even on its southern slopes, a greater amount of 
snow is precipitated than en the northern side of the Karakortim, 
whilst its Turkistani (northern) slopes differ still more from the 
Karakorém in this respect, they being visited by very heavy rains and 
great snow-falls. Even at Kashgar (about 3,500 ft), in Turkistén, 
there are said to be several snowy days every winter. 
The data, which I was able to collect on snow-fall in the Andes, are 
so few and vague, that I could not draw any conclusion from them. 
Also for the Alps, I could not bring forward any new facts with 
reference to the snow-fall. 
2. Snow-line. 
The snow-line, or the average height where snow remains perpetu- 
ally throughout the year, has offered unexpected difficulties in its de- 
termination for the Himdlaya. When Webb and Moorcroft first 
pointed out the general heights reached by the snow-line, when they 
first discovered the remarkable fact, that, in spite of the influence 
arising from exposition, the snow-line of the Himalaya descends lower 
on its southern (Indian) than on its northern (Tibetan) slopes, the 
statements of these travellers, now proved to be correct in all material 
points, were discredited by men of science both in Kurope and in 
India. Humboldt, however, was among the first who endeavoured 
to remove the distrust with which these discoveries were received ; 
he also gave an explanation* of the causes which were possibly suffi- 
cient to originate so remarkable a phenomenon as this of the unlooked- 
for differences existing between the snow-lines of the Tibetan and 
Indian slopes. He considers it “the results conjointly of the radiation 
of heat from the neighbouring elevated plains, the serenity of the sky, 
and the infrequent formation of snow in very cold and dry air.” Of 
all these causes, however, the last is the most important. The direct 
insolation, being less interrupted on the Tibetan side, has also its 
share of influence ; but the effect is comparatively small. As the best 
corroboration of the quantity of snow-fall being the principal cause of 
the depression on the southern (Indian) slope of the Himialaya, may 
* “ Asie Centrale,” pp. 284, 327; “ Kosmos;” Vol. I. p, 358, 
