250 W. Hopkins on Changes of Climate. 
while in Iceland the two lines must nearly coincide. 
Lam not aware of other similar observations on the tempera- 
ture of the snow-line, or on the relative heights of that line and 
of the line of 32°. The height of the snow-line, however, has 
been ascertained in several other places, and the height of the 
line of 32° F. may be calculated, and their relative positions 
north-eastern Asia it is probably much greater than 3500 feet, 
ide stag 
termined. ‘Thus for the Pyrenees (lat. =42° 30’) we have by 
observation,— 
Height of snow-line........ = 9300 feet. 
The mean annual temperature at the level of the sea may be ta- 
ken at 56°, and therefore the decrease up to the line of 32° will 
be 24°; and, allowing 320 feet ascent for a decrease of 1°F., 
we shall have,— iii 
 ._. Height of the line of 32°.... =7680 feet... 
Consequently the height of the snow-line will exceed that of the 
line of freezing temperature by 1620 feet. et. 
_A sumilar caleulation for the Caucasus (lat. 42° 30’), where the 
height of the snow-line is rather more than 10,000 feet, gives the 
height of the line of 32° less than 8000 feet, and therefore lower 
than the former by about 2500 feet. And again, for the Hima- 
laya we have similar results. On the south side of this range, 10 
latitude 32° N., we may take the mean annual temperature, inde 
pendently of elevation, at 67° F., or 35° above the freezing tem- 
perature, and, allowing 400 feet for a decrease of 1° F’. in ascend- 
ing the southern slope of the mountains ($ 20, p. 48), the 
height of the line of freezing temperature will be 14,000 feet. 
The height. of the snow-line, as given by Captain Strachey, 1§ 
there 16,000 feet, or 2000 feet higher than the former line. On 
the north side of the range, allowing 2° F. in the mean annual 
temperature, independent of elevation, for the difference of latt- 
tude as compared with the south side, and 480 feet of ascent for 
each degree of temperature (¢ 20), we have 15,940 feet for the 
height of the line of 32°. Also we have, on the same authority 
as the above, the height of the snow-line 18,500 feet, or upwards 
of 2600 feet above the former line. : 
These calculated results as to the difference of heights of the 
snow-line and that of the temperature of 32° may not of them- 
selves be entitled to much confidence, compared with thant 
duced from observation; but they show that the data on W of 
the ca ‘lations are founded are in accordance with the result gi 4 
observation in other cases, __ ) cht of the 
It appears from the preceding facts, that the height of the 
snow-line, with reference to the line of 32° F., increases, Ube” 
anes. conditions, as we proceed northward from the ee 
or | on Y 
this phenomenon we may assign two principal causes, W2"" 
