THE FORMATION OF GLACIERS. 
225 
ciers, of course, determines to a great degree the 
height at which they terminate, simply because a 
small mass of ice will melt more rapidly, and at 
a lower temperature, than a larger one. Thus, 
the small glaciers, such as those of the Rothhorn 
or of Trift, above the Grimsel, terminate at a 
considerable height above the plain, while the 
Mer de Glace, fed from the great snow-caldrons 
of Mont Blanc, forces its way down to the bottom 
of the valley of Chamouni, and the glacier of 
Grindelwald, constantly renewed from the deep 
reservoirs where the Jungfrau hoards her vast 
supplies of snow, descends to about four thou- 
sand feet above the sea-level. But the glacier 
of the Aar, though also very large, comes to a 
pause at about six thousand feet above the level 
of the sea; for the south wind from the other 
side of the Alps, the warm sirocco of Italy, blows 
across it, and it consequently melts at a higher 
level than either the Mer de Glace or the Grin- 
delwald. It is a curious fact, that in the valley 
of Hassli the temperature frequently rises instead 
of falling as you ascend; at the Grimsel, the 
temperature is at times higher than at Meyringen 
below, where the warmer winds are not felt so 
directly. The glacier of Alotscli, on the south- 
ern slope of the Jungfrau, and into which many 
other glaciers enter, terminates also at a con- 
siderable height, because it turns into the valley 
