336 Ascent of the Jungfrau in 1841. 
eastern, western, and northern sides were clothed with snow, 
and we even remarked numerous furrows of avalanches in it. 
The fact of the highest summit being of snow and not ice, may 
be explained by its narrowness, which presents less scope for 
the action of the solar rays. 
The theory of the canon Rendu seems at first sight more 
conformable to the nature of the phenomenon. This natural- 
ist, in order to account for the ice accumulated on the summit 
of Mont Blanc, supposes that it is the product of the conden- 
sation of the vapours which continually collect round the 
higher peaks of the Alps, and annually deposit upon them a 
layer of ice of greater or less thickness. But if this were the 
case, this ice would be spread equally over all the faces of 
peaks, which is by no means the fact; we cannot, moreover, 
understand, according to this hypothesis, why the extreme 
summit should be a worse condenser than the rest of the mass. 
Lastly, as I have already shewn in a former article,* the ice 
formed in this manner should have an entirely different tex-. 
ture; it should neither contain air-bubbles, nor be rough on 
the surface, like the ice of glaciers, but should rather have the 
appearance of glazed frost (verglass). 
The bands of ice interposed between the beds of snow, 
examples of which were found in the snow-fields of the gla- 
ciers of Viesch and Aletsch, occur, according to observations 
we have made of late years, nearly every where in the pla- 
teaux of snow. Their formation is analogous to that of the 
ices which cover high summits, and is likewise to be ascribed 
to infiltrated water, since it is the only agent capable of trans- 
forming snow into ice. But if we consider that the quantity 
of water which can result from melting at such a height (fields 
of snow seldom descend below 10,000 feet) must be very in- 
considerable, on account of the great evaporation and the tem- 
perature, which does not often rise above 0° (82° F.), we must 
come to the conclusion, as has been demonstrated by M. Agas- 
siz, that these bands represent the value of the melting influ- 
ence of the solar rays, and perhaps also of the rain, on the 
surface of the fields of snow, during a given time. 
* See Bibliothéque Uniyerselle de Généye, tom, xxxii. p. 159 (March 1841. 
