Ascent of the Jungfrau in 1841. 335 
covers the highest ridge of the Jungfrau has all the characters 
of the ice of ordinary glaciers; the same hardness, the same 
angular texture, the same roughness of surface, the same ca- 
pillary fissures. It differs only in being of a less bluish tint, 
which is no doubt owing to the greater number of air-bubbles 
it contains ; in this respect it more resembles the ice of gla- 
ciers in winter. Its thickness probably undergoes more or less 
considerable variations; we found it perfectly homogeneous, 
without any trace of intercalated snow as far as the hatchet 
penetrated; that is to say, nearly to the depth of a foot. It is 
only close upon the summit that it begins to lose its hardness, 
and for the last twenty feet it again becomes granular snow. 
No one, in my opinion, has hitherto explained this pheno- 
menon in a satisfactory manner, although it in every respect 
deserves careful consideration, were it only on account of the 
difficulties it presents. All now nearly agree in admitting 
that the ice of glaciers is snow transformed into ice by means 
of water, which, by congealing, acts like a cement. The more 
frequent these alternate infiltrations and congelations are, the 
greater compactness the ice acquires. Thus, when, ascending 
a glacier, we reach a point where the névé gives place to inco- 
herent snow, we conclude that this arises from there not being 
enough of water to cement it, and that appears to us natural 
enough, knowing as we do that the temperature goes on di- 
minishing as we rise upwards. But how then does it happen 
that the summits, which are highest of all, and consequently 
surrounded with a colder atmosphere, are covered with ice ? 
Without pretending to solve this problem in a definite man- 
ner, I still think that we may find a partial explanation in the 
detached situation of these high peaks, which are more ex- 
posed than the lower plains to the action of the solar rays and 
to that of winds. Suppose the wind to carry off the snow as 
fast as it falls, the sun will then have time to change all that 
remains into ice; in this case, the broad surfaces exposed to 
the south will necessarily be more affected by the action of 
the sun than the narrow surfaces and such as are turned to the 
north ; and this is, in fact, what appears to take place. We 
remarked, while ascending the Jungfrau, that while the south- 
ern slope, on which we travelled, was covered with ice, the 
