M.
M. Thury remarks that less current was to be expected in winter than in
summer, because the upper ends of the fissures would be probably choked
with snow, and their lower ends with ice. It is evident that the current
which passes up into the fissure in winter, is favourable to the
introduction of the colder air from without; while the opposite current
in summer keeps up a supply of cold air in the cave, and so increases
its powers of resisting the attempts of the heated external air to make
a partial entrance. Both these currents, then, favour the glacial
conditions of the cave, and to some extent counterbalance the
disadvantages of its situation: viz., its aspect, towards the
south-east; the large size of its opening to the air, and the absence of
all shelter near the mouth, such as is so often provided by trees or
rocks. The small depth of the cave, scarcely amounting to 18 feet below
the level of the entrance, is also a great disadvantage.
The people of Pralong asked, on the return of the party, what had been
found in the _grand' cave_, and the answer reduced them to silence for a
few moments.
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