The ground above and near the cave is covered with beech and chestnut
trees, and thus is protected from the rays of the sun. The leaves of
these trees give forth abundant moisture, which has been pumped up
from their roots; and as this moisture passes from the liquid to the
gaseous state, it absorbs a large quantity of caloric. Thus,
throughout the summer, the atmosphere is incessantly refrigerated by
the evaporation produced by the trees round the cave; whereas in
winter no such process goes on, and the cave assumes a moderate
temperature, such as is usually found in ordinary caves. Unfortunately
for M. Cadet's theory, the facts are not in accordance with his
imaginary data, nor yet with his conclusions. He adds, on the
authority of one of his friends, that the intendant of the province,
M. de Vanolles, wishing to preserve a larger amount of ice in the
cave, built up the entrance with a wall 20 feet high, in which a small
door was made, and the keys were left in the hands of the authorities
of the neighbouring village, with orders that no ice should be
removed.
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