have acted upon the ice to a certain
superficial depth, so that its surface is covered with a decomposed
crust of broken, snowy ice, so permeated with air that it has a
dead-white color, like pounded ice or glass. Those who see the glacier
in this state miss the blue tint so often described as characteristic of
its appearance in its lower portion, and as giving such a peculiar
beauty to its caverns and vaults. But let them come again after a summer
storm has swept away this loose sheet of broken, snowy ice above, and
before the same process has had time to renew it, and they will find the
compact, solid surface of the glacier of as pure a blue as if it
reflected the sky above. We may see it in the early dawn, before the new
ice of the preceding night begins to yield to the action of the sun, and
the surface of the glacier is veined and inlaid with the water poured
into its holes and fissures during the day and transformed into pure,
fresh ice during the night,--or when the noonday heat has wakened all
its streams, and rivulets sometimes as large as rivers rush along its
surface, find their way to the lower extremity of the glacier, or,
dashing down some gaping crevasse or open well, are lost beneath the
ice.

It would seem from the quantity of water that is sometimes ingulfed
within these open breaks in the ice, that the glacier must occasionally
be fissured to a very great depth. I remember once, when boring a hole
in the glacier in order to let down a self-regulating thermometer into
its interior, seeing an immense fissure suddenly rent open, in
consequence, no doubt, of the shocks given to the ice by the blows of
the instruments. The effect was like that of an earthquake; the mass
seemed to rock beneath us, and it was difficult to keep our feet. One of
these glacial rivers was flowing past the spot at the time, and it was
instantly lost in the newly formed chasm. However deep and wide the
fissure might be, such a stream of water, constantly poured into it, and
daily renewed throughout the summer, must eventually fill it and
overflow, unless it finds its way through the whole mass of the glacier
to the bottom on which it rests; it must have an outlet above or below.
The fact that considerable rivulets (too broad to leap across, and too
deep to wade through safely even with high boots) may entirely vanish in
the glacier unquestionably shows one of two things,--that the whole mass
must be soaked with water like a wet sp