which preserves vegetable life from the killing frosts of
winter. In the form of ice it splits asunder the granite hills; and in
the northern regions it forms great glaciers, or masses of solidified
snow, many miles in extent, and many hundred feet thick. These glaciers
descend by slow, imperceptible degrees, to the sea; their edges break
off and fall into it, and, floating southward, sometimes in great
mountainous masses, are seen by man in the shape of icebergs.
Frequently huge rocks, that have fallen upon these glaciers from cliffs
in the arctic regions, are carried by them to other regions, and are
deposited on flat beaches, far from their native cliffs.

The saltness of the sea rendering it more dense, necessarily renders it
more buoyant, than fresh water. This is obviously a great advantage to
man in the matter of commerce. A ship does not sink so deep in the sea
as it does in a fresh-water lake; hence it can carry more cargo with
greater facility. It is easier to swim in salt than in fresh water.

The only disadvantage to commerce in the saltness of the sea is the
consequent unfitness of its water for drinking. Many and harrowing are
the accounts of instances in which sailors have been reduced to the most
terrible extremities for want of fresh water; and many a time, since
navigation began, have men been brought to feel the dread reality of
that condition which is so forcibly expressed in the poem of the
"Ancient Mariner":--

"Water, water everywhere,
And not a drop to drink."

Science, however, at length enabled us to overcome this disadvantage of
saltness. By the process of distillation, men soon managed to procure
enough water at least to save their lives. One captain of a ship, by
accident, lost all his fresh water; and, before he could put into port
to replenish, a gale of wind, which lasted three weeks, drove him far
out to sea. He had no distilling apparatus on board, and it seemed as
if all hope of the crew escaping the most horrible of deaths were
utterly taken away. In this extremity the captain's inventive genius
came to his aid. He happened to have on board an old iron pitch-pot,
with a wooden cover. Using this as a boiler, a pipe made of a pewter
plate, and a wooden cask as a receiver, he set to work, filled the pot
with sea water, put an ounce of soap therein to assist in purifying it,
and placed it on the fire. When the pot began to boil, the steam passed
through the pipe into