, in all
latitudes. Some it washes down from the Mountains of the Moon in
Africa, or out of the gold-fields of Australia, or from the mines of
Potosi; others from the battle-fields of Europe, or from the marble
quarries of ancient Greece and Rome. The materials thus collected, and
carried over falls and down rapids, are transported to the sea."

Here, as these substances cannot be evaporated, they would accumulate to
such a degree as to render the ocean uninhabitable by living creatures,
had not God provided against this by the most beautiful compensation.
He has filled the ocean with innumerable animals and marine plants,
whose special duty it is to seize and make use of the substances thus
swept from the land, and reconvert them into solids. We cannot form an
adequate conception of the extent of the great work carried on
continually in this way; but we see part of it in the chalk cliffs, the
marl beds of the sea shore, and the coral islands of the South Seas,--of
which last more particular notice shall be taken in a succeeding
chapter.

The operations of the ocean are manifold. Besides forming a great
reservoir, into which what may be termed the impurities of the land are
conveyed, it is, as has been shown, the great laboratory of Nature,
where these are reconverted, and the general balance restored. But we
cannot speak of these things without making passing reference to the
operations of water, as that wonder-working agent of which the ocean
constitutes but a part.

Nothing in this world is ever lost or annihilated. As the ocean
receives all the water that flows from the land, so it returns that
water, fresh and pure, in the shape of vapour, to the skies; where, in
the form of clouds, it is conveyed to those parts of the earth where its
presence is most needed, and precipitated in the form of rain and dew,
fertilising the soil, replenishing rivers and lakes, penetrating the
earth's deep caverns; whence it bubbles up in the shape of springs, and,
after having gladdened the heart of man by driving his mills and causing
his food to grow, it finds its way again into the sea: and thus the good
work goes on with ceaseless regularity.

Water beats upon the rocks of the sea-shore until it pounds them into
sand, or rolls them into pebbles and boulders. It also sweeps the rich
soil from the mountains into the valleys. In the form of snow it
clothes the surface of the temperate and frigid zones with a warm
mantle,