The telegraph manual: a complete history and description of the semaphoric, electric and magnetic telegraphs of Europe, Asia, Africa, and America, ancient and modern.

654 OCEAN TELEGRAPHY.
The rays of the sun cannot penetrate into the depths of the
ocean, and radiation cannot take place thence; consequently,
the change of the temperature in the depths of the sea, from
summer to winter, and winter to summer, must be almost, if
not entirely, inappreciable. This is a generally admitted fact.
The winds take up water from the surface, and not from the
depths, and in so doing, they disturb the equilibrium of the
water at the top, not the equilibrium of the water at the bottom; by evaporation, the water becomes salter and heavier
than it was before, the vapor thus taken up is condensed into
rain and precipitated on other parts of the sea-thus both
raisinig the sea level, and making the water lighter and less
salt than it was before. Thus we have the genesis of horizontal circulation, or an interchange of water called currents. If
by the process of evaporation, the surface water becomes so
salt as to be heavier than the water at the bottom, the water
at the bottom and water at the top will change places. This
may give rise to a vertical circulation, but one so feeble that
it cannot be felt, by even the tiny little shells which strew the
bed of the ocean, and which lie there as lightly as gossamers
under the dew of the morning; practically, therefore, the
water at the bottom is still.
It is also generally admitted that the waves, even in their
most angry moods, are incapable of reaching far down in the
sea, or of disturbing the quiet and repose which reign in its
depths.
In short, there is reason to believe, that the bottom of the
deep sea is everywhere protected from the violence of its waves,
the abrading action of its currents, and the rage of the forces
which are ever at play on its surface, by a cushion of still
water.
The grounds for this belief are afforded by these circumstances: everywhere, whencesoever specimens of bottom have
been obtained by the deep sea plummet, they have been found
to consist of the untriturated remains of the microscopic organisms of the sea. Some of these have the flesh of the little
creatures still in them. Now these feculences of the sea, as
the remains of its microscopic inhabitants may be called, are
relatively as light in the water, as motes in the air; and, if
the bottom of the sea were scoured by its currents, those sea
motes would be swept away into drifts like snow or into dunes
like sand, they would be scratched, their sharp corners and the
edges would be broken off and rounded. Moreover, were they
drifted about, then sand and other scourings of the ocean would
be found mixed with them. But not so, the specimens brought