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influence of gravity and other causes of resistance.
The pace of a deep-water wave partly
depends upon its size; a six foot wave may
run twelve miles an hour, a fifteen foot wave
fifteen miles an hour. Over the same spot
successive waves may travel at unequal
rates.

The rub of the wind over deep water does
not set the whole mass into motion. Waves
are the movements of the surface only. The
force of a tropical typhoon may indeed stir
up deep water to its recesses, but upon our
coast there are no typhoons. In gales on our
eastern coast the sea-bottom is sometimes
ground up from a depth of fifteen fathoms;
so far down, therefore, the agitation may, at
times, extend. Waves of six or eight feet
have been often seen to change water with a
depth of seven or eight fathoms. The Venus
cassina, a large shell not known to live at a
less depth than seven fathoms, often is
thrown up during heavy gales on the coasts
of Scotland, Ireland, and the Isle of Man.
At Holy Island, the Pegasus steamer, which
sank in eleven fathoms, a little to the northward
of the Goldstone, lay unhurt until there
came a fierce north-easter, when she broke
up at high-water. Examination of the Chesil
Bank at Portland Breakwater proved the
influence of waves at a depth of eight
fathoms, and the sea has been found moving
shingle towards the main at a yet greater
depth. But we are taught by the Astronomer
Royal that below the surface of a troubled
sea reduction of disturbance goes on more
rapidly than any one might at first think;
in fact, in geometrical proportion, and the
divers employed in removing the wreck of
the Royal George at Spithead, found that
they could work below as quietly and
effectively under the heaviest sea as under calm,
and that they were often most successful in
strong gales of wind. Whatever may be the
action of that part of the wave below the
level of the water, it does not operate by
beating on an obstacle, for Mr. Coode, after
ten years' experience, states that upon Portland
Breakwater even a powerful breaker
does not inflict any blow below a depth of
twelve or fifteen feet from the level of the
water.

The crests of deep-sea waves, first sharpened
by the wind, then broken and blown
over as foam, are not for their resemblance
to the foam of breakers, to be dreaded as the
breakers are. Such foam is but dead water
that has less speed than the wave from which
the gale is dashing it. Spray of this kind,
seconded by the plunging of a vessel, may
make havoc with feeble bulwarks, or sweep
light boats from a deck, but it is powerless
against the sharp bow of a vessel by which
it is breasted, and even the Dutch fishing
vessels ride at anchor unharmed in the midst
of it. A very slight obstacle will reduce
what size and force it has. Admiral Bullock
has seen even fishermen's nets cut off the
crest of a deep-sea wave, and produce
comparatively smooth water under their lee.
Boats driven off shore by gales of wind have
been saved with their crews by riding under
the lee of their spars formed into a raft, over
which the surface-drift has spent itself. At
the Cape of Good Hope a sea-weed baulks
these ocean breakers, and the effect of oil
upon the troubled waters has become a
proverb. Fishermen have towed masses of
greasy garbage behind their boats to destroy
a following sea; and before Franklin
recommended pouring oil upon the waves, the
Steward of Kilda, in one of the Western Isles
of Scotland, used, in a storm, to tie a bundle
of puddings made of the fat of the sea-fowl to
the end of his cable and let it fall into the
sea behind the rudder. This hindered the
waves from breaking. When, two years
ago, the screw-steamer William Beckett of
Goole foundered off the Scaw, the crew
escaped through a heavy sea solely by use of
oil. Dutch fishermen are sometimes to be
seen entering the harbour of Scarborough, in
heavy weather, cutting off the crests of the
following waves by diffusion of oil over the
surface of the water, thus giving the wind a
greased surface to rub over, as roughly as it
would, and establishing a broad smooth wake
behind the vessel. And when the wind's
work has been thus destroyed, it needs time
and space to work in before anything like
the old force of the suppressed wave can be
re-established. By the force of tides or
friction deep-water waves may also be
intercepted, retarded, reversed, redirected, and
destroyed. Mr. T. Stevenson says, that
"From observations specially made at
Sumburgh Head Lighthouse, in Shetland, during
a westerly storm, so long as Sumburgh
Roost (one of the most formidable tide-ways
in those seas) was cresting and breaking
heavily, one could easily have landed in a
small boat at a creek, or bay, called the West
Voe; but no sooner did the Roost disappear
towards high water, than there came in
towering billows that totally submerged
cliffs of very considerable height." Again,
deep-water waves heaping themselves up
against a steep and rocky line of coast, fall
back and establish a reversed system of
undulation that reduces the height of the waves
next coming in. By such recoil Mr. Calver
thinks, from his own observations, that one-
third of the original height of the advancing
wave is lost.

With these deep-sea waves we have now to
contrast the breakers formed in shoal water.
As the depth lessens the rate of movement
in the lower part of the wave is retarded by
increase of friction at the bottom, the greatest
speed is at the top, and the front of the wave
therefore becomes erect, leans forward till its
top overhangs its base, and falls with a tremendous
force upon the shore, or upon any solid
object that may lie beneath its stroke. Such
a wave, roughly speaking, breaks when its

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