The Democratic advocate. [volume] (Westminster, Md.) 1865-1972, 1900-04-28
The Force of Waves.
From Parsons Magazine.

NNoAa AcotsohS NaSa1iHe.
Many visitors to the coast are sorely
puzzled when boatman either refuses to
put off from the shore, or at most 90 far
from land, on a day when there is. no sign
of an approaching storm and the water is
only moved by a long and gentle rolling
swell.
Argument is of no avail, and if the old
salt is pushed for reason he will only
reply with some cryptogramic remark about
''the ground sea, the questioner then
retiring more bewildered than before
1t is hard to understand how such a
gentle swell can presage danger, but to
experienced eyes it gives a warning that
must be needed All along the west and
parts OF the south coasts of England and
Ireland, as well as the west coast of Scot
land, uncounted tales are told of ships
which on perfectly calm day have been
within few hours first caught by gen.
tie roll OF the water and finally thrown ON
a roekbound shore by the dreaded ground
sea. -
To understand this curious marine phe-
nomenon it must be borne in mind that
out on the Atlantic waves are often
formed to a height of 40 feet. Driven
before heavy gale, these advance at a
rate OF from 80 to 40 miles an hour.
Travelling at such rate, they soon get
out of the wind swept area. But even
though, for them, the storm is past they
still roll on in fury, their undulations often
being felt 500 miles from the point of
their creation.
In the region of the storm these waves
are fierce, breaking pillows, but as they
get farther away they settle down into
long, rolling ridges, which travel onward
in long, unbroken lines, perfectly parallel
with each other.
Out on the open sea these ridges often
stretch out for distance of over so miles.
and they travel in threes, each successive
wave being larger than its predecessor.
The sight is an imposing one.
The farther they progress the smaller
they become in height, but this is com
pensated for by the fact that their motion is
communicated to the mass of water below,
until the roll can be detected fully so feet
under the surface. This gives them the
name of ground sea. "
In this peculiarity their danger lies, for
when becalmed ship is caught in them,
her draft, the resisting power that enables
her to ride out storm, becomes the full
crum which the liquid mass uses to hurl
her onward to destruction.
On calm day any sailing craft caught
in the ''ground sea- near rocky shore is
as good as lost, unless wind can spring
up and enable her to beat out to sea.
Many ship has met this fate. The rea-
son many more do not get lost is due to
the gentle swell that so deceives land
man and warns sailor.
AS the ''ground sea- advances it pushes
a certain amount of water before it. This
also forms into ridges, like its pursuer, but
of less height and approximately no depth
The ''false sea, as it is called, is lit
tie more than rolling swell, but it gives
a warning of from 20 minutes to two
hours duration, enabling ship to either
run into port, get out to sea or securely
anchor; while at the seaside resorts the
boatmen run close in shore to the surprise
of the ''trippers" I"
When it is remembered that wave 20
feet high, which is often attained by the
Hground sea, strikes with force of one
ton to the square inch, the necessity for
caution win be recognized.
All waves that come in parellel ridges,
however, are not dangerous, as there is
"wind billow'' that is closely allied to the
"ground sea- in appearance.
"Wind pillows are due to a heavy
wind blowing but a few miles off the land,
but as they have had but comparatively
short distance to travel they have no depth
Consequently even a rowing boat is per-
fectly safe on them if properly handled.
These waves usually appear when there
is comparative calm near the shore, their
great point of difference from the "ground
sea" in appearance being that their un-
broken lines are nearer and are all equi-
distant, not travelling in threes.
Generally the ''wind billow'' does not
break into foam, but occasionally this hap
pens when they are coming in against the
tide. Then it is hard to detect them from
ordinary waves, the product of local
windstorm. These always break into foam
at their crest, the sswhite horses of the
marine poet.
Remembering these peculiarities of the
various waves will save tourists consider
able disappointment when wiser heads bid
them keep TO the land, for, to them, NO
apparent reason, while it may keep them
from rushing into unknown dangers One
other fact is also worthy of mention, as it
may prove Of advantage should boat
drift out to sea with an inexperienced crew
and no compass aboard
Then, if ii ''ground sea is s'running,"
set your mind at ease, for you can steer
by it, as, on the English and Irish coasts
at least, it always comes from the north
west.