Rock Island Argus. (Rock Island, Ill.) 1893-1920, 1899-11-09
THEFORCEOFWAVES.
GENTLE ROLLS OF WATER THAT
LID A FEERF.L POWER.

Ground Seas on the English Const
which Wreck Vessels on Calm
Days-These SweIIs Strike With n
Force of a Ton tn the Square Inch.
Many visitors to the coast are sorely
DuzzIed when 4 boatman either refuses
10 put off from the shore, or ut most
go far from land. on n day when there
is no sign of an approaching storm
and the water is only moved by long
and gentle rolling swell
Argument is of no avail, and if the
old salt is pushed for 4 reason he will
only reply with some cryptogramic re
mark about the ground sea-" the
questioner then retiring more Devil
dered than before.
1t is hard to understand how such
gentle swell can presage danger, but
to experienced eyes it gives 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 Scotland, uncOunted
tales are told of ships which on per
fcctly calm day have been within q
few hours first caught 10y gentle roll
OF the water and finally thrown on q
rOcIsbound shore by the dreaded
ground sea"
To understand this curious marine
phenomenon ii must he borne in mind
that out on the Atlantic waves are Of
ten formed to a heiGh of 20 feet. Driv-
en- before Il heavy gale, these advance
ut rate of from 80 to 10 miles an
hour. Travelling at such Il 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 undul2tions often being felt 800
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. urbroken lines,
perfectly parallel with each other.
Ont on the open sea these ridges Of
ten stretch out for distance of over
80 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 small
or they become in height. but this is
compensated for by the fact that their
motion is communicated to the mass of
water below. until the roll can be de-
tected fully % feet under The surface.
This gives them the name of ground
sea-
In this popularity their danger lies,
for when bccalmed ship is caught in
them, her draft. the resisting power
that enables her to ride out Il storm,
becomes the fuicrum which the liquid
mass uses to hurl her onward to de-
structiou.
On Il calm day any sailing craft
caught in the ground sea" near 4
rocky shore is as good as lost, unless a
wind can spring up and enable her to
beat out TO sea. Many n ship has met
this fate. The reason many more do
not get lost is due to the gentle swell
that so deceivcs Il landSman and warns
sailor.
As the ground sea" advances it
pushes n certain amount of water be-
fore it. This also forms into ridges.
like its pursuer, but of less height and
approximately no depth.
The false sea- as il is called, is lit
tie moro than rolling swell. but it
gives a warning of from 20 minutes to
TO either run into port, get out to sea
or securely anchor; while at the sea-
side resorts the boatmen run close in
shore to the surprise of the ''trippers.'
When it is remembered that a wave
20 feet high. which is often attained by
the ground sea" strikes with Il force
of one ton to the square inch. the ne
cessity for caution viii be recognized.
i
ridges. however. are not dangerous. as
there is Il wind billow'' that is closely
allied to the ground sea- in appear
ance.
Wind pillows" are due to a heavy
wind blowing but Il few miles off the
land, but as they have had but Il COM
paratively short distance to travel they
have no depth. Consequently o."