The Lee County journal. (Leesburg, Ga.) 1904-19??, 1906-03-23
1s- @~aHHG1AH 6gEFEg

Fzs-Tl NE of the most interesting
9 G phases of modern engineer.
ing is that dealing with the
I-O protection of our shores
N9l l.s from the encroachments OF
the sea. 1t is a matter OF
common knowledge that in many
places on the coastline valuable land
is yearly swallowed by the sea, and
that the limit of high water mark is
steadily creeping inland. Most people
also know that there are many other
places where the reverse of this is
happening. and the land is actually
gaining upon the sea. 1t is reserved,
however. to very few, even among en-
gineers. to know the methods which
have been and are being taken, in the
one case. to counteract these encrOach-
ments. and. in the other, to retain pos
session of the accumulated accretions.
With the exception Of a very few
places where trade and shipping have
necessitated harbor defensive works,
the sea has for ages been allowed to
work its own will on our coasts, UNI
interrupted to any extent by man, I'M
til within the last few years. Where
the sea has given up some land, and
has receded somewhat, man has been
bold enough to ''reclaiH" the gift, but
the birth Of active successful measures
towards compelling it to cease erosions
here and to give accretions there be-
longs only to the last decade of the
last century.
ExperimS nts made with the many
systems advocated at various times
by different experts have served to
prove a few general principles which
seem fairly applicable in the majority
of cases of erosion. The most obvious
remedies to be applied are those of the
sea-wal and the dyke, and these have
been multipliedin all conceivable forms
and shapes. It was early recognized
that to oppose a vertical face to the
progress of the sea was to invite disas-
ter. The water, especially during a
storm, exerts a most serious securing
action at the bottom of such wall,
and quickly bares it foundations, after
which breaches become easy.
To minimize scOur, aprons have been
constructed at their bases, consisting
of stone. brick or cement beds laid
against the toe of the wall and extend
ed at q greater or less angle Outwards
towards the sea, and so protecting
their foundations. The process of trial
and error has, however, shown that
vertical walls are unsuited for these
purposes. and that the greater slope or
batter than can be given to their face,
the more successful they are. Prob
ably the best form of face that can be
given is elliptical, as fiat as possible,
arranged so as to minimize all batter
ing action of the waves, and protected
by a substantial apron at the toe. Even
under the most favorable conditions,
however, scOur will in time result,
and constant attention is required to
see that extensive denudation at the
base does not take place.
Sea walls at their best are, however,
only a passive agency, and means have
been sought to combat more actively
the ceaseless action of the tides. Up
to the present, the greatest success has
been attained by the use of groynes.
Observation has shown that the sand
and single of the coast are constantly
changing their position and are I'M
ceasingly drifting in directions pecu-
liar to every separate place. A groyne
is merely an obstruction designed to
arrest in the best known manner the
solid matter washed up or carried in
suspension by the waves, so that the
coast may become gradually built up
instead of denuded. When groynes
were first built they were of what is
known as the high" type, in contra
distinction to the now much more fay-
Ored "low" type. High groynes, such
as those of Hastings, usually placed at
right angles to the shore line, undoubt-
eddy collect a lot of sand and single,
but it is only on one side, the other
side not only not arresting matter, but
in most cases being so subject to scour
that there often appears to be as much
distracted from the one side as is
gained 10 the other. The manifold dis
advantages of high groynes have led
to o very general trial of the low, or
case, system of grooming.
The fundamental principle of this
system is that of constructing the
groynes at a Slight elevation only
above the beach-this being claimed
to prevent scour on the lee side-and