Lexington weekly intelligencer. (Lexington, Mo.) 1871-1887, 1875-09-04
A Word About the Jetties.-

Captain Eads has laid the plans
for his %jetties before o commission
of engineers appointed by the pres
ident. Work was begun on June
14tb, and the improvement in the
channel is already Sc marked that it
is confidently expected that before
the close of the year the largest ships
sailing out of the harbor Of New
| York, will be able to enter the mouth
of the Mississippi without risk or
delay.
Captain Eads, dertook this
stupendous work with the under
standing that he should receive moth
ing until certain stipulated depths
of water should be secured and main
tanned.
The act of congress provides for
the payment of o certain sum when
twenty feet had been secured, aud
an additional sum when u depth OF
twenty two feet had been secured,
and &c on up to thirty feet. Twelve
months after each required depth
has been secured, q further, sum
shall be paid. if that depth during
that time shall have been maintained.
And 100000 a year is to be paid
for twenty years for maintaining the
works.
The following description Of the
method by which this interchangeable
engineer proposes 10 accomplish his
moro than herculean task is coz.
densed from the New York Tribune.
The most remarkable thing about il
is it's simplicity.
The general aim, as ia well known
is to confine tho waters of the mouth
within straight parallel walls, so pro.
portioned in width to the quantity OF
water escaping as to produce a Ger
tain velocity of current. aud force tho
stream to col 3 channel for itself OF
required depth. The great difficulties
of the problem were only in devising
means OF creating these artificial
walls, aud making them secure and
permanent upon the exceedingly un'
stable foundation Afforded. The Mis'
sissippi river empties itself over sed'
iment many feet in depth, deposited
by itself, and through walls of suci
sediment, in like II thrown UP
on either side by its current. In eff.
feet, foundation and walls are of soft
mud, into which II works of stone
would speedily sink and disappear
Piles alone, OF crib-work, however
firmly placed, would Don be unde"
mined and swept away by the scoul
of the current. To meet these diff
culties, which have seemed to some
engineers almost insupcrable, Capt
Eads builds the artificial walls of the
river with broad, flat mattresses o!
willow brush, securely dashed togeth.
er, aud anchored to LII interior %
of piles. The preliminary work is
the driving OF piles, along and inside
of the line proposed for the artificial
structure. Meanwhile great mattres
SEES of brush are constructed, firmly
locked together with crossbars anC
hickory pins. These mattresses, forty
feet wide and only two feet thick, ar,
towed into position, adjoining tht
piles and fastened to them. If place.
at night, by morning the deposit o
sediment from the current has so tillet
the interstices as t. sink them, SO tina
they rest upon the bottom, and thu
sediment continues to gather in upol
them until they become more sole
and enduring than any part OF the
natural bank. For the current may
at any time scour away the natura
bank with rapidity, but the resis
lance offered by The willow brush eff
fectually prevents any displacement
of the sediment lodged within its in
lerstices. When completed. the wal
of MATTRESSES will perfectly protect tin,
row of piles from the current, while
the piles serve to mold the m%at.resse.
in position, and the whole will bt
covered with a firm stone paving
protecting the surface from the as
sault of storms. The outer ends o
the walls, where they are exposed t,
the sea, will also be constructed o
much broader aud stronger mattres
ses. supporting solid and durable
works,