The Cecil Whig. [volume] (Elkton, Md.) 1841-current, 1875-09-04
THE MISSISSIPPI JETTIES.

The work was begun by capt. EadS OF
the 18th of June, and its progress already
gives such tokens of success that he believes
that the largest ships sailing out of tn.
harbor of New York will be able to entel
the mouth of the Mississippi without risk
or delay before this year ends. Yet the
South Pass, upon which the work of i'm
provement is undertaken, formerly hac
less than seven feet of water on the bar
Little more than two months have elapsed,
and much of that time has necessarily beer
spent in gathering materials, building
houses for workmen, and perfecting other
preparations. But the work has already
had the effect of deepening the channel
fully seven feet at the head of the works.
The plan adopted is remarkable for its
simplicity. The general aim, as is vel
known, is to confine the waters of the
mouth within straight parallel walls, sc
proportioned in width to the quantity o.
water escaping as to produce a certain
velocity of current, and force the stream
to scour out channel for itself of required
depth. The great difficulties of the prob
lem were only in devising means of Great
ing these artificial walls, and making them
secure and permanent upon the exceedingly
unstable foundation afforded. The Mis-
sissippi river empties itself over sediment
many feet in depth, deposited by itself, and
through walls of such sediment in like
manner thrown up on either side by it,
current. In effect, foundation and wall.
are of soft mud, into which any works o.
stone would speedily sink and disappear.
Piles alone, or crib-work, however firmly
placed, would soon be undermined and
swept away by the scour of the current
To meet these difficulties, which have
seemed to some engineers almost insupera-
BILE, Capt. Eads builds the artificial walls
of the river with broad, flat mattresses Of
willow brush, securely dashed together, and
anchored to an interior row of piles. The
preliminary work is the driving of piles,
along and inside of the line proposed fol
the artificial structure. Meanwhile great
mattresses of brush are constructed, firmly
locked together with cross bars and hickory
pins. These mattresses, 40 feet wide and
only 3 feet thick, are towed into position
adjoining the piles and fastened to them
If placed at night, by morning the deposit
of sediment from the current has so fillet
the interstices as to sink them, so that they
rest upon the bottom, and the sediment
continues to gather in upon them unit
they become more solid and enduring thar
any part of the natural bank. For the
current may at any time scour away the
natural bank with rapidity, but the resist
ance offered by the willow brush effectually
prevents any displacement of the sedimen
lodged within its interstices. When com
pleted, the wall of mattress will perfectly
protect the row of piles from the current
while the piles serve to hold the mattresse.
in position, and the whole will be covered
with firm stone paving, protecting TIT
surface from the assault of storms. Tht
outer ends of the walls, where they arr
exposed to the sea, will also be constructed
of much broader and stronger mattresses
supporting solid and durable works. 1
will be work of years to complete thu
whole structure, but the channel will rapid
ly deepen as fast as it is confined within
narrower limits by the artificial walls. Il
is calculated that these will be so far com
pleted before this year ends that the larges
ships ever seen in New York Harbor cal
enter the South Pass at any time, anC
proceed without delay to New Orleans.
OF the preliminary line of piles, 9,S6(
feet have now been driven on the east jetty
and 1850 feet on the west jetty, while
$500 feet of the mattress foundation have
already been securely laid. Each mattress
is not only fastened to others adjacent anC
to the piles, but anchored in its place by {
layer of stone. But those who understand
the rapidity with which the river will
create an enduring bar in a few hours
merely by deposit of its sediment in ant
around the top of a tree which happens tt
lodge in and check the current, and who
know with what extreme difficulty sucl
bars are removed, will realize that thu
artificial walls which Capt. Eads creates
are anchored more firmly by the river!
own deposits than it would be possible
otherwise to anchor them by any human
device. The laying of these mattress foun
dations goes on at the rate of 300 lineal
feet per day. The utmost confidence il
now felt by Capt. Eads and his associates
that the work will secure the desired depth
of water at the mouth of the Mississippi
within a few months, whereas any Other
plan would have required years. If hi:
expectations are realized, it will be mag
nificent triumph of engineering skill, il
which all who have an interest in the com
merce of the Mississippi Valley or of the
Gulf will heartily rejoice.