Pittsburg dispatch. [volume] (Pittsburg [Pa.]) 1880-1923, 1890-12-20

dened bv mortgage, and for him made DESC
late by the mocking waters; greater values
in the homes Of those who now have them,
thousands of new homes to be made on the
lands wrested from the waters-such are the
mixed motives urging us forward. CupiditY
and humanity join hands and strive for a
common object To put an end to overfows
in the Mississippi Valley, to drain the land,
and to create in the Mississippi and its trib-
utaries a system of navigable waterways free
10 all people is the work Of an enlightened
selishness, so far-seeing as to become a
philanthropie craftsmanship. Begin the
work now. Use every proved eXpedient.
Test every suggestion that promises well.
prove all things; hold fast to that which is
good"
The energies of the Mississippi river are
greater than all the energies that man can
bring to oppose it. Instead of opposing he
must guide; he must train the river to do
his bidding" James B. Eads formulated
this great principle and applied it .prac-
ticallv on grand scale. He developed and
applied the jetty principle, creating in it an
engine of tremendous power, which must be
an essential element in any plan of perma-
nent river improvement. Jetties heretofore
built in the Mississippi river have been per-
manent works, costly in the first instance, if
misapplied total loss of investment and
liable at any time to be ren dered so by the
shifting of the river. The jetty idea in per-
manent form is well worked out.
A Movable Jetty System,
A stride forward must be made. The
jetty must be absolutely under the control
of the engineer to enable him, by shifting it's
location and varying its direction, to direct
the river and its scour with precision and
efficiency no: attainable with jetties perma-
nently located, and at the same time to ad-
Just and adapt it to the constantly varying
conditions of the river.
To this end the movable caisson jetty is
proposed, to be made of steel, of a length
proportioned to its duty, say from 500 to
LOGO feet long, deep enough to control the
river at the highest stage of water, say 40
feet deep, and wide enough TO insure stabil-
ity, to be of honeycombe1 structure, divided
into air tight cells, closed at the top and
open at the bottom. The honey
combed structure Will give strength
and rigidity and light draft so as to
make the caisson-jetty applicable at low
water stages. The upper end of each cell OF
the honeycombed structure is provided with
q hanged man-hole, covering plate, and a
valve for admitting compressed air. Sh ould
the caissOn- jetty be damaged, one of the
covering plates can be removed and an air
lock bolted on. Air being then compressed
into the injured cell, wOrkmeu can enter and
make repairs. The caissonjetty is foated
by COMPRISING air into its cells, displacing
enough water for that purpose; and when in
use the draft of the caisSon-jetty can be thus
varied, or one end or side made to draw
deeper than the other, by pumping air into
or letting il escape from a number of cells,
SO making the bottom of the caisson-jetty
coincide with an inclined river bottom.
The Jetties Well Equipped.
For the smaller tributaries smaller Gals
son-jetties would be provided, OF suitable
proportions and carrying no machinery, as
in the said tributaries 1t viii be practicable
and far more advantageous to place the
necessary machinery on the bank or upon
tender boats. For the Mississippi river,
however, and for some reaches in the Mis-
souri, and other large tributaries, the caisson-
] city should carry all machinery necessary
10 operate 1t, except its motive power.
Each caisson-jetty would therefore have
an air lock, so that internal repairs could be
made, smith aud tool shop, engine house,
with boilers and engine, powerful pumps,
air eompressors, winding engines and full
outfit of steel cables and anchors.
To scour out the river channel two caisson
ietties would be connected by cables and
held in the desired position in the stream
by means of cables secured to anchors, or to
objects on the banks. By varying the
amount of compressed air in the cells the
draft of the caisson-jeities could be ad-
Justed to the depth OF the river and the in
clination of its bottom; while the pumping
engines would enable the operators to scour
away any accumulation of sediment within
the cells, and so to prevent the caisson- -jetties
from becoming shared BY the building of
bars within or about them.
The channel between the caisson-ietties
would be contracted at their downstream
ends, and the angles of the jetties with one
another and with the current would be
varied at pleasure by taking up or paying
out the steel cables, by means of the wind
ing engines. Thus the stream would be
converged and directed to scour out its bed
in any desired direction and with the
necessary intensity; while, by giving the
ends of the caisson-ietties slight swing,
first toward one bank, then toward the other,
The channel would be excavated to a width
sufficient to enable the caisson-ietties to be
paid down stream as fast as the securing
progressed. Thus the work of channel i'm
provement would commence at the upper
end of a shoaled or obstructed section and
would proceed through into deep water in
the next bend.
The work of channel improvement would
be prosecuted uninterruptedly, the caisson
settles being worked up and down the river,