Memphis daily appeal. [volume] (Memphis, Tenn.) 1847-1886, 1878-05-18

|
success. their example may be safely and adj
vantageouslv followed.
| MISSISSIPPI RIVER IMPROVE
MENT.
The advantages that have resulted from
the opening to the gulf made by the levees
have been so decided, and the commerce Of
the rivers so much extended in consequence,
that it is strongly felt that the navigation of
the river itself must be so improved as to
make the advantages of the jetties fully
available. The extension of river navigation
adds to the value of lands upon its hanks,
and it becomes doubly important, therefore,
that the splendid aIluvial lands on its lower
course should be rescued from overflow and
be put in a condition to add to the revenues
and wealth of the nation. The plan pro-
posed by Captain Eads of bringing the entire
river to an approximate width, by that means
securing regular flow of the current, and
as result regular carrying off of the sedi-
ment held in suspension by the
water, and a regular depth without
shoals or bars The excellence of the plan
| of Captain Eads ia that his system which
| has proved SO successful in the jetties, is
equally available for the purpose of render
ing the river navigable at all seasons where
unobstructed by ice, and for securing out
the shoaly places, and giving an even slope
to the bed that calamitous overfows can no
longer occur. In this way no addition will
be required to the established hight of the
levees, for the river bed will not keep rising
higher, as it did under the old levee system,
but the bottom will cut out as it has done at
the jetties, and so secure the lands adjacent
permanently and satisfactorily. This plan of
Captain Eads has also the excellent quality of
bringing the people along the whole river and
its tributaries into alliance upon the subject,
so that they will come before congress with a
weight of votes and influence that are ire
sistlble. The west and the south along the
rivers have only to fully to understand the
position of things to be united, and to be
united is undeniably to effect their purpose.
Of course there are persons who, from
prejudice or self-interest, desire
to prevent such a union. Some
parties, welded by habit To the old levee sys-
tenn, spite of its fragrant defects, would hold
up the old plan of having the lower river peo-
pie clamoring for levees, while those on the
upper stream were straining their energies
for improved navigation facilities. So divid-
ed, both would fail. Others there are who,
in spite of the demonstration afforded by the
great jetty experiments, would try Humphrey
draw off a portion of the waters of the river
at various intervals, and by decreasing the
volume expect to prevent overflow. Were
the bottom and sides of the river solid, and
the water flowing in 1t pure, the plan would
do, but as the river is constituted by nature
it would infallibly fail. The amount of sedi-
ment carried by the river depends exactly on
the speed of the current. If the reader would
be sure correctness of this assertion
and it is supreme importance In this
connection-let him put couple of tea
spoonfuls of sand in a tumbler, then fill
third of the glass with water. Shake the
glass and certain amount of sand will be-
taken up by the water. Shake harder and
more sand will be taken up. Gradually make
the motion slower, and more and more sand
will fall to the bottom. This experiment
shows that the amount of sediment held in
suspension by the river is exactly proper
toned, other things being equal, to the speed
with which the water moves. Now let US
apply this to the outlet plan. At a certain
part of the river the current is running at
certain srate, and of course carrying the
amount of sediment due to that rate. Then
occurs an outlet from which a portion of the
water that was in the river is drawn off, leAv-
ing the remainder to flow on along the usual
channel. But the quantity of water being
lessened, the impetus the whole exerted Is
partially lost, the water flows with less ra-
pidity-a dIminution of speed that in some de-
gree neutralizes the effect of the outlet as a
was the case with the experiment in
the tumbler, the decrease of speed in
the current is accompanied with fall to the
bottom of portion of the sediment held in
suspension. The result of this is shoaling
of the water, the bottom being less distant
from the surface than before. That tins is
actually the effect of outlets upon the stream
was strikingly manifested by tie crevasse
known as Jump and Cubit's gap, where about
twenty pei CCAb' VI tlS "a1ci III euc AifoA
flows out of its channel. A few miles below,
since the crevasse occurred, the depth of the
river has been reduced one-fourth, being thir-
ty feet where before 1t was forty. AS the agi-
tation of the levee and river improvement
subject proceeds, our readers will hear much
about the ''outlet" system. If we have made
the subject plain, and especially if the little
experiment we describe is tried, our readers
will be free from having dust thrown into
their eyes" in connection with it. They will
know the outlet system is based upon false
hypothesis, and they will see that Captain
Eads's plan is scientific in its foundation and
practical in its details.