Pittsburg dispatch. [volume] (Pittsburg [Pa.]) 1880-1923, 1890-12-18
STILL ANOTHER PLAN
For the Improvement of the Missis-
sippi and Its Branches.
THE PROPOSED MOVABLE DAMS
Declared Not to be as Practicable as the
Permanent Affairs.
MUD OF THE MISSOURI RESPONSIBLE

Lhh D1SEA1Ch luVltcs Va INV
articles now being published on the subject
of river improvement, but intimates to the
critics the advisability of waiting until the
author has completed his task, before COM
ing to the attack. This course may be the
best il only the general conclusions of the
writer of the series OF articles in question
are expected to come into review, but there
is no harm done, 1 think, in taking notice
of some of the writer's premises already
advanced.
Thus, for instance, in his third paper he
says: ''It is obvious that a system OF per-
manent dams could be only a temporary ex-
pedlent, however great their first cost might
be, since the quantity of detritus washed
into the river would be beyond the power of
man to dredge out, and they would speedily
fill and become shallow lagoons, prolific
sources of disease and useless either for
storing flood waters or for navigation"
CALL FOR EVIDENCE.
The writer would confer benefit on the
plodding members of the engineering pro-
fession by proving that permanent dams in
our navigable rivers do fill uP, and become
prolific sources of disease. Such is not the
case with the oldest dams we have right in
the old muddy silt-bearing Monongahela
river, nor with the dams on any other large
streams so far improved in the West. On
the Monongahela the great freshets are in
creased in height only few inches by the
existence of the dams, and accordingly their
food currents being inappreciably reduced
in velocity, no increase in the deposits ex-
cepting Immediately at the dam is observed.
Therefore, as they do not become shallow
lagoons, we may dismiss the statement con-
cerniug this healthfulness-if happily it
could be proved that shallow lagoons per Sc
are breeders of disease. We must remember,
also, that the same actual quantity Of water
| will continue to flow whether the dams be-
come filled up or not
On the score of expense, adjustable dams
of any considerable height will greatly ex-
ceed in cost those Of permanent form; the
difference being as three to one, comparing
at least French adjustable dams with our
common type of crib structure. No matter
what the mechanism may be the great cost
of an adjustable dam will likely be in the
preparation of its foundation-which must
be absolutely impervious to the effects of un-
dermining, no Strengthening deposits being
permitted above them, as in the case of per-
msnent dams.
These are perhaps small matters in the
estimation of the writer-a mere trifing
with details which have OF best only an in
cidental bearing on his main proposition,
viz: The draining of the Mississippi Valley
and making it healthful, while at the same
time taking care of floods and improving
navigation.
LACK OF FUNDS.
Thanks to CAPTAIN Eads, the attention of
the people of this country has been SO directed
to the problem of Mississippi river improve
ment that the characteristics of the great
river are understood, so that there is a sub
stantial agreement as to what is required in
the premises-the chief difficulty in the way
Is the lack of appropriations to do the work
as effectually as the engineers would desire.
The great problem confronting Eads was
the means to be pursued in preventing de-
posits of mud in the river (or shoals) and
removing them when they appeared. In
his "Jetty System Explained" one of his
early pamphlets, he remarks: Gas rapidly
as the engineer strives to deepen the Missis-
sippi without proportionally contracting it,
and thus enlarges 1t beyond the capacity
which these natural forces give it,
Just so rapidly will the current
be Stacked by the enlargement and the de-
posit dropped there and thus lessen it again.
| And as fast as he may contract it just as
| fast will the current be increased and the
consequent scour enlarge it again by deep
ening it."
Nothing is simpler and truer in state
ment than these words of Eads, and it is
curious that, while the facts were before
known, no one before him seized upon them
| as fundamental maxims upon which to de-
| velop q practical theory OF river improve
ment The Mississippi River Commission
| is now at work with its leeves- mattresses,
etc., working at least in accordance with the
principles first recognized by Eads, though,
| perhaps, not with the vim he would impart
| to the operations.
ONE OF THE PROPOSITIONS.
But now arises one who proposes to 20
vastly farther than the commission or Eads
would have dared recommend. He pro-
poses to sink the surface of the Mississippi
by lowering its bed so that the lagoons or
bayous can be drained out Just how much
| deeper he proposes to make its bed has not
yet been stated, but this deepening is one of
his propositions already divulged. Ofcourse
his readers will expect to see the figures in
his final estimate. The writer knows, as a
matter Of course, that if the bed of the Mis-
sissippi is materially lowered he must keep
on lowering the beds of its navigable tribu-
| tdIles, Slse d j JuupluS oA pAoSC, VI seElcS
| OF locks to overcome the inevitable fall will
be required, and he does provide for lower
ing the bed of the Ohio.
1t was the opinion OF Lyell and other
geologists at one time, that the entire valley
proper of the Mississippi river below Cairo
for hundreds of feet in depth was all alluvial
material brought down by the river itself, or
in other words that the river flowed in a
trench of its own making. 1t is doubtless
the correct idea SO far as the top dressing of
the region is concerned. Eorings for the
Fort st. Phillip Canal project and artesian
wells elsewhere in the lower delta, however,
seem to indicate that not all the hundreds OF
feet of sedimentary material are of fresh
water origin, and the opinion is now held
that certain clay veins beneath are OF
marine origin. Some of these clay veins
are tough and not easily eroded. though the
bottom OF the Mississippi is now below the
level of some of them.
LOWERING THE BED.
The writer proposes, as understand him,
to lower the river bed-and this, according
to Eads, could only be done by confning the
one of those good, hard, tough clay veins,
Cairo. In conjunction with this work ot
deepening he proposes to straighten the
river by cutting through a number Of its
bends. trust he will think about the con-
sequence of shortening the river, viz, in
crease of its rate of descent and consequent
increase of velocity.
Suppose the river bed is deepened, say 80
feet, and one would think this not to be too
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