The Greenville times. [volume] (Greenville, Miss.) 1868-1917, 1883-03-17

surface in contact with water flow
ing through the pipes would be MS
their eircumferences, that is. as
one to -four; but the quantity of
water held by each pipe is as the
square of IFS diameter, or as one
to sixteen. 1t follows, then, that
there will be really one fourth as
much friction in proportion to the
volume in the large pipe as in the
smaller one, because it haSsixteen
times the capacity and but four
fold friction. If we give to these
two piper the same inclination and
let each be kept half full of water
they will fairly represent the beds
OF two rivers, aud it will at once
be found that the current in the
smaller one viii be more sluggish
than that in the larger one, be-
cause the ratio OF friction is great
er in the small pipe. To make the
current in each the same you must
make the slope of the small one
sleeper. This steepening of the
slope is precisely what all silt.
bearing streams have the power
to do, because certain velocities
of current are required by them
to carry the silt on to the sea, and
if the stream fails from any cause
to have that velocity, part of the
silt is left in the bed and ii is rails
cd higher and higher until the ne
ccssary velocity is attained, and
then the steepening process stops.
The small pipe in this illustration
will fairly represent the South
Pass and the larger one the South
west Pass. South Pass falls 3 in.
ches per mile, and Southwest Pass
but 9 inches. South Pass disehar.
ges but one quarter as much water
as Southwest Pass, and it has 80
per cent. greater fall to overcome
the greater frictional resistance in
it. Now, it is q well-known fact
that as channel in a silt-bearing
river is robbed of its volume (as
by the Atchafalaya outlet the flow
is more sluggish below, and tho
river proceeds at once to diminish
the size of its bed below the out.
let. Each flood exten3s this dimi.
mutton of its size down towards
the sea. The ratio of friction in.
creases as the diminution extends,
and causes the water to flow moro
slowly in 1t. This sets at work the
steepening of the slope process.
The navigation suffers by the re-
duced channel, and the height of
the floods is increased.
This process is now going on be-
low the mouth of Red river, to the
injury of the river navigation, en-.
dangering at the same time the
ietty channel and involving addi'
tional heights for the levecs.
am safe in saying that those levces
require to I've at least six or elgst
feet higher than they are at this
present day. Diminishing the vol
ume of the main river will increase
the amount of shoaling and lessen
the depth of water over the bars
now existing below the mouth OF
the river. But this is not all. The
slope of the river cannot be steep
ened below Red river, except by
raising the Red river end of the
slope, as the other end is fixed by
the Gulf of Mexico. If it be raised
at Red river it will react to the
injury of the river all through the
alluvial basin above Red river. II
you raise the food line Tor slope
say five feet at Red river, you will
have just that much less slope il
the river above. | think there IL
no problem before the Mississippi
River Commission, or before the
country, or before Congress, con
nected with the Mississippi river
that is more important than tho
closure of Bayou Atchafalaya, fol
its discharge is rapidly increasing
and will continue to increase, ant
if it be not promptly checked the
whole Mississippi river will 60 ou'
through it. | speak with all the
earnestness | can command OF
this matter.
My views upon the levee ques
ton are easily stated, and l think
they can be readily understood
l do not pretend to say that tho
Improvement of the river for nav
| igation alone and independently
of any protection of the banks
against overflow cannot be accom-
plished ultimately without thu
maintenance of the levees. | vii
say even more, namely, that i
there were no levees to-day in ex
istence below Cairo, | would no
recommend the building of then
I .. - ,1.rt &c +l,o c.-ofon, of i,nnrova