Memphis daily appeal. [volume] (Memphis, Tenn.) 1847-1886, 1874-06-20

as fast. So it could easily carry Off five
or six times as much water as IL now
does. From the mouth of the Missouri
TO the Gulf on a straight line is about
675 miles, with an average descent OF
about eight inches to the mile, but the
Mississippi winds and curves so much
that IL runs 1900 miles In that distance,
and thus reduces It's average rate of de-
scent to about four inches to the mile.
Sometimes in running twenty-five
miles round a bend 1t has not ad
vanced forward q single mile. The
traveller on a steamboat descend
ing the river, and therefore of course
going south, will often discover with
surprise that for miles at 8 time be is
going north. Half the time he is NOV
ing east or west. He becomes sadly be-
wildered, but tries to have faith that the
river knows where it is going, and at
least will not run up hill.
WIDTH OF RIVER = IT GROWS MAR
ROVER.
Il is q strange peculiarly of the won
derful river that as 1t proceeds down.
ward in its course toward the gulf in
stead of growing wider, as you would
expect, IL actually becomes much mar
rover. From the mouth of the Ohio,
1850 miles above the passes, which are
only few miles above the gulf, to the
mouth of the Arkansas, $40 miles above
them, the average width in time of high
water is 4470 feet, the depth 81. From
there to the mouth of Red river, 300
miles from the passes, the width
is 1850 feet, the depth SO.
From Red river down to Bayou
LafouTehe, which is 170 miles above
them, the width is 5000 feet, the depth
ll3. From there to the passes, or for
the last 100 miles, that the river flows in
a single channel, the width is 2740 feet
and the depth l29. 1t will be observed
that as the river becomes narrow il
grows deeper as a compensation. The
reduction of its width, however, from
4470 to Z740 feet is very striking. Ithas
actually lost two thousand feetin width.
may mention that the river loses at
least oue-tenth of its mean width as the
season of low water sets in. At such
times its mean width from the mouth
Of Red river to Bayou Lafourche is
2750 feet, and from there to the passes
only 2250 feet.
RANGE OF DEPTH.
The rise and fall of the waters OF the
river, or the difference between the
highest and the lowest waters, is an
other and the greatest difficulty in con-
trolling the Mississippi. AT Cairo, and
also at Natchez, $50 miles from the
Gulf, 1t is 81 feet; al Ienphis, 40; at
mouth Of Red river, A; at Bayou La
lourche, "a; at New Orleans, nearly Is;
at Fort st. Phillip, AZ; at the passes,
where the river forks into several chan
nels, only some ten ortwelve miles from
the Gulf, it is about q feet, aud at the
Gulf Of course nothing.
VAST AMOUNT OF SEDIMENT.
The immense amount of mud and sed-
iment suspended in the waters of the
rivers, especially during the floods, is
another difficulty. Able engineers have
computed that it annually carries into
the Gulf in suspension enough precious
soil to form q solid mass one mile square
and two hundred and forty-one feet
high, Others think it carries far more.
The best authorities estimate the weight
of the sediment so carried at more than
4C6, ,000, 900 tons. But besides this i'm
mense amount, it deposits vast quanti-
ties on its banks, and all over the cOun-
try oveTflOwed in time of ii DOds. Rqsh-
ing along at such times at the rate Of six
miles an hour, and in the middle of its
current on the surface more than seven,
its madly-whirling waters are loaded
with sediment. But as soon as the wa
ters pour ever its banks they begin to
move much more slowly, aud drop a
large portion Of their solid matter at
once on or near the banks, and thence
in diminishing quantities for miles, till
they reach the swamps. In this way
it comes to be a fact that the land, as you
go back from the river, slopes downward
for miles. The banks become in time
much higher than the land farther back,
the slope in the first mile bsing from
three to twelve feet, and on an average
fully seven. Hence the river runs, as it
were, in the center of vast ridge few
miles wide and as long as the rivers
course. In time of highest waters it
rises as high as the top of this great
ridge and higher, but the mass Of its
waters remain in its bed, which is from
one hundred to one hundred and fifty
feet deep.
UNDERMINING AND FALLING IN OF ITS
BANKS.
But the undermining and constant
caving in of its banks is the great anu
enormous trouble in regard to the Mis-
sissippi. Deep down below the twenty
or thirty feet Of surface-soil deposited at
some time by the river, are vast beds OF
clay; beneath them are immense layers
Of sand, often sixty or eighty, or even
one hundrsd feet below the top of the
banks. The two, however, are often
strangely intermixed and interspersed,
the one with the other. The current OF
the river washes out the sand, and the
banks, thus lett without support, sooner
or later give way and tumble into the
waters, which speedily transport them
elsewhere in the form of sediment. or
ofteneT roll, and push and whirl them
along for a mile or two, or less, until
they aid to form sand-bars or islands, or
new banks lower down. Niagara river
works its way during the slow centuries
in a somewhat similar manner up to-
ward Lake Erie; only there it is an I'M
der stratum of soft rock or shale, instead
of sand, hundred feet beneath the bed
OF the river, that by degrees is washed
away, and leaves the hard superincum-
bent rocks to fall by their own weight.
TOWNS WASHED AWAY.
Whenever the current is DETECTED to-
ward either bank, as often occurs and
always in concave bends, the bank as
sailed, if of soft and yielding material,
as sand or loan, is washed away like
snow.flakes before an April sun; houses,
cultivated lands, farms, forests, and
sometimes towns, are swallowed
upl The famous town of Napo-
leon, Arkansas, so noted in for
mer days, has thus been swept
away. Waterproof, once a fiourishing
town four hundred miles up the river,
has been entirely washed away since
1880, but has been rebuilt nearly mile
farther back, aud therefore on much
lower ground, but is again menaced
with destruction. In its former location
it only required levee two or three feet
high, because being then on the old
bank it was on higher land than it is
now. To-day ii is in peril behind a
levee nine feet high!
AS BANKS FALL IN, LEvEEs RISE
HIGHER.
When the banks give way far enough
back to reach the levees, they fall In of
course, and their successors have to be
built much higher because on lower
ground farther back, and wider il pro-
portion, costing vastly more. II, for
Instance, the new levee be built on land
ten feet lower than the former one was,
it must be raised to greater hight by
ten feet, and will be AZ least seventy
feet broader at its base; for the higher q
levee rises the greater must be its found
alton and its cross-section throughout.
The solid contents of levees are, in fact,
in strict proportion to the squares Of
their hiphf Men have seen in certain