Memphis daily appeal. [volume] (Memphis, Tenn.) 1847-1886, 1883-03-04
wBAr As rag UsE OF LEvEEss


that as sf,sp- Ls--.-seEed OF late, especially
BY persons who never saw one. Their use IS
10 confue the waters of the rivers on whose
borders they are constructed within then
channel, go as to prevent overflow, and also
10 hasten the passing of OF the supeifuous
waters. How over h0w is prevented by high
banks everybody understands, but many
have not r. hected how the flow OF the water
is fastened. Let the reader, with little
clay, construct a channel, say OF three or
four inches broad, along piece OF ground
rising very slightly on each side the channel.
Let him then pour water gently into the
channel and observe the speed at which the
water is delivered at the end. Having done
this, proceed to open two or three oritces
along the sides Of the channel, 30 that some
of the water, instead OF flowing directly TO the
discha rgiug placs will pass out at The sides;
then, when the decrease of the amount OF
water in the chsnnel has lowered the sur
face. the water that had escaped at the sides
will how back into the channel and 60 puss
off at the end. While it does so it will not
be with the same velocity as in the first in
stsuce, for two reasons. First, time will be
taken in the outflow from the sides and the
rsturn inflow. Second, and what is the most
important thing in the levee question, the
water that runs down the channel being
maintained by the sides of the channel to a
certain hight, the weight of the water SO
sustained pushes forward the water immedi-
ately before it, and so hastens the current,
and consequently the delivery at the end oil
the channel. Now, take the case OF the
channel with the openings in the sides. The
water, instead of being held up to the hight
sustained in the former cases, spreads
out sideways; what remains in the
channel, not having much pressure behind
it, flows off deliberately, and as its surface is
lowered the water at the sides passes in again
and it also passes off deliberately. Had the
sides of the channel in the second expert
meut been here and there spread out, so az
to allow the water to spresd sideways over
the space, in that csse also the water, having
room TO spread laterally, will not be raised
to the hight required to produce important
comparative slowness The reader can fol-
low all this in his mind as we detail it, and
he will see that the wider the space on which
thu water lies the shallower 1t will be, come.
oueutIy the pressure will be Light and the
how slow, Decrease the space occupied
and the water will be deeper; the deeper
the water the stronger the pressure
cons, quentIy the quicker the no"
When the waters of the Mississippi
can spread out sideways, here and there al
wide places in the river, the flow Of the water
will be decreased, because wide places are
.hallov places. When the wster can rur
over the banks, cover the neigh boring LAND
and a. the surface Of the river sinks, foV
hack again. then the current will be com
naratiyely slow. But when the waters or
kent within the banks by willow MATTRESSES
mr. nv leyees, the waters are sustained at
sufficient hight to produce pressure, whiol
impels the current forward, hsstens the dis
charge. aud so either entirely saves from foo'
or r, duces its des'ructiveness. Another val
uabIe result is also secured by thiE means
the Wig orous flow Of the waters causes then
TO scour their bed, and 60 deepen it, and ID
more the depth the more, as shown above
the pressure and the speed of current
When the surplus waters have passed
the Wa ters retire to the center OF the channe
and there pass of no quicker than at ihel
usual rate. The bed having been secure
out, the alter is deeper at slow water" th'l
before the securing out, so that the plan Q
con6ning the river within its channel nc
only pours the water off more rapidly
high water, but retains deeper water at lo'
water. Here the attentive reader will intel
pose an objection-if the speed OF the waite
is proportional to its depth, and consequer
pressure, the water In the scoured-out be
must run off more rapidly and leave 10
water at as low point az before. Hel
comes 10 one Of those beautiful compensl
tons always so striking in nature. II
the and Of n cane on the table, as yo
raise your hand the slant OF the car
ia greater, as you lower it the slant Is les
but the END the table neither rises N
falls. Ia -As ZANE wpy the end OF The bt
of the Mississippi rive. is al the sea and r
mains there, tbs bed of the river slsnts :
ward that end; securing the bed deeper
~fxeie~osiAg- tha md that holds the cane,
"A I'd me-. ~ slant less. The dr. =