New Orleans Republican. [volume] (New Orleans, La) 1867-1878, 1874-02-04

waters une surface Ol Tue Ddrs IL very COM
monty of mud so soft that vessels of seven
| teen feet draft do pass out and in, under
| tow, when the best soundings show only
| fifteen feet water. In a few hours after
| such passage no trace can be found OF the
| channel thus made.
Il am now satisfied of the practicability
| Of closing useless mouths of the rlver, and
| thus concentrating the greater force of cur
rents upon the best bars. say Pass a-fOutre
| and Southwest Pass: but ! ain not satisfied
| that these bars would be long benefited by
the experiment. They must soon form again
at the new point OF equilibrium OF forces.
| The report, too long for literal extract,
| goes on to recommend process OF stirring
| and sitting the mud with harrow teeth !;
| these harrows to be dragged behind boats
constructed for the purpose, or the tow
boats continually plying back and forth.
| half their tri ps without tows. The engineer
predicts deepening of two feet in sound
| ings, and the passage OF boats of nineteen
| feet draft, on the Southwest Pass bar.
| AS consulting engineer of the tOwboat
company, Professor F0rsbey devised the
simple harrows, and recommended to lis
president, Mr.. JuniEs Beebe, to bid for the
| contract offered by the United States engi.
neers, General Beauregard in charge, TO
keep channel of eighteen feet for one
| wear for the sum of $1,000
The success was complete, and the pre-
| MUM paid. But the effect of this expert
| ment was lost Immediately after the work
| ended, and the channel resumed It's normal
depth Of fifteen feet. for which it appears
still to maintain an obstinate procllvlIy.
| About the year 1850 an act of Congress
| appropriated $3j00GO for an experiment
SIMILAR to that proposed by Captain Eads.
| Messrs. Craig and Rightor, men OF bold
enterprise, well backed by their friends,
| proposed to cut a channel by combining the
| water OF the Pass between jetties. Partial
success was attained as they progressed, as
| in the case of Captain Talcott's dreGgingS.
But storm came and swept away their
works and filled up their partial channel.
During the past five years the United
| States engineers have used the best abilities
known to the corps to the effort to keep
| channel greater depth over the bars at
| the two main passes, and the amodnt eX-
| pended i'll this process of stirring the mud
| that forms these bars now reaches about
| 81 200, 600. In all cases they have succeeded
| in the temporary accomplishment OF the
| effect aimed at, but in every abandonment.
| even for few weeks, OF any portion OF their
! work the channel has been lost by lateral
! pressure; and the new material brought tog.
| ward by the currents OF the river.
| It has transDired. however, that the
/ depths attained are about the limit prac;i.
cable by stirring and drer ging; that nine
teen feet has been pretty well maintained,
| and twenty feet reached, while at work.
/ But the breadth Of the bar at that depth
! becomes so great and it approaches so near
| the level Of the wide plateau outside the
bar as to render the task too great for any
! reasonable number of boats TO maintain the
channel of miles in length.
This brings the whole subject up to the
present time, without pretending to give
the details OF operations or the many in
vestigations that led to them. The report
of Generals Humphreys and Abbot, OF 1861.
| upon the delta of the Mississippi, iecites
these details TO that date; and the aD-
pendix 70 the memorial Ui the Merchants
Exchange, addressed recently TO I'll. Forty
third Congress, contains a good summary
OF the same down to the present time.
While using both these authorities. and
the yearly reports OF the chief Of United
States engineers to the latest dates. it is
proper 10 say that none of them contra.
vene the synopsis here given. And believ.
in. that we recognize il the appendix
above referred to the pen and preferences
OF Captain Eads himself. mus; say that
he has fairly stated tho situatIon aud the
eXigency before us. " bile take direct is; Tie
with LIN upon the practica bility of peraa.
nent relief by means Of jetties and Sti!riay.
AZ! :ov the following fact. and reason:
Levels.
when We reach the mouth ct :hc liver.
say az 'hc pass most available, the South
west Pass. we find the level Of the sea. Any
water arriving theg" can run but little FAR
Their. except from thc risaici.go, th. mo
Men'uIn OF one to four feet per second.
Assume the high water velocity.at bottom
on the bar. with i mean OF two feet per
second. This was the result OF the expert.
fients Of Professor Forshev in 1917. and
these were confirmed by NJ. Geo,g. Fuile.
seven years later.
This velocity will no. en-. the bar. though
the sand brought UP the inner Stop: vii! be
rolled forward. c:e. TIE crest, by ;h.. -.
loc.tv.
I'll. IA. once deposited - plastic clay for
ever. except ia the spee'a: localities whc.e
the river chanNe: may locate itself. cen.
tnries afterwards. and apply the energies
OF e greater velocity - 81: cit i Rev
chaAne!.
Greater yaiuci:ie. gre 20 be attained Only
by greater fsll. Water can not be :.Gg.!eu
except by the forces o; gravity.
The conveyance %: ietties can chi: &c.
eelera:e the velocity and growing force
ny raising the surface plane. Aua when.
by converting your jettles upon the banks.
you dam up the river. pro 'a',to, the water
VII! accept the situation. and prefer to run
out by other passes. and OVe. :Lc banks
along the channel above.
Ii follows. then. that :lie ;e:ticc. % ,,e:-
form the function expected of them. mus.
be reinforced by wings and levees extend
ing up the banks. closing such openings as
the Northeast Pass and. Wizards Jump.
etc. or if not thus assisted, the water will
pass out in the less INSTRUCTED channels.
Moreover, suppose these auXiliaries,
namely: SECURE levces up to the forts forty
miles, reared SO high that storm tides of six
feet. when thus INSTRUCTED shall not ride
over or destroy them, closing the passes
(Eortheast and Wizards, one $50 feet wide
and B. feet mean depth. the other a 20 feet
wide and 81 feet mean depth then admit
the result claimed for this enterprise. that
the channel would be cut within the .jetties
to a depth something like that in the pres
ent pass two miles this side the bar,
namely, % feet; and this would continue
till the abrasons OF the sides. analogous to
to those on the bottom, should carry away
the jetties by undermining, to make a chan
mel for the discharge of the three!old
amount of water due to the closure of the
ether outlets.
But suppose the .ietties built a mile apart
a distance needed if we would avoid their
destruction by lateral abrasion, then, inst
outside their terminus, another bar would
Immediately form, whose crest would not
have more than fifteen feet Of water. No
one denies this allegation.
The jetties must, then. be extended dis.
lance Of near 1902 feet per year, and in ten
years distarce of two and three-ffths
miles must be added to each side of our
river-canal. out in the sea. This would
cost. submit. more than the sum demanded
in Captain Eads' proposition, TO maintain
our Jetties and preserve navigation.
VIII it be necessary to add to these |
nearly insurmountable difficulties the con |
sideration that in tie normal condition the |
ailuviOn carried forward has some 400 feet |
of annual advance, and lies in crescent