The New York herald. [volume] (New York [N.Y.]) 1840-1920, 1875-02-04

decided advantage over the Fort St Philip site.
long, passing through q country OF which no part
10 more than three feet ABOVE tide, and much OF
its route hes through shallow lag0ons. At two or
three ieet below the surface the delta at and be-
low the site OF the canal Is everywhere OF blush
mud or clay into which pole can be thrust 6y
wave action mas siited ont and lett the coarser
sand IN thin layers, and such strata perhaps from
the same cause. are found elsewhere In the delta.
Borings 100 ieet deep show the same cay. becom-
ing more compact, anu mixed with occasional
river is OF feet above the mean level OF the Gull
and nigh water feet above the same plane. IL
is estimated that nigh water of storms at Sable
Point Is sometimes ieet above mean level or the
Gulf The lock Is therefore planned Tor iir Of
feet; but as the water at Sable Point will never
OF the canal, except for lew hours during violent
storms, no provision Is made Tor locking down
10 currents r1snns In either d
recticn through the canal
For details as to plan OF canal and estimates see
n.-DEEPENINs NATURAL OUTLET
The methods which have been proposed for
mouths OF the Mississippi are two:-
FnSt-By stirring up IN some way tho material
Of the BAR SO that the current shall sweep It away
Secondly confning a mouth OF the river by
jettees on the par 80 that, aided II necessary by
scour channel through the bar, and TO MAINTAIN
1t when once formed
Judging rom the results thus lar obtained, the
Board Is OF the opinion that no admissible ex-
penditure OF money can permanently maintain BY
the stirring process depth or twenty feet az
mean low water at the mouth OF the Mississippi;
and as they do not consider this an adequate
depth they deem the rrst process named mad
In considering the method BY jetttes, 1t may be
well to state the iacts on which their application
at the mouths or the mississippi y based.
1t will De seen that each pass through the greater
part or It's length has o nearly constant width,
our that 1t wtdens toward ltS bar, SO that on It's
outer est 1t has several times ordinary wioth
while Its depth IL less IN something like the Same
the following :-rhe river water as it approaches
the bar Is somewhat above tue level OF the Gulf,
sc 70 sas mus
which makes the fresh water rise over 1t on q
slope that Is sleeper The velocity OF the river
water Is less. ms Trimmed sheet OF water forms
Its own banks as the bar moves out TO sea; but.
as in this wide, swallow stream the friction Is
great near the banks, deposits begin there, the
stream Is narrowed and deepened and IN time
assumed by tue portion above, which allows the
water to pass with least resistance. To-day, while
there are OUT seven ieet OF water on the outer
$4,000 feet from the oar to so feet OF water
above the bar, and 1t follows II the bars progress
same as Tor the last InTty-slx years about 100
feet per annum). that 100 years ago the outer
crest OF the South Pass bar was where now there
ts deep caannel. AS tue bars move out to sea
the river is, then, all the time erO0icg channel
OF the CHARACTERISTIC deep water cross section be-
to AID aud hasten this erosion. II. starting
from point II pass above IT'S bar.
which cs 40 cops e 81
nave the width all the way TO deep water 1t now
has at tho starting point, we shall be helping the
would ultimately take, ana oy aiding 1t, II neces.
Sary. b. dredging, should be able 10 reduce ct
This plan is then adopted Tor the Improvements
OF natural outlet-nainey, to begin parallel dikes
a. me 81 are 80
the bar to 80 ieet water outside unless the depth
10 obtained before the dikes have reached the 80
between the dikss TIL the waterway between
them everywhere has the same cross section az
e. g odag su sHsoR %:as
The Board considered the question OF limiting
the waterway to the GROSS section OF 30 feet max
parallel dikes In view Of the lack Of experience
zee II saOaS SSoRs s d 81 as
was deemed advisable to adopt parallel dikss %
Tss @ Of f % "a: s.sa
the par which win form 81 the sea END Of the
which 1t Is desired to MAINTAIN.
ment Of ono q Inc nstursI outlets. Il remains 70
AZ On that one. AZ tne Improvement Of any WI!
sso SSs SS 1sSs Ss al and A'
sl9srsa are tEs santh AND so1thwsst 49,. ..
700 FEET, that Of Southwest Pass u about l,loo.
but. Il the opinion q the BoSrd the g south Pas;
when improved will be adequate TO the present
for o. Is.
maintenance OF che works for the Improvements
Of the South Pass IL $3.50 ITO. and for soutowess
Pass is Sl6 053,l 2A II 10 assumed that the South
west Pass bar advances about three times az fast
q. the South Pass bar.
mucn greater cost Of improving the larger pass
would not. IN the opinion of the Board. De war.
ranted either BY the somewhat greater ease OF
entering 1t In storms or or navigating tt when
once inside. The former Is 1913 miles long, the
latter being IS miles, and Is lengtnened only
about one-third as last as the latter.
The cost or improving Pass pOutre would also
be Tar greater than Tor South Pass, without
advantages SUFFICIENT to justify the increased
WORKS lor its Improvement which would require
at least Two Or three years for their execution.
Board II, therefore, OF opinion that II any natural
outlet Is improved 1t should be The South Pass.
has an ayerae wdt Of o Is ami
minimum interior channel depth or 20 ieef. 1t Is
ll,s0O ieet from the 30-loot curve inside the Pass
across the bar 70 80 Ieet outside. The minimum
depth on the bar IL ieet. 1t discharges at lis
mouth about 1000 cubic Ieet OF water per second
and aoout 22,ooooOo cubic yards OF sediment In
suspension per annum. 1t has shoa at its head,
VITA minimum depth on u In channel OF II feet
o For me improyemsni q Of the south Pass the
structed OF brush, iascines and stone In the same
general way as those used BY Nj. Caland o. the
mouth Of the Mas.
Tne.e dlkes should begin al the two banks OF
tie Pass about 1850 ieet below the South Pass
lighthouse, where the river has width OF nearly
900 feet and maximum depth Of 30 leet they
should run In straight lines, parallel TO
each other. In the direction OF the
Pass, TO wheie the water 10 20 feet deep
outside OF ne bar, provided should be necessary
10 carry them 30 iar TO secure 50 leet depth. Tne
dlkes or the drst 100 ieer should ba 10 ises vice
on top should tnen widen gradually u 70 feet in
further distance Of 2osl iest; should then sradu.
ally widen to so teet which ID TO be the width In
80 eer OF water. At present THIS last length would
be about 2760 ieet, and the total length Of each
dixie 900 feet The hrst lilo feet Of the bikes to
have side slopes Of two.tnirds two vertical to
three horizontally, the rest to have SHE slopes OF
heath mat depth slopes Of ons.haif. The top Of
tno dikes 10 be rounded aud pavod, the crown
rising to hlall water OF spring tides.
The question OF tho average annual expense OF
proonGiug the ettles 10 very serious ono; 1t De.
Ponds On The annual advance OF the twenty-five.
loot curve, that dep'h being required. At present
the muddy water issuing from the South Pass
spreads OUT ~ some what VI IAN .snape, tue nan.
49, I've -