New Orleans Republican. [volume] (New Orleans, La) 1867-1878, 1875-05-13
The Jetties.

In Wares Valley Momthly, q new St. Loui
publication, appears an elaborate article OF
the subject of captain Esds and the Jet
ties" which concludes as follows:
| l. Tho jetty plan is founded upon yer!
simple principle Of hydraulics, by whiv.
| the current of the river is to he made II
scOur out it's own channel. Ii the width O.
| the South Pass is 1900 feet, for instance
| reduce it to 1000 feet, and by forcing tb'
| same volume OF water through channe
less than half its present width, the veloc
| ity Of the current is thereby Increased, and
| the water is made to DO its own dredging
This principle has been successfully ap
| piled Thousand times.
| 2. 1t is proposed to narrow the channe
by sinking Rats of willow brush in two
parallel lines extending far out into thu
gulf, until broad and permanent founda
ton is made extending up to within few
| feet of the surface at cob tide, and ther
build upon this foundation dikes Of solid
masonry high and broad enough to contine
| the water at any stage. i.
This work accomplished. will the result
followi Capain E .ds has made personal
inspection of the jetties vt the mouth of the
Rhine, the RhOne, the Po and the Danube
| latter. confirmed by . partial investigation
| of the others, he concludes that the channel
OF the Mississippi can ber deepened in the
! same way.
But there are serious differences to be
noted:
l. The Black sea, into which the Danube
emptiee, has no app ecisble tides, while the
feet twice in every twenty four hours, which
must necessarily affect the current Of tho
channel to some extent, it it does absolutely
| reverse it during the rising tide.
2. The comparative specitic gravity
of the two waters At the mouth If the
Mississippi is much greater than ut the
mouth Of the Danube. 1t the river water is
higher than the gulf water. the tendency,
on yer ical contact, will be that the lighter
water will sbelve ITSELF upward toward the
surface, and the heavier water wedgesitself
downward, and underneath the lighter. A
Counter current will he forned to such an
extent that the securing process of the out
flowing current will ba materially dirniu.
isbed, if not altogether prevented. The
greater density OF the salt water will carry
it to the bottom, and tie greater pressure
frrm the gulf hold it there, causing the
lighter frert water TO how to the surface
and reach the gulf vithUnL any appreciable
. effect upon the bed Of the channel; except,
il might be, to send down it's perpetual CON
trIbntiOn of sand aud sediment, thus ex-
tending the fast forming delta
3. The river havln;s more tina one mouth,
or outlet, TO the gut. II may be that the
sttorf to cOntine the current to y narrower
channel in one Outlet-whirh will have the
effect of an Obstruction-WHl increase the
discharge through the other outlets, instead
OF increasing the velocity of the cnrrent
through the narrowed channel After the
current is checked up, Or stopped, in one
direction, there will be but little head or
pressure of the on coming volume against
the Ob~tf uctlOD, unless the bed Ut the
river above the delta is much highes than
At the month, which ia not the case.
The btd OF the river as far up
as New Orleans. and, perhaps, higher,
is from sixty to one hundred, feet be-
low the surface Of the gulf. What prevents
the heavier salt water OF the guilt from
wedging itself unGe er the fire all water of the
river aud underlying he river for all Of
this Gisfancea Has any one ascertalned,
by actual experiment, whether the river is
not salt water at the hntiom opposite New
Orl-ansi Shonld this 10 the case, then,
II must DO supplied from the guilt,
which will have the .9ect OF coun.
ter current. This h7po aesis is strength
ehed BY the constant acfion Of the
tides. How could 1t ue 1Enrr~Ises Ii 50,
then the current ot fhc rl,4r must be en-
tlrely superficial, having & b-d ii compare
lively dead water un0er yiBg- t. The fre-
qdent storms upon the g"l.. w1lch rolls its
heavy saline wayes tar Up .,p 4rd the Cres
cent City, must contribute 20 his under
lying bed. as the neal el water will trd
lie way TO the bottom after the forces |
that kept it upon the s1rt4.e nave been
re emoVed and the uied has ceased.
The Mediterranean, with its deep bed,
connected by narrow aid @As low straits |
wiFn the Atlantic, at Glaraitar presents a
ph"nOhenoh noS sitogetnec unlike that !