The Minnesota pioneer. [volume] (St. Paul, Minn. Territory) 1849-1855, 1852-07-01


of bars at the mouth of the Mississippi and
all sediment bearing rivers is the precipita-
ton Of their sediment where the retarlation
Of the rivers current by meeting the sea
waters occurs; and any new force brought
to act upon the bars, by increase of velocity,
would be useful only until new bar should
be formed further out, where the stronger
force would he neutralized; ultimately the
present depths of the mouths would be re-
sumed, and about fifteen feet would he the
maximum depth, in a state OF nature, OH the
bars Of the best passes"
"Such,' he adds, IS the character Of the
mud upon and about the bars, that any chan
nel created there soon fills by lateral pres
sure; he whole mass being of IA doughy
consistency, no steep banks can su'sist long
under water Any excavation, or dredging
IS, for this reason, wholly truitesS. Of this
there can be no doubt"
In proof Of the last statement we msy re-
fer TO the efforts made ia 1898 aud 1889,
when, after much expense in eXcavating the
bar hy powerful steam drcdges, the MissIs-
-ippi, as usual, took The matter into It's own
hand, and filed up the ieepeneG channel
with mud during single food.
The natural depth Of The channel over the
bar Prof. F. places at fifteen feet; but such,
fortunately, Is the soitness of the mud that
ii vessel drawing eighteen feet is easily tow
ed over. or through il, by steam tugs, the
, operation requiring about ten hours. Ev-
cry such ship, therefore, scoops cut the
channel three feet deeper; but two days, or
even two hours afterwards, he says, her
track cannot be found. The result Of ex-
cavation by dredging must be similar. And
! for ih's reason Prof. 7. does not hesitate To
express the conviction ''that all efforts TO
preserve a channel Of deep eyater upon the
bar wall he found unsuccessful" BY this
we are to understand merely that TO peruia-
ment deep channel can be expected from
dredging. But MIR. For>hey is far fron,
thinking that artificial means may rot be re-
sorted 10 with the fullest success.
"EXperience shows" he tells rs, ''that
/ the frequent transit of ships which drag up
on The bottom, and the constant agitation OF
/ the bottom by steamers, keeps The mud IA
a better dissolved, less adhesive condition,
aud enables ihe currents TO get hold of and
transport The sediment, and the ships, that
come soon after, the easier 10 drag through
the mud: for this reason chiefly, lhe South
weS, Pass has better navigation than Pass
pOatre.
Upon this fact is founded the belief thar
tb5 hF-t iiIOU- u! tsit 'Iuhiiti dl1
pre>es' lUg Il proper depth would he "A well
devised system of narrowing and pioughlng g
th" bars IN the channel way;" and, IN this
mode, Prof. +. thinks navigatle channel
OF nineteen or even twenty feet might he. at
Iittie cost, permanently kept up. HIS plan,
as we understand II, would lie III the en-
p'oyment Of drag or harrow (to be drawn
hy 4 powerful steamer. of course, and lre-
queutly n-ed) having widely SET sharp teeth,
two feet or more IN length; which lo0senlng
and stirring up the inud-more eflcctuaily,
we may suppose, than ships bottom can
do 1.-THE current rni2ht h. expected 10 per-
form the rest by sweeping the particles al
once into deep water. Ii Is true this wou,u
only convert fifteen into a seventeen feet
channei; but, from the sotness OF the mud,
the remaining two or three feet would be
gained, as al present, by drawing ships
through il.
'In CONCLUSIONS, (says Prof forshey)
would state thar my confidence in the sue
cess Of such "a harrow as >k" tchsd for NJ
kpr's report, is unchanged, and tha,
should expect to reader he bar easily prac-
ucable, with nineteen OF twenty feet sells,
and this without deepenlng the water more
than 10 seventeen aud halt feet At most"