The New Orleans crescent. [volume] (New Orleans, La.) 1866-1869, 1868-06-26
Description OF the New Mss.issiPpi United
States Dredge Boat.
We copy as follows from the Boston Advertiser

We copy as follows from the Boston Advertiser
of the 18th:
After series Of experiments, Brig. Gen. N. d.
McAllister became satisfied that the true method
Of opening channel through the bar of the Mis-
sissippi was To construct peculiar dredxe boat
with the most powerful engines in order TO stir
up the mud necessarily, and thereby cause the
current 10 carry il into the gulf or into deep
water. He submitted his theories and plans to the
war department and they were approved and
recommended to Congress, which promptly
passed an appropriation to build and maintain a
steamer Of the description indicated.
The Atlantic Works, Boston. got the contract to
build this naval nondescript- first vessel Of the
kind ever made or needed. II is just finished and
will sail for New Orleans to day.
II Is long, narrow boat, somewhat like ferry
boat, with screw propeller at both ends, with
rudder at both ends with plothouses al both ends,
with engines at both ends, and with machinery all
over and under and through 1t. II Is 100 feet
long, 30 feet wide, 20 feet deep and $50 tons bur-
den. Its name is Essayons.
Essayons TO describe Ii:
The propeller in its stern is driven by the engine
aft, which Is direct acting oscllsting engine of
forty inches diameter and four feet stroke. The
reader unfamiliar with the force indicated By these
figures may possibly Ike 10 know that IL Is the
rather indefinite quantity known as 800 horse
power, or the force that is required to send
vessel of thousand tons across the ocean at the
rate of nine or ten knots an hour. Forward,
there are two engines Of the same kind and cal
ber to drive the fore screw, which is Of fourteen
feet diameter--or two feet larger than the stern
propeller-and which extends two feet below the
keel of the vessel and Is intended to stir up the
mud on the bar.
Now let MS see how she acts.
With her prov up the river she strikes the bar,
and the stern propeller forces her into Ii at the
rate Of five miles an hour. Her powerful for
ward engines at the same time are turning the
mud screw, which raises the thick sediment and
holds it in solution until the current washes IL
away. II there Is not too strong tide, q huge
rake fastened to boom at the stern, is let down
two feet below the level of the keel-or to the
level of the mud.screw-thus preventing the mud
from falling back, and at the same time renewing
| the process of agitation begun by the action Of
the forward propeller. The shaft or handle Of
this rake is fourteeni feet long, and its twenty
| appointed teeth are each foot long. After
forcing its way through the bar, the steamer re.
turns as nearly possibleby the same track with
out turning-the mud-screw, on this trip, driving
| the boat and dragging behind II rake OF THE
same description as the one just noted. By this
time channel of fourteen feet in Widths opened
After trips enough. back and forward, TO render
this new channel secure have been made, the boat
is sunk two feet more, and the same process is
newed. Then il Is sunk two feet more. and again
two more, until twenty feet Of water flows over
the bar. The art Of sinking y is effected by let
Ting water into one or more or all the six great
tanks or compartments into which the hull OF the
vessel, not otherwise appropriated is divided
for this purpose. The water is let In from holes
at the sides and when the task is done il is
pumped out by four engines OF ten-inch diameter,
| constructed for this special Office.
This makes seven distinct engines In this vessel !;
but there are still more-one q steam pump for
filing the boilers when the ether engines are at
rest and steam " winch for hosting coal, hand
ng the rakes, and other general purposes.
When the vessel is sunk TO make channel
twenty feet deep, its tanks contain six hundred
tons Of water. When 1t is ready to go 10 ses-so
heavy are its machinery and boilers-it needs only
forty tons of non ore, besides her COAL to ballast
her.
1t would be easy enough to puzzle the land
faripg reader by technical description Of the
different parts Of this curious steamer-this nauti
| cal tooth brush-but as you would understand II
as easily as letter from our Anson's long tailed
| companions, / refrain from an infection so I'M
generous.
These are the notable facts about II:
Ii carries more machinery than any other vessel
| of its size ever built. 1t is made as strong as
it. The hull sns ETHpsh s1a sss o Sss
by Curtis Smith & Co., and every part OF the iron
| work and machinery was manufactured at the At
| lantic Works. She was constructed under the
personal superntepdence OF ID. w. Payne Of the
engineers, In behalf Of the government, and J.
W. Marshall, engineer, and |. N. Lathrop, master
machinist of the Atlantic Iron Works on their be.
I half, from the plans add specifications OF Gen.
McAlester, who has charge OF the improvements
| for the mouth Of the Mississippi river.
She has made q trial trip in our harbor, which
| was entirely satisfactory to the builders and the
| officers of the government. Saturday before last
she steamed down Long Island and tried her screws
and rakes on the deposits near its shore, which
are of similar character to those of the Missis-
sippi but much more solid and tenacious. The
| dredging machinery worked successfully. made a
channel of three feet In short time, and the pro-
polling machinery, without any special effort, took
tie vessel back TO the wharf-a distance OF nine
miles in less than an hour. A trip outside, to
learn how she would act in sea way, was equally
gratifying In its results.
This vessel csst nearly quarter Of million Of
dollars and il will cost from s75 900 to 500 900
year TO run her. She needs So persons to man
her: chief engineer Josiah l.. Folsom, OF East
Boston,l first engineers, others, 6 fremen, 8
coal passers, 2 mates, stokers, cooks and sea-
men, besides, of course, captain &c. Il. Putnam,
| Of sslem.)