National Republican. (Washington City (D.C.)) 1872-1888, 1884-09-05
THE HYDRAULIC DREDGE.
The New Machine for the work on the PotC
mac Flats.

A vessel in course of construction at the
foot OF Third street southeast, is attracting
much attention and various theories as TO its
ultimate destination and use arc advanced.
Its lines provide for n hull fity feet across and
100 feet long and twelve inch timbers are
used to form the She'll" The other timbers
are in proportion and some delay has been en-
porienced in the work, owing to the difficulty
of procuring beams of the necessary strength
in this section.
The massive hull is being built as the foun-
dation upon which to construct the first
hydraulic dredge ever made in the east. 1t is
to be used by Messrs. Benson Il McNcc, of san
Francisco, the contractors for completing a
part of tho work on the Potomac flats. The
patterns for the machinery, which alone cost
$1,000, arrived in Baltimore yesterday from
California. The whole machine will cost,
Tho work 1t is destined for Is the dredging OF
q million yards of river bottom and deposting
II ON the flats at price oil ~ cents per yard.
The contract Just completed was at u cents
per yard and the scope of the work possible
under the sjO0,0OO appropriation will be pro-
portionaCly enlarged
\ brief notice OF the mode of operations by
this new process of submarine excavation was
nude at the time the contract was awarded.
A REPUBLICAN, reporter yesterday met Col. Won
Schmidt the inventor OF the machine, who is
here prosecuting II claim for S2,UOJ,00O against
the government for an infringement of his
harbor rock blasting patent He is not inter.
csted in the present contract, Benson x McNce
having bought his patent rights for most oi
this country, but has Just completed II large
undertaking OF a somewhat similar character
in California, where he filed in 400 acres Of
marsh, which made hard ground He there
dug out ten cubic yards u minute, making
5000 yards each month, working ten hours .
day. Here 1t is understood that the work will
be carried on continuously, night and day,
electric lights being used when necessary. II
Is not believed that the machinery Will be
ready under ninety days, but when q start Is
made progress will be very rapid
A horizontal wheel, with three plows at
| tached to its edge, is operated under u hood on
| the river bottom. This Is operated through d
telescope tube and gearing. Just above the
| pillow, and inside Of the hood is the suction
| pipe, twenty inches In diameter leading
| through powerful pump driven by 900 horse
power engine. The exit pipe, of the same
dimension, is conducted over pontons TO the
fats, where the pipe Is, carried TO the most
available point of distribution. This pipe Is
connected together by ball and socket joints oil
| rubber elbows, according TO the requirements
of the situation. The speed of the plow and
pump have to be adjusted to suit the character
| of the ground, much of that expected to be
| found here requiring but little If any mcchan
| ical disturbance 70 allow of its being drawn w
| by the pump. When II bauk of boulders Il
| encountered, other means will have TO be
| adopted to raise them. though the pump will
handle any stone that can be taken up by the
pipe,
| In commencing operations at given spo
the machine is first anchored by means Of 9
couple of heavy beams, called "spuds," lie
down through The bottom of the boat. Tn,
| pillow and suctiot-pipe are operated from tn,
| end OF beam, which sweeps across the sterr
of the boat, cutting a swath Of sixty feet witt
| a vessel of fifty feet beam. The bottom Of the
river can thus be planed smooth to any ordi
| nary depth and for any length and the debri
1 VnsNfVN HtEtn ant
ton to settle itself by spreading into a smooth
| hard surface.