The Express.
London, England, 1859-07-28 00:00:00

THAMES GRAVING DOCK COMPANY.

A large company connected with the commercial
and scientific world assembled yesterday at the Victoria
Docks, to witness an experiment serried out tinder the
swine of the Thames Graving Dock Company for seating
the efficacy of Kr. Edwin Clark's patent process of raising
ships for the purpose of examination and repair by hydraulic
pressure. tinder the old plan of graving, careening, or re-
peiring docks it was necessary toexcavate each dock toadepth
sufficient to float the largest ship intended to be repaired,
and to construct at the entrance of each dock a flood gate,
or pair of gates, to keep the water out. For ships of the
size now in common use the depth of a repairing dock must
be about twenty-four feet, nosing a heavy expense for exca-
vation and retaining walls of masonry, independently of tho
oust of the tidal gates. An entry into docks of this ocostnic-
non Is effected at, or soon before, or after, high water. The
gate is than closed; and at low water, on a tidal sea, the
water is allowed to ran out until the chip is kit dry tor
examination er repair in • sort of pit., always damp, and,
In winter, soon dark. In tideless mu a graving dock meat
be emptied by the slow and expensive proat of pumping.
The new process obviates there difficulties and delays. A
floating stage or pontoon is placed in a basin or waterway,
and the vessel requiring examination or repair is floated upon
it, and by the application of hydraulic pumps the stage,
with the need upon it, is raised, and becomes a working
platform, upon which :the vessel, lifted up high and dry as
in a dry dock, may be oaWked or coppered or repaired as her
necessities may require. The hydraulic lift conflate of two
parallel rows of sixteen cast-iron ociumes, each 6 feet in
diameter, and 60 feet In length, sunk into the ground,
under the water, about 12 feet. Thais columns are 20 feet
apart in each row, and the clear space between the two rows
Is 80 feet. Each column contains a hydraulic press 10 inches
in diameter, and of 26 feet stroke, the top of the pees being
at the ordinary level of the water. The ram of esch press
carries • small erase-bead, from which ars suspended,
by mama of dweandiag rods, two wrought-iron orders
60 id in length, which extend entirely acmes the
dock to the conespcmding minion and press on the oppo-
site side. There Is thus • eerie' of thirty-two suspended
girders extending eatirsly across the dock ; and when the
are lowered, lying at the bottom of the dock in 28
=water, these fovea it largo wrought-Woe gridiromwhich
by means of the presses may, with a vessel spin it, be mimed
out of the water or lowered at pleseure. The vessel to be
docked is not raised directly upon the gridiron, bat upon a
wrought.iron pontoon, proportioned to the size of dm .hlp to
be docked. This pontoon ts first placed on the gridiron, and
sunk with it to the bottom of the water. Then the snip is
brought between the columns and over the pontoon. and a
50-horse engine working the hydraulic preeees, rake. the
whole pontoon together. At this steep of the proceedings
the pontoon empties lied, of wet, r through valves pro-
vided for the purpose; the valves are them closed, and the
gridiron being again lowered to the bottom, the pontoon, with
the vessel seated upon it, is left afloat on the midget.. The
shoring of the vessel (a work of difficulty and coat under the
old plan) is accomplished by large moveable fames or rliding
wedges, which, while tinder water, are crown into clues con-
tact wOh the vessel, so that the sits on a huge timber clads
without poesibility of being strained. Lulea than 40 minutts
• vessel drawing 18 or' 0 feet of water is thus left silent on
a shallow pontoon, drawing only 4or 6 feet. At the Victotia
Docks the lilt condom of 16 whinine, which give • working
length of more than 340 feet. Perfect horizontality while
lifting Is secured, by arranging the presses in three inde-
pendent groups. According to the statement of the company,
the general sdventages of the new system may be summed
up under the following heads ,-1. Independent of tideP, end
at ill times, whether by night or by day, yees•ls of the largest
dimensions. whether empty or boded, may be raked out of
the water for examination. 2. The maid thus raised is
transferred by gestation, without rails or slip, to suitable
docks for its repair, where it lies high and dry on a conve-
nient timber platform, on the Gams level as the repairing
shop' with which It is surrounded. In painting vessels,
the free exposure to the air is a most important advantage,
3. One; dusk lift or apparatus for raisin ts sufficient for
docking an unlimited number of vessels. 4. The method
employed in raising and transporting vessels renders it im-
possible to damage them by any unequal stratus. 6. The sup-
port of the vessel by mist-iron columns affords Mena of con-
structing such docks either in open water' in tideless sea, sr
in slmost any locality, independent of the diameter of the off.
As confirmatory of this statement the experiment of yes-
terday was a make moms. The vessel experimented upon
was a fine ship of 870 tons register, and some 1,200 or 1,600
tons burden, the Iron an Aberdeen clipper which wee
floated upon the step, 'and by the application' of the to
draulic pumps was in about twenty minutes brought up oat
of the water, and handed over to the manipulative ingenuity
of soma two or three score of shipwrights, manipulate add
coppetemiths, by whom her defects were in a very few
minutes
wvehiriar,thisanadmbyipidathis treraprobsh dock cog° ivin °re

......_
r.
Amon the company who were premed to wereitusig,tle
Among
experiment, which was eedarsilyenecesdo/. w Sk ardx
Paxton, Btr S. M. Peep, Lord Clarence Paget, Lord C.
Hamilton, mew. M. Long, 31 P.. Hums, M.P.
, Cratahlay,
B. R. Stanley. Coeds, Rad, 0. F. Young, Cragehaw, J.
Claim. Lee Stevens, A. &ea, Gwen' Wylde, CeL Bums,
POW Le Neve Fender,