The Sun.
London, England, 1853-05-21 00:00:00

GOVERNMENT WORKS AT; KAYHAM.

PLY-31.0-OTH, MAY 19.
These important steam works a re fast approaching
completion, and a considerable step 'n advance has been
made this week by floating four of tl te new caissons into
their places. Keyham lies on the m srgin of Harnoaze,
to the north of the gunwharf, which almost adjoins the
dockyard at Devonport. The area of 'the works is simi-
lar to that of the Dockyard —aim at 75 acres. The
western side faces Hainoaze ; on then north is Keyham
Lake, and on the south Moon's Cov a. It is thus sur-
rounded on three sides by water. ' rile east is bounded
by a high wall, which forms one side ; of the road leading
from Devonport to Bull Point—t he new Government
magazine for gunpowder. The ma; ..n entrance for ships
is to the southward, where the depth is 20 feet at low-
water average spring tides. The on trance is splayed off
on both sides to avoid damage h y collision from the
strength of the tides, which run occasionally with great
force up and down Hamoaze. The foundation of the
entrance )ock was laid in 1845 by Loi A Auckland ; it is
36 feet deep at high-water spring tides . This lock leads
into the south basin, which covers seven acres, being 630
feet long by 560 feet broad. In connection with it, run-
ning to the eastward, are three large doe s, two of which
are 310 feet, and one 389 feet long. The basin, dock-
wharf, and other parts are formed of fine-wrought
granite, from the quarries of Messrs. I 'reeman, and with
the other works are skilfully executed by Messrs. Baker
and Son, the eminent contractors. TW'O powerful cranes
by Carmichael, of Dundee, stand 40 feet vertical from
the coping of the south basin ; they can plumb 35 feet,
and their power has been tested to the extent of 40 tons.
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then pass her into the charge of the mister shipwright,
who will put her into dock and repair her hull. She
will then be sent through the south basin into the north
basin, which is intended to be 700 feet -Jong by 450 feet
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riggers, and painters will do their work. She will then
be coaled, and will depart by a western communication
from Hantoaze. The north basin is provided with a
gigantic crane by Fairbairn, of Manchester, which is to
be tested to the extent of 60 tons.
Mr. H. and M. D. Grissel, of the Regent's Canal
works, have supplied the Government with five caissons
for closing the entrances to the docks, &c. These ma-
chines, which seem well adapted for the purpose, are con-
structed in a peculiar manner, invented by Mr. Scamp,
assistant director or works at Somerset-house. They are
shaped something like a vessel, with two bows or stems ;
but the stems and keel, which are of wood, are perfectly
straight—the keel horizontal, the stems inclining a little
from the perpendicular. They fit into a groove of gra-
nite larger than the timber—the exclusion or retention of
the water being obtained by the force with. which the
wood is set against the smooth and equal surface of the
groove. The caissons are made of iron-plate, half an
inch to three-eighths thick ; besides the upper deck they
have two water-tight decks, which divide the machine
into three compartments; these divisionn form the pecu-
liar characteristic of the new caissons. The lower com-
partment is for the reception only of brick ballast, suffi-
cient of which is placed in it to sink a caisson, say to a
depth of 17 feet, when it would float at. discretion. The
middle compartment, seven feet high, is furnished with
an inner and an outer sluice, which, when open, do not
affect the flotation. The upper com partment is fitted
with several tanks, and when these are' filled with water
from above the caisson is sent down rapidly into its
place. When the water in the dock is higher than in
the basin, the sluice on the dock side is opened, and the
other closed and vice tersd. By this arrangement acci-
dents through unexpected buoyancy, which have
occurred with some caissons, are avoided. One man
can in a very short time float a caisson of the new con-
struction ; by turning a wheel a mitre -valve is lifted, all
the water runs out of the tanks, a.nd the ponderous
machine can be easily removed in any direction.
The buildings at Keyham are progressing. The
entrance is near the south-east corner, where a station
for 50 policemen and a guardhouse for the military are
in an advanced condition. At the head of the docks is
a large fireproof smithery, with lofty granite chimney
shafts at each corner; this building, with the fit-
ting shops' and sheds further on, is complete. The
principal erection, the foundation and plinth of
which is only laid, will be the quadrangle to the
east of the north basin ; the quadrangle will contain
stores for the engineer, and for the copper, brass, and
white smiths, and two boilerhouscs ; tbo centre will be
occupied by the foundry. It is designed to form a boat
basin and boathouse at the extreme north, near Keyham
Lake. On the highest ground, near the eastern road,
there is a large salt water reservoir for feeding the cais-
sons, &c., and near it will be constructed a reservoir for
fresh water. The drainage of the works is ingeniously
arranged, so that water can be thrown from one dock
or basin into another, however distant. The engineer-
in-chief is Colonel Williams, of the Royal Engineers,
and the engineer in charge of the works is Mr. R.
Townsend, civil engineer. The buildings are from de-
signs by Mr. Scamp and the department of the Director
of Works. About one million sterling has been ex-
pended on Keyham, and it will require some 300,0001.
to complete the establishments. Large as is this ex-
penditure, the cost is said to be less in proportion than
that of other similar establishments. The docks at Key-
ham cost each about 45,0001., while on one at Sheerness,
not so large, 125,0001. was spent, owing partly to the
difficult foundation. The west dock at Woolwich,
which is only 300 feet long, cost 90,0001. The new
caissons at Keyham cost, on an average, 4,5001. each.