The Sun.
London, England, 1859-03-24 00:00:00

THE NAVE

The Cadmus, 21, screw corvette, in dock at Cha-
tham, is nearly ready for the pendant, and will be •
undocked during the next spring tides.
Her Majesty's sailing frigate Severn, 50, is to be
taken into dock at Chatham dockyard, for the pur-
pose of being converted into a screw steamer and
fitted for sea. The Severn was built at Chatham,
and ever since her launch has been attached to the
ordinary at that port.
In consequence of the pressure of work at Cha-
tham dockyard, consequent on two screw line-of-
battle steamers and three frigates being just laid
out, the whole of the smiths are employed from
six in the morning until eight at night. The 300
additional shipwrights and the other extra artisans
have all been entered, and all the departments are at
work in full activity. It is expected that a large num-
ber of additional labourers will shortly be entered,
the present labourers, and also all the convicts em-
ployed in the dockyard, not being sufficient for the
requirements of the establishment.
The Mersey, 40, screw steam frigate, Capt. H.
C. 8., went out of Portsmouth harbour at
noon yesterday to test her speed at the measured
mile in Stokes Bay. The results of the trial gave
great satisfaction both to the contractors for the en-
gines and the Government officials on board. There
was not the slightest appearance of " priming of
boilers" or " heated bearings," so common in first
trials. This is all the more extraordinary as the
Mersey gives the highest return of indicative horse
power of any ship yet tried out of Portsmouth har-
bour.
vas
nominal power is 1,000 horse, but on the
trial yesterday it as worked up to the enormous
power of 4,000 horses. The average results of speed
obtained in the four runs at the measured mile gave
13.290, or better than 131 knots ; pressure of steam,
20 ; vacuum, 24 t revolutions, maximum, 56, mean,
551 ; diameter of screw, 20 ; pitch of ditto, 29 ; im-
mersion 6 in. ; force of wind, 1.0 ; direction of wind,
N.W. ; draught of water forward, 20 ft. 8 in. ; do.
aft, 22ft. 7 in. ; coals on board, 850 tons ; consump-
tion of fuel at full speed, about 140 tons every 24
hours ; thermometer in engine•room, 62.0 ; ditto,
stoke-hole, 100.0 ; ditto on deck, 52.0 ; length of
stoke-hole, 68 ft. 10 in. ; breadth of ditto, 10 feet ;
number of fires, 32. The tops of the boilers are
three feet under the load water line, and another
important feature is, that the engines are placed
abaft the mainmast, which may in consequence be
stepped in the keelson. Three auxiliary or "don-
key" engines are fitted on board, two to supply the
boilers, and the other as a steam fire-engine, which
is fitted with a 4 inch copper pipe from the ship's
side, under the beams of the orlop deck, fore and
aft, with seven 21- in. pipe branches up through the
lower and main decks, each branch with two nozzles
to screw on lengths of hose, and four branches on
to the upper deck, with the same means of screwing
on hose lengths. In the event of a fire breaking
out in any part of the ship, it is only to turn on the
main cock at the ship's side, set the steam fire-
engine at work, and any amount of water can be
instantly conveyed to any part of the ship. In the
event of fire breaking out in the orlop or lower
decks of the ship during action, the engineer and
his staff could at once deluge the part with water,
and extinguish any fire without the necessity of
ringing the fire bell and calling the crew away from
their guns, or creating the confusion and alarm
which would ensue under existing regulations.
Should any portion of the pipes be shot away, turn-
cocks are fitted so as to turn the part injured off,
and not impair the efficiency of the rest. To make
the engine complete for the purposes it is intended
for it should have a small boiler fitted for its special
service, and not have to draw upon the main boilers,
as, in addition to its usefulness as a steam fire-
engine, it also, by an ingenious and simple con-
trivance, hoists all the ashes up from below, pumps
out bilge-water, and draws water for washing decks.
The Mersey's armament consists of, on the upper
deck, 12 8-inch pivot guns, 10 feet 6 inches long,
throwing a solid shot of 681 b. Main deck, 28
10-inch guns, 9 feet 4 inches long, throwing hollow
shot of 841 b. The total weight of the guns (with-
out carriages) on the upper and main decks is
178 tons 3 qrs. 2 cwt. A broadside from her would
give to an enemy in action 1,6521 b. of iron. The
Mersey has more stores yet to take in to nearly the
extent of 250 tons. The ship appears to have but
one serious fault, and that lies in her steering appa-
ratus—in the position of the after sheaves for her
wheel ropes, which are placed in direct opposition
to all mathematical principles. We understand that
all steamships are in future to be fitted with steam
fire-engines on the Mersey's plan.