The Sun.
London, England, 1864-08-16 00:00:00

Naval and Military Intelligence,

One of the most important subjects of inquiry
brought under the consideration of the Lords of the
Admiralty during their official visit to Plymouth
last week was that which relates to the dock ac-
commodation at Devonport and at Keyham. In
Devonport yard there are four , docks—viz., the
basin dock, 266 ft. long, now occupied by the Cale.
donia, 35; the new long dock (formerly two, one
inside the other), 415 ft. bin. long by 73ft. broad,
the longest at Plymouth, and which was occupied
in June by the Black Prince; No. 3 dock, 209 ft.
03. long ; and No. 4,263 ft. 4in. long. Nos. 3 and
4 are the docks which will probably be lengthened
to suit ships of modern construction. In Keyham
yard there are three docks,—No. 1, now occupied
by the Zealous, 277 ft. by 90ft. Bin., made just long
enough about five years since to receive the Hima-
laya with her rudder placed on one side ; No 2
dock, now oocupied by the Megmra, 281 ft. 9in. by
92ft.; and No. 3, or the Queen's dock, 94ft. broad
(the first ship received being her Majesty's ship
Queen), lately lengthened to 384 ft. When the
Channel squadron was at Plymouth in June No. 1
dock received the Edgar, No. 2 the Royal Oak, and
No, 3 the Warrior. By the report of the Select
Committee, published in The Sun on Friday, it ap-
pears that some of the witnesses think that two ad-
ditional first class docks are required here ; others
think three. The difficulty of deciding whether
there should be two or three bears no relation to
the difficulty of determining the length, breadth,
and position of the docks, so as, if possible, to anti-
cipate the size and requirements of the future navy
of Great Britain. The south basin, 7 acres, 32
perches, has during last year been deepened 6ft.;
it is now 25ft. deep, but it can be filled by pump-
ing to 28ft. The north basin, 5 acres, is being en-
larged in a northerly direction to, say, 10 acres.
The side of the northern boundary wall next the
basin will be finished with wrought stone, water-
tight ; the side to the north distant 60ft. is faced
with the rough stone from the buildings of the old
gunpowder magazine. There is some discussion
about the possibility of placing one dock inside the
other, as in some of the Russian arsenals, by which
mode the level of the platform of the inner dock is
considerably higher than that of the outer. Then
there is a difference of opinion as to whether the
docks should run north and south, parallel with the
Hamoaze, or at right angles with that harbour, like
those already constructed inside the basins both at
Devonport and Keyham. It is to be hoped that in
this case the longest dock will be placed immedi•
ately opposite the entrance from the sea, and not
like the Queen's dock in Keyham basin, the en-
trance to which is diagonal from the lock; and it is
further suggested that the entrance to the new
basin should, if possible, not be at right angles with
the stream outside. In order partly to remedy this
defect it has been recently necessary to erect a
diagonal jety outside thecomparativelynew entrance
to the south basin of Keyham Steamyard. From
what transpired during the visit of the Board to
Plymouth there appears to be no present intention
to build iron ships there. It is more probable that
Pembroke Dockyard, which is so near the iron and
coal districts, may be converted for that purpose,
and that at Keyham increased facilities will be
given to fit ships out after they are constructed—a
duty for which that yard appears, by the report of
the Select Committee, to be admirably adapted.
The screw steamship Majestic, 80, Capt. James
A. Paynter, from the Coastguard service at Liver-
pool, arrived in Plymouth Sound yesterday morning.
The official trial of the new steam tender, con-
structed on the double-screw principle, which has
been built for the iron frigate Achilles, took place
in Chatham harbour yesterday afternoon, under
the superintendence of the cfficials connected
with the dockyard. It was highly satisfactory,
and showed the immense advantages possessed by
vessels fitted with twin screws as compared with
those driven by the single propeller. The little
steamer tested yesterday is in all respects similar to
the tender recently constructed at Chatham for
the Bombay, 67, 400-horse power, Capt. Colin A.
Campbell, flagship of Rear-Admiral the Hon.
C. G. J. B. Elliott, C. 8., and fitted with engines
by Messrs. Penn and Co. She is exactly 42ft. in
length and lift. in breadth, or in other words, is of
the dimensions of an ordinary man-of-war's launch.
From a vessel of this kind she only differs in being
fitted with a portable steam engine for driving her
screws. Her machinery, which has been con.
strutted by Messrs. Maudslay, Sons, and Field, is
nominally of 3 horse power, but being on the high
pressure principle, and capable of being worked up
to 100 lb. to the square inch, her power can be in-
creased to that of 26 horses. Each screw is driven
by means of its own independent shafting, which
thus enables either propeller to be worked either
ahead or astern. The screws are four bladed and
are set at a pitch of 3ft. 4iin. The diameter of
each screw shaft is 2in., and the length 18ft. There
are four cylinders, each of 41b. in diameter, and the
length of the stroke is bin. The total weight of the
engines, with 9 cwt. 291 b. of water in the boilers, is
4 tons 7 cwt., or about one-third less than those of
the engines of the tender built for the Bombay. The
officials embarked at the dockyard pier yesterday,
the trial being under the direction of Mr. Baker,
chief engineer and inspector of machinery; Mr.
Warriner represented the firm of Messrs, Maudslay
and Co., and had charge of the engines. After
getting clear of the harbour the head of the steamer
was laid for Garrison Point and a run was made
down Gillingham Reach to the iron frigate Achilles.
At this time there was a pressure of steam of from
65 to 701 b., and the screws were making-300 revo.
'talons per minute. The trials with the tender then
commenced, and her rate of speed was ascertained,
but in consequence of the Lords of the Admiralty
not yet having had a measured mile laid off outside
Chatham harbour, an approximate estimate
only was formed of her speed, which was taken at
about 6,1 knots per hour, with 2SO to 330 revolutions
of the screw per minute. The most important por-
tion of the trials, however, was that relating to her
powers of steering by means of the screw without
the rudder. With both screws working ahead the
circle to port was made in 1 min, 15 secs., and that
to starboard in about the same time. Reversing the
screws—and in this lies the chief advantage of the
double-screw principle—the complete circles were
made in from 35 to 45 secs., the launch spinning
round in a circle the radius of which was about her
own length. This demonstrated the annoyance
which could be inflicted on a vessel of war of large
dimensions by a few of these launches, each armed
with a 40-pounder Arnistrong.
Yesterday the Royal Engineer.forces at Chatham
garrison were employed in extensive engineering
operations for the destruction of a large cliff, com-
posed of chalk, earth, and stones, at Caxton, near
Rochester. For about six weeks past a portion of
the Royal Engineers have been encamped in the
neighbourhood, and have been daily employed, under
the direction of Lieut. Fraser, in sinking the shafts,
driving the galleries, and in other operations re-
quired before the cliff could be destroyed. For this
purpose four shafts were sunk in various pelts of
the cliff, the depth of the lowest being 62 ft., while
the base of each communicated with galleries in
which were deposited the four charges of powder,
containing, in the aggregate, between 5,0001 b. and
6,0001 b. weight. The number of smaller charges
was 54, each consisting of 100 lb. of powder. The
necessary operations of" tamping," &c., having been
completed, arrangements were made for igniting the
charges, which was effected by means of a current
of electricity from tno voltaic battery, each charge
being fired simultaneously. The whole of the
operations were under the charge of Capt. Parsons,
while the general arrangementswere carried out
by Col. Lovell, C. 8., and Col. Scott. Everything
being completed, the bugle sounded the order to
" fire," and the batteries having been brought into
use the charges were ignited instantaneously. The
huge cliff then hulg eat with a dull roar, and the
entire mass was thrown down. The quantity of
chalk and flint detached by the explosion was cal-
culated at 1,000,000 cubic yards, but the exact
result will be ascertained to-day.
The following appointments were made yesterday
at the Admiralty :—George S. Goddard, assist.-
paymaster, to the Irresistible ; John C. Thompson,
firataclass assist.-engineer, and Thomas F. P. Shel-
ley, second-clays assist.,eugineer, to the U rt rge .