The Sun.
London, England, 1865-01-16 00:00:00

Naval and Military Intelligence.

During the terrific gale from the south-west
which prevailed early on Saturday morning, and
continued with more or less fury throughout the
day, her Majesty's large paddlewheel steamer Ter-
rible, 21, 800-horse power, fitting for sea in the
Medway, broke away from her moorings in the
river about an hour or two after daylighi, with the
tide about three-quarters ebb, and was driven on
shore close to the dockyard. Fortunately she took
the ground forward before she reached the granite
apron at the entrance to the steam basin, and be-
came embedded in mud and sand, with her stern in
comparatively deep water. Information of the
occurrence was immediately telegraphed to Chatham,
and the paddlewheel steamer Adder, Master-Com-
mander Blakey, and a party of riggers were de-
spatched to her assistance. In the meantime the
naval ;Commander-in-Chief, Vice-Admiral Sir C.
Talbot, Capt. the Hon. G. D. Deane, commanding
at the naval barracks, and other officials of the
dockyard, were on the spot, and with the assistance
of a large body of seamen, marines, and seamen-
riggers, wider the direction of Commander J. Jack-
son, Master-Attendant, the necessary :precautions
were taken to prevent the steamer heeling over at
dead low water, the Adder, Locust, and Sheerness
steamers standing by her to render any assistance
necessary. Towards noon the gale had sufficiently
moderated to allow of the requisite efforts being
made to float her, and by half-past one the steamers
had towed her off into deep water. Steam was im-
mediately got up on board, and she was removed to
the west shore, where she now lies. Until she has
been docked it will be impossible to ascertain the
extent of damage she has sustained, and, as she has
all her guns, most of her stores, and severalhundred
tons of coal on board, she will have to be consider-
ably lightened before she can go into dock. In
consequence of the enormous size of her paddle-
wheels it will be necessary to remove the outer ring
before she can enter the Sheerness basin. It is
uncertain, therefore, whether she will be docked at
Sheerness, or sent to Chatham or some other
yard. The Terrible is the second steamer which
was blown from her moorings during the gale
which has prevailed for some days. The
Tien-tsin, one of the Anglo-Chinese squadron,
parted from her anchor at her moorings in the Lap-
well, but was fortunately brought up again before
getting foul of any other vessel.
By direction of the Admiralty the officials con-
nected with the Steam Reserve are engaged in
making a careful survey of the various steamers
composing the Anglo-Chinese flotilla in the Med-
way, in order to enable them to arrive at the exact
value of each vessel, including all machinery and

stores.
The screw corvette Cadmus, 21, 400-horse power,
Capt. A. C. Gordon, sailed from the Nore for the
West Indies on Friday afternoon, calling in at
Plymouth to embark supernumeraries and for final
orders.

The propeller of the Achilles weighs about 1
tons. The blades or fans, which are twisted in the
usual way, weigh each 3 tons 3 cwt. ; the boss of
the propeller is 4ft. in diameter, the blades are 10ft.
3in. long ; the entire diameter of the propeller is
consequently 24ft. 6in. The whole is composed of
hard gun-metal, and was manufactured by Messrs.
John Penn and Son. It will be remembered that
during the late trial of speed at Portsmouth, two of
the blades of the screw were broken off, and it is
chiefly in consequence of this casualty that the
Achilles is now in dock at Keyham. She was
visited soon after her arrival at Plymouth, by Ad-
miral Robinson, Controller of the Navy, and last
week her machinery was inspected by Mr. Wright,
who belongs to the Engineering Department at
Whitehall, and by Mr. Knight, from the firm of
Messrs. Penn and Son. The two blades broken off
are next each other. In both cases the fracture is
close to the axis or boss ; in what was previously
considered the strongest part of the blade. The
blade here is about 2ft. 3in. wide, and is in its centre
at this part 9in. thick, diminishing or tapering to
the outer edges, and decreasing in thickness to the
end of the blade. The fractures do not appear to
have arisen through any defect in the castings,
but simply from the blades not being strong
enough to resist the enormous pressure, when
the engines, which are of 1,250-horse power
nominal, were worked up to a power estimated
at about 6,704 horses. Two new blades are
at Keyham, but it is very doubtful that with the ex-
perience obtained the Lords of the Admiralty will
permit the Achilles to go to sea provided with blades
similar to those previously in use. This doubt will
be resolved into a certainty when it becomes know-ns
that the two blades remaining on the boss are not
in working condition. The outer end of one is more
than 12in. out of its position, the inclination being
towards the ship. This defect was so much increased
when the screw was in full operation that the upper
part of the bladestruck repeatedly against the under
part of the ship's counter, and in order to step the
grinding it became necessary to reduce the revolu-
tions of the engines 32 per min. This blade has a
crack or fissure near its base exactly in the same po-
sition as the fractures in the broken blades, and it
astonishes everyone to think how the blade continued
attached to the boss. Under these disadvantages,
the Achilles made 9 or 10 knots an hour going from
Portsmouth to Plymouth, working only four of her
ten boilers. It now becomes necessary to note the
fact of the great flexibility of the blades of the screw
of the Achilles, notwithstanding their size and weight
and the hardness of the metal of which they are
composed. If our information is correct, the flexibi-
lity is greater than has ever before been found to
prevail in any screw propeller. It is partly owing to
this peculiarity that the blade last alluded to struck
against the ship's counter when she was put on high
speed. Engineers, in describing the action of the
screw in steamships, use the term " negative slip"
as that amount of speed which exists in excess of
the estimated speed attributableto the screw. When
the ship is going faster than the screw there is a
negative slip. The Achilles, under steam, has ex-
hibited an unusual amount of negative slip, which
is now attributed to the extraordinary flexibility
produced in the blades by the great power of her en-
gines. There is another point of interest connected
with the blades, and that is in their mode of being
fixed to the boss. On the boss, which is globular,
there arc four circular flats to receive the bases
of the blades. The flange of the blade is fastened
to the circular flat by 13 screws of about 21 inches
diameter each, and the flange in the case of one, if
not both, of the blades remaining, has been loosened,
notwithstanding the number and strength of the
screws. These screws are in two ranges, and it is
the outer screws which become loose. The fourth
blade is in consequence 2i inches- out of position.
This deficiency of holding power will form a subject
I:1r the grave consideration of the Government en-
eers, The propeller of the Achilles has sometimes
been described as Maugin's, which is patented, and
is much
used in the French navy. It is, however,
an Admiralty
'
four-bladed screw, the blades of which
are equal in size, and are .
a
eo)11 dist nt from each other.
The boss when take"
be uninjured—the apertureoff on
Saturday was found to
officers continue their full
and her engines. confidence is also perfect. The
condi-
tion of the ship in the
that the composition, a new one in.
It is to be regretted
the navy (Green's)
which was placed on hepr
of preventing
November last at
urpose
successful, patches
a cost of 9001. for the
corro-
sion has not been entirely
rust already exist, and water appeared to have ha
ga-
thered in some places under the paint. The season
of the year was unpropitious for drying the eora-
iso
sition, especially on the bottom of a ship in dock,
where ventilation is so much obstructed.
The iron screw steam troopship Megpera, 6, at
Devonport, is ordered to be put in commission.
She will probably hoist the pennant to-day.
The Dromedary, screw troopship, arrived at Spit.
head on Saturday from the coast of Africa, and sailed
thence again yesterday afternoon for Woolwich. She
sailed from Ascension on December 13, 1864 ; from
St. Helena on Dec. 24, and from Madeira on Jan. 4.
It is understood that the 9th depot battalion is to
be succeeded at Colchester by one of the battalions
of the 60th Rifles.
The 16th Lancers, at present stationed at Col-
chester, Ipswich, and Norwich, will shortly embark