The Sun.
London, England, 1864-01-28 00:00:00

THE NAVY.

VALETTA, Jan. 22.—The Trafalgar, 72, Capt. T. Mason,
has been detained here till the arrival of the Meeanee, 60,
Capt. G. Wodehouse, expected in a few days from Athens.
The Trafalgar will then proceed to England to be paid off.
The Cossack, 20, Capt. W. R. Rolland, received orders yes-
terday to hold herself in readiness to sail for Tripoli and
Benghazi. She is to convey Mr. Saunders, electrician to
Messrs. Glass, Elliot, and Co., to these places, for the pur-
pose of examining into the state of the Malta and Alexan.
dria telegraph cable, which has stopped working since the
13th inst. Mr. Saunders is expected from Marseilles to-
night. A steamer especially fitted for such employment
has been ordered from England to the Mediterranean to re-
pair the cable. The weather, which has been very boister-
ous for some time past, is rather calmer, but is not quite
settled yet. From Alexandria accounts have been received
that an English steamer, named the Atlas, employed in im-
porting horses and cattle for the Viceroy from France, had
gone ashore at Rossetta, but had been got off and safely
towed into Alexandria by her Majesty's ship Psyche, to
whose commander, Lieut. P. Sterne, great credit is due for
his exertions in the matter, This is not the ship of the same
name belonging to Messrs. Burns and M'lver, of Liverpool.
The Phcebe, 35, Capf. T. D. A, Fertescue, having completed
the repair of her engines in her Majesty's dockyard at this
island, will leave some time next week for the coast of Syria
to relieve the Liffey, 35, Capt. George Parker. The Eng-
lish ecrew steamer Semaphore, Capt. R. Green, arrived yes-
terday, from London 14 days, and Gibraltar six, with tele-
graph cable on board for Brindisi, and passengers Mr. G.
Henley and 15 labourers.
The iron-clad screw steamship Royal Oak, 35, Capt. F.
N. A. Campbell, having embarked supernumeraries for the
Channel Squadron and Royal Marines for the flagship
Edgar, now in the Tagus, is under orders to leave Plymouth
Sound for Lisbon, Gibraltar, and Malta. It will be recol-
lected that when docked in Keyham steamyard very serious
effects had been produced by the galvanic action of her
copper sheathing on the adjoining iron plates. Immediately
afterwards it was determined to protect an intermediate
space all round by the application of Hall's vitreous sheath-
ing; but it was subsequently resolved to use the vitreous
sheathing on one side and a band of zinc on the other. The
upper sheet of Muntz's metal, 14in deep, was therefore
stripped from the port side and a listing 7in wide and 31in
deep was cut into the ship. All the ends of the metal bolts
were then cut off. A plank 2in thick was introduced into the
bed of the cutting to prevent the ends of the bolts from
coming into eirect contact with the band of zinc, which was
lifia thick. It being fastened on the plank the space made
by the cutting became flush with the metal below and the
iron plates above. It is expected that this band will prove
a sufficient non-conductor to prevent the sheathing metal
from producing any galvanic action on the iron plates.
On the starboard aide about 3,500 of Hall's vitrified plates
have been glued or fastened en in a depth varying from 6ft
under the stern to 2ft at the bow. There is a space. more or
less, of 2in between the upper edge of the copper sheathing
and the lower edge of the iron plates; this space is lett in
order to cut off all connexion between the two metals, and
was well paid with Hall's anti-fouling composition. The
three lower tiers of vitreous plates are fastened on the wood
with composition nails ; those above are glued. The edges
of the upper tier are covered by the teak-rubbing pieces.
Some difficulty was experienced in fixing the plates under
the quarters and near the sternport, in consequence of the
shape of the ship. The thinnest plates were selected for
this purpose. Like the rest, they were forced on by hand
pressure only. Where galvanie action hs,d eaten through
the face of the armour plates, the holes or pits have been
filled with a mixture of Portland cement and Hall's glue.
It was, however, previously necessary to expose these pits
to the lengthened heat of burning charcoal, in order to ex-
tract from the iron the salt left by the previous admission
of sea water when she was in active service, To protect the
stem a plate of vitrified iron was prepared, 4ft 4in long, 13in
deep, 191-in wide, and iin in thickness. This plate was
brought home to the stem by vitrified screws (having en-
amelled heads) to within the 16th of an inch, it was then
puddled below, and hot glue having been poured in above,
the screws were driven in, and the plate was firmly fastened.
It is understood that zinc is more liable to be injured by
contiguity with Muntz's metal than iron, but the zinc band
can be readily replaced in dock without damaging the ship.
The Royal Oak will be accompanied by the gunboat Trin-
culo, tender to the Edgar.

Her Majesty's iron steam store ship Industry, Master
Commander Youel, from Rio de Janeiro, having landed
her victualling stores at Deptford yesterday, went down
to Woolwich to be docked and cleaned down, as her sides
are clogged with barnacles and seaweed.

Some testing of armour plates took place at Portsmouth
yesterday, which was attended with unusual interest from
the comparative results obtained with different kinds of
projectiles fired from the 95cwe 68-pounder cast iron gun
and the 100-pounder Elswick smooth-bore. Ihe plates
were each of 51in in thickness, 15ft 6in in length, and 3ft
3in in width. One from Messrs. John Brown and Co., of
Sheffield, was for the iron frigate Agincourt, and the
other was sent in by the Millwall Ironworks for the iron
frigate Northumberland. Both were tested in the first
place with cast iron shot from the 68-pounder gun in the
ordinary way, in order to award them their figure of
merit, according to the Admiralty regulations, for quality
of metal and manufacture. Both passed through this
ordeal satisfactorily, although tried severely by clusters of
shot impacts and edge blows. The maximum depth of
the indents was 2in, and the minimum 1 1-16 in. On
Brown and Co.'s plate, in its upper right centre, four shots
struck in a semicircular line, that measured but 32in
through the greatest extent of the curve. Throughout
this space there was only one small surface crack. On
, the left lower corner of this plate five shots struck imping-
ing on each circumference. Two of them were only half on
the plate's edge. There was nothing like penetration even
here—nothing, indeed, but a longitudinal opening of the
metal, about an inch in depth, and a slight stretching open
of the lamina) on the edge. The plate exhibited wonderful
tenacity and solidity, without the slightest appearance of
brittleness. The Millwall plate was also struck in several
places on its right edge, but without penetration being
effected, although a small semicircular piece, 24in in length
by 10in in width, was broken out through half the plate's
thickness. The lamina) were opened on the plate's edge in
the vicinity of the places struck. The plates were of un-
doubted excellence both in the quality of the metal and in
their manufacture. It is doubtful, indeed, if a plate supe-
rior in any wayto Messrs. Brown's was ever tested at Ports-
mouth. It is necessary to dwell thus on the extraordinary
qualities of these two plates in order to render clear the
true value of the firing which followed on the official testing
of the plates being concluded, and which was as follows :
Messrs. Brown's plate was selected for firing against with
improved cast-iron spherical (crucible) shot from the Els.
wick 100-pounder smooth bore gun (diameter of bore 9in
and weight 120 cwt 2qrs), with a charge of 251 b of powder.
Three shots were fired. No. 1 struck the plate on the lower
edge and touched a bolt. It produced an indent of 4in at
its greatest depth, with a diameter of 91in, and with only a
surface crack round the indent. No. 2 struck just over the
lower edge, producing an indent of 10in in diameter and a
greatest depth of 3 8-10 in, with a slight surface crack in the
indent. Both these shots were destroyed in the ordinary
manner of cast-iron projectiles. No. 3 shot struck fairly on
the plate, and part of it remained fastened in the plate's
outer surface. It will be seen that the damage ie.-
flicted by these improved cast-iron shot was hardly
commensurate with their increased weight and
the extra 91b of powder charge as compared with
the 68-pounder gun. The Millwall plate had next three steel
shots sent against it from the same Elswick gun, with a
similar charge of 251 b. of powder, and the results obtained
with these steel projectiles were certainly astonishing. Plates
have been pierced before by steel shot, but never one of
equal excellence with the Millwall plate of yesterday. No. 1
shot struck about 4in below the upper edge of the plate, a
distance away from any damaged part, and, breaking right
through, buried itself and the broken parts of the plate in