The Sun.
London, England, 1864-03-02 00:00:00

Ironclad Ships.

At the Royal United Service Institution, on Mon-
day evening—Colonel Yorke in the chair—a paper
wan read by Captain J. H- Selwyn, R.N., " On
armoured or ironclad ships : their advantages and
defects." Captain Selwyn introduced the subject
with some disparaging remarks on the American
"monitors," which, he said, might perhaps be adapted

"or use on rivers, but were quite unfitted for the

general purposes of war ships at sea. He contended
that a properly constructed ship of war ought to
possess the following properties :—lt should bo fast
and manageable; it should be unsinkable; it should
be impenetrable by shot or shell ; and it should

be durable. The property of speed had, he said,
been attained in a great degree by most of the
ships recently constructed, but to attain that
advantage great length was required, which in-
creased the difficulty of ready management ; but
that difficulty he thought might be removed by the

adoption of double screws. - To render a ship as
unsinkable as possible, Captain Selwyn proposed
that the plan of partitioning by waterproof bulk-

heads and waterproof compartments should be
extended. lie would have the bottom of the ship
divided into compartments that would not hold
more than twenty tons of water, so that, supposing
a shot were to penetrate, or the ship were to strike
upon a rock, it would not sink. The defensive armour
of ships, as at present applied, would, he observed,
only protect them in still water, and in a
rough sea the unplated parts would be fre-

quently exposed to shot; ea that, without
some provision of the kind for rendering them
unsinkable, apparently invulnerable ships might be
soon sent to the bottom. With respect to armour
plating, Captain Selwyn regretted that, notwith-

standing the large sums spent in experiments, no
principles had yet bees established to determine the
best mode of resistance to the impact of shot. He
exhibited sections of all the British armour plated
ships, either completed or in the course of construc-
tion, and observed that none of them, with the ex-

ception of the Bellerophon, which has 6-inch iron
plates and 18 inches of wood backing, is impene-
trable by the guns now made. The importance of
the wood backing bad been greatly neglected in
some of the armoured ships recently constructed, for
recent experiments had shown its value in resisting
the passage of shot. Capt. Selwyn was of opinion
that, by using steel plates in constructing the skin
of the ship, great advantage would be gained, and
the additional buoyancy thus attained would enable
ships to carry thicker armour plating than is at
present possible. It had, indeed, been stated by
Mr. Bessemer that by that means ships might be

constructed that would be capable of carrying iron
plates nine inches thick. Captain Selwyn thought
that a much more satisfactory series of experiments
might be made to ascertain the resistance to impact,
and at much less expense, by means of a steam ham-
mer than by the mode now adopted, which led to no
definite results, and established no principles by
which the power of resistance to impact could be de-
termined. With respect to the d urability of iron ships
and of armour plating, Capt. Selwyn observed that
they are very liable to corrode by voltaic action, and
that in several instances the rivets are so corroded as
to drop out. It is very difficult to prevent such
voltaic action on a large mass of iron, for it takes
place not only when iron comes in contact with
copper or other metals, but different kinds of iron
when in contact will excite voltaic electricity, and
even different parts of the same iron bar will excite
it. Ho exhibited this by experiment with two

pieces of iron broken from the same bar, which
were immersed in diluted sulphuric acid, and on
being brought into contact electricity was excited,
as was shown by the deflection of a delicate galva-
nometer. No efficient means, he said, had yet been
devised to prevent this destructive action. He con-
sidered the most effective would be the application
of a thick coating of gas tar inside the plates.•

Admiral HALSTED noticed, in confirmation of
Captain Selwyn's observations respecting the ab-
sence of definite results from the experiments of
firing at targets, the different effects in the recent
experiments with steel shot at Portsmouth on the
same target, when fired at with the same gun under
apparently the same circumstances.
Mr. VICKARS, having understood Captain Selwyn
to recommend steel plates for the armour of ships,
mentioned a number of experiments which proved
that steel is not adapted for the purpose, for when
the plates exceeded three-quarters of an inch in
thickness they broke like glass.
Captain HARRISON mentioned the results of
several experiments at Shoeburyness, especially
with the 6001 b. shot, which at a distance of 1,000
yards smashed the Warrior target to pieces. The
gun, he said, carried the shot with the utmost pre-
cision. With respect to the use of steel shot, he
observed that the present object is to obtain the
best kind of shot at the least coats The Bessemer
steel as yet manufactured dces nut answer the
purpose, but from some experiments recently made
with an improved kind of cast iron, it is probable
that that material may be made to answer nearly as
well as the best steel which costs £5O per ton.
Admiral SARTORIUS expressed the opinion that it

was useless to attempt to resist shot of such enor-
mous size as those now fired, and that it would be
better to give them free passage, so that they might
do as little damage as possible.
Capt. FISFIBOURNE, 11. N , considered that undue
importance has been attached to iron•plating and
large guns. He objected to the plan adopted of
using small charges of powder, and he instanced
recent experiments made in France with a 30-
pounder gun, fired with charges of 29 pounds
of powder, the shot fired from which
penetrated a five inch iron plate at a distance
of 1,000 yards. He thought that by strength°
ening the 69-pounder gun, and firing it with an
increased charge of powder, an equal or better
degree of penetration might be attained as with the
guns of larger size fired with po tvder only one-
fourth the weight of the shot. The armour-plated
ships, armed with a few heavy guns that could not
be efficiently worked, would not be so effective in
action as if they carried a greater number of guns
of smaller size, fired with increased charges of
powder.

- Sir E. BELCHER said he knew several com-
manders of wooden ships now afloat who thought
that they were superior to the iron-clads, and who
would readily engage such a ship, feeling confident
that they would be able to give a good account of
her.
The meeting then adjourned.

The directors of the St. John d'El Rey Mining
Company (Limited, have received, by telegram from
Lisbon, the following report, dated Morro Velho,
Jan. 29:—Produce, eleven days of January, 12,701
oitavas ; yield, 6.138 oitavas per ton ; remittance,
80,509 ostavas. Working regularly—doing good
duty.

Messrs. Baring Brothers have received by this
mail 23,551 dollars on account of the Mexican divi-
dend fund. Messrs. Baring and Co.'s agents in
Venezuela advise that they have received for 55 per
cent. of the import duties from Puerto Cabello, for
three weeks, 10,459 Ms. 74e., and from La Gaara,
for two weeks, 8,093 dole. 25c. ; making a total of
21,252 dole. 99c. Messrs. Baring are now prepared
to receive for payment the coupons due on the Ist
January last on the Three per Cents. and One and
a Half per Cents. at the rate of 2 per cent. on the
former, and 1 per cent. on the latter. The coupons
are to be left two clear days for examination. The
same firm also announces that they have rcceivGd
£1,073 33 Gd by the present mail from the Custom-
house of Santa Marta for the New Granada divi-
dend fund.

LATEST INTELLIGENCE.

LREUTER'S TELEGRAMS.]

DENMARK.

COPENHAGEN, MAncil 1, 8.30 P.M.

Yesterday a squadron of Danish dragoons en-
countered two squadrons of the enemy's Hussars
between Vardo and Fredericia.
Our loss in the engagement amounted to nine
men wounded and missing, we captured one officer,
it surgeon, and 28 hussars,