The Sun.
London, England, 1864-09-22 00:00:00

Naval and Military Intelligence.

The Racoon, 20, screw corvette, Capt. Count
Gleichen, which arrived at Spithead from Scotland
on Tuesday, has gone into Portsmouth harbour, and
will be placed in dock to repair damage to her keel,

caused by grounding daring her recent northern
cruise. Soon after anchoring at Spithead on Tues-
day the wood and felt covering of her boilers was
found to be burning, but after some trouble the fire
was extinguished. An inquiry will be held on board
relative to the causeof the accident. Such fires are

of frequent occurrence on board her Majesty's ships.
but the evil has bFe❑ partially met by the Admi-

raity giving a permissive sanction to the use o

Spence's patent cement as a covering for boilers and

stem pipes, in lieu of the dangerous felt and wood
covering. To fully meet the question, however, and
prevent the recurrence of any such fires, the Admi.

ratty should issue a compulsory order on the sub

j,ct, and also alter their printed regulations relative
to the covering of new boilers, which specially
direct that all boilers and pipes shall be covered
with felt and wood. The Space cement is elastic,
Lion conducting and non-combustible, and has un-
dergone, with the most perfect success, a very
lengthened test of its efficiency on the boilers and
steampipes of the hydraulic engineihouse of Ports-
mouth Dockyard, where a 601 b. pressure of steam
is used.

The Pigmy, paddle steamer, Master-Commander
Vine, mailed from Portsmouth ou Tuesday for Vent-
nor, Isle of Wight, with the members of the com-
mittee on boat d appointed by the War-office and
the Admiralty to inspect and report upon the sys-
tems of day and night signalling for military and
naval purposes which has been lately worked out
by Capt. Frank Bolton, 12th Regiment, and Com-

wander Colomb, Itlyal Navy.
The Victoria, screw three-decker, fitted as the
future flagship foc the Admiral commanding her
Majesty's fleets in the Mediterranean, yesterday
made her steam reserve trial of speed at the mea-
sured mile in Stokes Bay, near Portsmouth. Six
runs were made over the mile with full boi!er power,
and gave the ship a mean speed of 11 800 knots.
Two runs with half boiler power gave her a mean
speed of 9.290 knots. The mean revolutions of the
engines were 58 at full power and 48 at half power.
With full power the half circle was made in 3 min.
20 sec., and completed to the full circle in 6 min. 43
sec. 'With half power the half circle was made in 4
min., and the full circle in 8 min. 20 sec. As the
Victoria's engines are 1,090-horse power nominal,
and as the ship drew but 23ft Tin forward and 25ft

9in aft, the speed attained at fail power cannot be
considered very great, nor is it probable the Victoria
will, when complete for sea with her crew and all
her stores on board, prove such a clipper in point of
speed as was at one time anticipated. Mr Warrener,
from the firm of Mandalay and Field, was on board
during the trial, representing the makers of the
engines. The machinery worked admirably, and is
without a doubt much too valuable for service in an
obsolete wooden three-decker. In turning at Spit -
head at the conclusion of one of her courses at the
measured mile, the Victoria came in collision with
the Italian bark Camillo, lying at anchor at Spit-
head, and bound from Newcastle to Palermo with a
cargo of coals. The Camillo lost her fore and main
topgallant masts and mizeu topmast. She was sub-
sequently towed into Portsmouth harbour by a Go-
vernment steamtug, and her damage will be re-
paired by the dockyard authorities.
The seamen and marines for her Majesty's iron-
clad frigate Achilles, 20, 1,250-horse power, Capt.
E. W. Vansittart, preparing for sea at Chatham,
are berthed on board the receiving ship Gloucester,
50, in Chatham harbour, until the Achilles is ready
to receive them. The detachments of Royal Marine
Artillery have joined from headquarters Ports•
mouth, and those from the Light Infantry companies
have been selected from the Woolwich battalion.
Tha Achilles is expected to bs ready to take
departure from Chatham in about a fortnight, when
she will proceed direct to Portsmouth,
The screw corvette Cadmus, 21, 400 horse power,
will be out of the ahipwrights' hands at Chatham
Dockyard in the course of next week, and will be
ready to b:: fl ) Oa out of dock during the approach-
ing spring tides. During the last few days she has
shipped her armament, which consists of 16 of the
cast-iron smooth-bore 8 inch guns, one 110-pounder,
and four 40-pounder naval Armstrongs, together
with the usualquantity of 12-pounder and 9-pounder
Armstrongs for field and boat service. According
to present orders received from the Admiralty, the
Cadmus is to be prepared for the first class steam
reserve, in readiness for immediate commission.
A number of workmen are now employed at
Chßtharn Dockyard, under the direction of Mr
Rivers, 'ho resident Admiralty civil engineer, in

of Science.

THE SUN, LONDON, THURSDAY EVENING, SEPTEMBER 22, 1864.

British Association for the Advancement

BATII, Tuesday.
The different sections resumed their sittings this morning,
SECTION G.—MECHANICAL SCIENCE.
This section was presided over by Mr H awkshaw, P.R. S.,
the president of the section.
Professor RANKINE, F.R.S., read a paper on some of the
strains of ships, of which the following is an abstract :—ln
previous scientific investigationsrespeeting the strains which
ships have to bear. it has been usual to suppose the ship
balanced on a point of rock, or supported at the ends on two
rocks, The strains which would thus be produced are far
more severe than that which would have to be borne by a
ship afloat. The author computes the most severe straining
action which can act on a ship afloat—viz., that which takes
place when she is supported amidships on a wave-crest, and
dry at the ends ; and he finds that the bending action cannot
exceed that due to the weight of the ship with a leverage of
1-20th of her length, and that the racking action cannot ex-
ceed about 16-100ths of her weight. Applying those results
to two very good examples of ships of 2,680 tons displace-
ment, ono of iron and the other of wool, described by Mr
John Vernon in a paper read to the Institution if Mecha-
nical Engineers in 1863, he finds the following values of the
greatest stress of different kinds created on the material of
the ship :—ln the iron ship, tension 3.98 tons per square
inch, thrust 2.35, racking stress 0-075. It follows that in
the iron ship thef actor of safety against bending is between
5 and 6, agreeing exactly with the best practice if engineers,
and that there a a great surplus of strength against
racking. In the wooden ship, tension 0'375 ton per square
inch, and thrust 0 293. Here the factor of safety is be-
tween 10 and 15, which is also agreeable to good practice in
carpentry. As fur the racking action, the iron diagonal
b aces required by Lloyd's rules would be sufficient to bear
one-third of it, only leaving the rest to be borne by the fric-
tion and adhesion at the beams of the planking.

A paper was read by Captain B. A. Henderson on the
practical progress of naval architecture in ocean and river
steamers, with suggestions for improvement in the steerage
of the Great Eastern and large and small ironclads, rams
and gunboats, similar to the Assam arsd Nautilus, by the
use of balanced rudders in bows and stern.
A paper was read by Captain Wheatly, E. N., on " Im-
provements in the Defence of Ships of War." He said—The
result of the experiments at Shoebury ness has publicly pro-
c' aimed that the 13-inch gun is the only gun to be thoroughly
depended on to act against iron plates. It must be, there-
fore, universally adopted as the chief naval gun. It may,
however, be modified by the introduction of gun cotton. As
yet we hear of no preparations for its adoption in our navy
but as we have mcunted up from the 8-inch to the 9-inch
and from the 9 to the 101, so I trust we shall shortly come
to the 13-inch. I will now proceed to submit a system cal-

culated to mitigate the great evil which would be caused by
fragments of iron and splinters of wood, as shown by the
experiments at Shoeburyness. A flag officer has suggested
returning to the old eysterm and taking off your hat to
the shot and letting it pass. But this does not meet the
emergency. It we entirely abandon plates we expose
ourselves to molten iron and other shells, in that case
much more destructive than solid shot. (The gallant officer
drew a diagram on the black board illustrating the system
he proposed to adopt.) The screen might not stop the solid
shot, but it would completely arrest all the fragments and
splinters driven in from the plates and backing forming the
under defence. I have placed the gun en barbate; in this
position it would be exposed to being dismounted ; by plac-
ing it in ports, the stop would be weakened to the depth of
the port. It is a choice between two evils. There is, how-
ever, a much greater evil than this which iron ships have to
contend with. In the only two naval actions that have
occurred lately at sea, both the defeated ships went down
the iron ship within an quarter of an hour after the fight
commenced. It appears to me that the best mode of attack-
ing an iron ship will be to imitate the practice of a breach-
ing battery on shore, where all the guns are directed on
the one spot where various lines meet. But as aiming and
hieting are nut quite the same, we must see if a ship can be
kept afloat after receiving shot below her water line. For
this purpose I propose, all the materials being ready before-
hand, screens of oiled south-wester canvass tied up between
the beams in the wings, and having a piece of heavy wire
rope at the bottom. When let down immediately the shot
has struck, a bag of wood shavings to be forced into the gap,
covered by a plank, and shored up from the inner side of
the wing. This will only stop the m .in rush of the water;
a great deal will still flow through the irregular crevices'
These I propose to stop by plastering the canvass to the
side w ith hydraulic cement, which is said to become fixed
under water in a quarter cf an hour. Where torn
by the jagged ends of iron, fresh canvas to be applied so as
to make a mould over them. I propose stopping other shot
holes in the surviving ship in the same way after the action
as neither planks nor iron plates will be of any use in
covering them. I submit, therefore, that this is an addi-
tional argument in favour of the system, and such is ad-
vocated in my former paper, in which—to assimilate it to
the practice on shore—the unplated gunboats, armed with
single 13-inch guns, resemble the line, and the much heavier
armed-plated ships the artillery. With respect to any diffi-
culties that may be started respecting the power of ships to
carry heavy guns, I have to observe that as long, I believe,
as two years ago, two 15-inch guns have been carried in
Federal vessels. That would be considered small in com-
parison st ith our scale. One prcbable resson why the Ame-
ricans have as yet no sea-going ironclads is that they are
directing all their energy and skill in constructing vessels
for coast and river warfare. The r monster guns show that
they are sufficiently capable of handling large masses of iron
to build sea-going ironclads when they rt quire them.
Admiral Sir E. 13EacatEn read a paper on "Improve-
ments in the Structure of Ships of 'War." Ile considered
that our ships of war needed no more protection than would
keep their hulls safely floating, with such protection for
those fighting the guns as might be deemed sufficient to
keep off shells and musketry, suffering heavy shot to pass
freely through ins,ead of causing spiral showers of splinters
such as resulted from the destruction of the late targets at
Shoeburyness. The present paper, therefore, dealt with a
mode of construction adequate for contending with ordinary
batteries, and also permitting external planking, and conse-
quently the old copper sheathing below water. It has been
so generally assumed that no thickness of armour plate could
be employed which would resist our new monster ordnance
that his attention had been directed to meet the difficulty
halfway, by protecting the mere vital shell of the lower
hull, so as defy the ordinary assault of any gun-bearing
vessel which should not by its accumulated weight or mass
of matter render defence impossible, It was important,
therefore, that such a tonnage should be provided as should,
as in the case of the Warrior class, be capable of floating
the contemplated armament independent of the forward aad
after compartments, which might be assumed, as mere as-
sistant means of flotation, and to be so fitted with cellular
divisions below the level of flotation as to render injury
to those parts below the reach of shot of very trifling
importance. In or er to satisfy the means of offence, cur
attention ought to be directed to the concentration of every
gun embarked on objects either ahead or astern. bearing in
mind that, under the throat that " no arm ,ur can withstand
near the line of axis of the
"
we must calculato on their em-
ploymentthe edcohtemaps
vessel. It was constantly asserted that the Warrior plates
contemplated
as uns,
possible
would stand no chance agains the monster guns of which
so much was predicted ; but the question was whether some
other mode could not be devised of applying the same weight
to greater advantage, or, assuming that it was penetrated,
could wo not avoid risk to the vitality of the ship by the
injury to be inflicted? He thought he saw his way to a re-
medy, which ho would explain. Now, assuming that an
iron spherical shot of 13 inches was the missile to be dreaded,
the question to be considered was not exactly what plate of
iron was to resist it—for the authorities stated that no rea-
sonable thickness, oven up to 12 inches, would withstand
the impact. Looking, however, only to the floating carcase
of the ship, and disregarding the ports until we had an im-
pregnable stage on which to place guns, then we should be
at liberty to increase the thickness to any amount. His pro-
position was to construct the ship on the customary plan of
close iron ribs, but filling up the interstices between the
iron with condensed teak. Now, assuming we constructed a
vessel with 36 inches depth of rib at the vulnerable portions
which shot could reach, which would probably involve 12
vertical feet of her side—say 8 feet below water and 4 feet
above—we should then have a vessel of stronger framework
than any now built, building, or in contemplation. Then,
assuming that these iron ribs presented 2 inches at the ex-
terior, tapering in 36 inches to ono inside, placed 6 inches
asunder, and filled in with compressed timber or other mat-
ter, we should have per cubic yard of bulwark 3,412•1251 b.,
that of the Warrior being 3,1e311)., showing only a differ-
ence of about 2901 b. to the cubic yard. It was yet to be de-
termined by actual experiment, whether that resistance
would offer the protection sought. Perhaps it would not,
but as he proposed to add a 6 inch-planking outside, he con-
sidered that the comparative danger with our present iron-
clads would be reduced to sill, or at least to something which
would satisfy the seaman. His plans for the final construc-
tion and fortification were not yet complete, but they would
probably be laid before the Government in March next. On
a previous occasion he had alluded to paper as an opposing
medium. In 1816 at Algiers a ream of foolscap, end on, re-
sisted a 68Ib shot from a 27 feet gun, at 76 yards ; and in 1854
he proposed to the Admiralty to construct moveable battery
rafts of brown paper, but the design was not carried out
Lately he learnt from a newspaper that, ten years after his
proposal, it was found that paper of 1-inch thickness was
fired at and not quite penetrated, while a similar shot went
quite through 10 inches of good oak, In conclusion, he
would observe that condensed rnillboard weighed less than
oak or teak, and, interposed in the manner he had sug-
gested, might form a target which would set even Big
Will at defiance.
The CIIAIRMAN said he had himself always felt consi•
derable difficulty in all the suggestions made from time to
time for building ships of war whero iron and wood were
used, on both of which the strength of the ship itself was
made to depend, It appeared to him, apart from the diffe-
rent modes of construction which had been suggested from
time to time, that what they ought to aim at and secure if
they could was to build a ship wholly of iron, so that the
ship, if stripped of all its other coating, would still be a
water-tight ship capable of navigating, and in this way
they would, of course, have a perfect structure. 'Without
that be did not see how they Were to escape the dry rot,