The Sun.
London, England, 1868-01-10 00:00:00

THE SUN, LONDON, FRIDAY EVENII4O) jANITARY 10, 186 S,

was at the time the strongest piece carried habi-
tually by European or American ships, it is also
true that there are stronger guns in existence,
originally made in England and now in the
possession of foreign Powers. Our own 10-inch
gun is about as powerful at 1,500 yards as the 9-
inch is at 70 yards, and even the 15-inch American
gun can throw a shot with higher power than the
9-inch gun, though at considerable risk. The Rus-
sians have a 15-inch smoothbore, but its charge is
less than the service charge for the Rodman. True
economy would have been shown in providing for
the future as well as the present, and we cannot

acquit the Govcrnment of all blame in this matter.
Nevertheless, the danger has been much exagge-
rated. During the bombardment of Fort Sumter
eight Federal Monitors and one iron-plated ship of
16 guns were engaged for 2i hours with the fort.
Their guns comprised 15-inch and 11-inch smooth-
bored guns. The Confederate artillery had 10, 9,
and 8-inch smoothbores, 7-inch rifles, and smaller

pieces. About 80 rounds were fired from the ships ;
58 struck the fort, which was constructed

of brick in tiers of casemates, and which
could only reply with 33 guns in all ; yet in 45
minutes the ironsides had to retire ; in one hour
and 40 minutes the Keokuk, a two-turreted
Monitor, was sunk by a 7-inch rifled shot, and
the fleet was eventually forced to retire. The pro-
portion of missiles which struck the fort effectively
was about 4-10ths of the 58 which did not miss their

mark. The proportion of embrasures destroyed to
those exposed was 1-7th. Here was a case of real
warfare, in which the defenders had no iron shields
of any kind. However weak the Gibraltar shields
may be, they oppose a greater resistance to artillery
fire than any ship at present afloat, though they
will soon be surpassed by the Hercules and the

Wilhelm I.
We cannot calculate with accuracy what the pro-
bability of striking a target is when the guns are
fired on board ship during the ordinary manoeuvres
of an action. We have before referred to this point.

It is quite time that some experiments should be
made, an they might be at an almost nominal ex-
pense. We know what the guns can do on land, but
we cannot tell how great a loss of accuracy they
may sustain when fired from the moving platform
of a ship's deck. Neither have we sufficient in-
formation on the strength of iron defences. The
Iron Plate Committee was dissolved at the
very moment when their labours seemed about
to be crowned by many useful and practical results,
and we now suffer from that false step on the part
of the late Government by having to reopen the
question when our forts ought to be almost com-
pleted. There are many reasons for preferring
earthworks in some situations, but in others the ex-
pense of an earthwork would exceed that of an iron
battery, because the cost of the foundations would
be much gi eater from their increased dimensions,
and every spadeful of material would have to be
brought from a distance. Granite has been con-
demned by the results of every experiment that
has been made, and we have already far too many
of those whited sepulchres, the granite forts. The
Americans, like ourselves, have fallen iuto this
mistake, and they are now endeavouring to gain
more resistance by facing their many-tiered forts
with iron plates. By the time they have accom-
plished this their magnificent defences will have cost
enormous sums of money. The Iron Plate Com-
mittee declared that no front plates should be less
than Biu. in thickness, and since then the guns have
made vast strides in power of offence. Our opinion
is that the part of any structure which has to re-
ceive the first blow should be strong enough to take
the mischief out of the projectile. Behind the first
plates may come planks of iron or compound back-
ing on Chalmers's or Hughes's principle, and it is
probable that experiments will show the advantage
of an elastic backing behind all. If thick, solid
plates can be manufactured of such strength and at
such a price as to render them available, they may
be used, but in any case the stra,Aara should be
such as to leave a possibility of strengthening a
weak part indefinitely. Many of our shields are in-
tended fur granite casemates, and, as we have long
ago pointed out, the gunners are likely to be buried
under the ruins of the arches before the shields
can be penetrated. With these few preparatory
remarks we now proceed to sketch the results of
experiments hitherto made against the Gibraltar
shield retained in England to be tested.
The first trial proved the weakness of the bolts
and supports. Two chilled shot were fired from the
9.inch gun with a charge representing a range of
400 yards. Many bolt-heads ware torn off an d
thrown to the rear, and in one case the iron skin
was split,passed through the
shield. bh uetu
neithert considerably bent and
weakened. The heads of the bolts had been formed
by upsetting the iron bar instead of drawing them
struts
were projectile
drown from thicker material. They were not, there-
fore, strictly Palliser bolts.
The next experiment was not made upon the
shield itself, but is useful in considering the gene-
ral question, and, as it has not yet been fully
reported, we give it more in detail. Two
5-inch plates were riveted together back to back
with bolts of various forms. The front slab
measured sft. 6in. by sft. sin., the rear one 7ft.
by sft. 4in. They had Clot been planed, but were
put together in the rough, just as they had been
turned out of the rolling mill. They were held
together by four lines of bolts placed within 8i
inches of the sides and bottom, and 15 inches from
the top, thus forming a square. Five bolts held
the sides together, two were in the top row and two
at the bottom-14 in all. The bolts in the top and
bottom rows were 16 inches apart from centre to
centre, those at the side 131 inches. The seven
bolts on the right had screw heads, which screwed
into the front plate to a depth of about 5 inches.
Depth of thread about* inch ; pitch, five threads
to an inch. Six inches of shank 2/ inches diameter,
and 6 inches of the point screwed for a nut. The
back edges of the front plate were rounded off to
avoid shearing; the holes in the back plate were of
4 inches diameter, to take a wooden packing round
the bolt. The conical-headed bolts were of nearly
the same dimensions, but the head tapered from 4
down to 2/ ,inches, the diameter of the 6-inch
shank. Point screwed for nut 7 inches. These bolts
were made from 4-inch rolled bar iron drawn out
under the hammer, leaving the conical head. All
the bolts were nutted behind the rear plate with a
3-inch nut and 2-inch locking nut resting on a *-
inch iron washer. Three bolts on each side were
fitted with an additional wooden washer of 1 inch
elm between the iron washer and the plate. This
target, so composed, was supported against two
vertical iron bars 12 inches by 5 upon the face of
the hard-used 8-inch target. A chain, passing
round the upper part of the rear plate, served to
steady the structure. It must be understood that
the experimental target was only supported by its
veteran comrade in the sense that a shield is sup-
ported by the savage who uses it. The 9-in gun,
the exact powers of which are now so well known,
was brought face to face with its antagonist, and
three rounds were fired from it.
Round I.—Solid Palliser shot of 2501 b., charge
251 b., to represent a range of 1,600 yards. The
projectile struck with a velocity of 1,082 feet ; total
energy 2,029 foot tons, or 724 foot tons per inch of
shot's circumference. The blow took effect nearly
in the centre of the front plate, which it pierced.
The rear plate was indented and slightly cracked
behind. No effect upan the bolts appeared to have
taken place.
Round 2.—Same gun and projectile, charge 371 b.,
to represent a range of about 400 yards. The
shot struck low under the hole made by round 1,
penetrated the front plate, and showed its nose
through the back plate. Several cracks were de-
veloped in the front plate from the shot-hole
to the adjacent bolt-holes. One bolt at the bottom
left-hand corner (conical head, iron washer)„,"was
broken at the head. The next bolt had its head
drawn into the plate one inch, but held well.
One bolt with screwed head and iron washer was
broken off behind at the nut. The iron struts
were permanently deflected about half an inch.
Velocity on impact, 1,275 feet ; total energy,
2,818 foot tons, or 100.6 foot tons per inch of cir-
cumference.
Round 3.—This time a full servile charge of 431 b.
was used. The shot struck about 16 inches above

No. 1, and perforated both plates, digging its nose
about an inch into the Bin. target behind. Both the
upper corner bolts were broken, one being screwed,
the other conical-headed, both with iron washers.
The struts were deflected about three-quarters of
an inch. Various cracks in the front plate ran
from the hole.
This was not bad endurance for so small a tar-
get, and the gunners behind would have been pro-
tected from all danger at 400 yards. A plate with
a larger surface would yrobably have cracked less,
and four bolts only out of 14 were broken, none of
which had wooden washers.
A still later experiment was made with the Gib-
raltar shield on the 19th of December, when two
rounds were fire 1 at it from the 9in. gun with Pal-
liser shot and a charge of 371 b., representing by the
velocity given a range of 400 yards ; two Palliser
shells with a charge of 431 b., the fall charge of the
gun ; and.one American cast-iron shot, with 501 b.
of English powder (equal to 601 b. of American),
from the Rodman gun, the range in all cases being
70 yards. The effect was a general shaking and
disintegration of the parts of the target, which was,
however, fairly penetrated by only one of the various
projectiles—the first Palliser shell fired from the
rifled gun. With this one exception the gun be-
hind the shield would have remained undamaged
after having received in all seven rounds, and the
use of a rope mantlet protects the men quite suf-
ficiently from broken bolt-heads. The American
shot rebounded from the shield, but seriously
damaged the already weakened supports. The shell
which passed through struck near the point where
the longitudinal junction of the two front plates
crosses the vertical junction of two plates forming
the second layer—a rather weak spot. The second
shell, also fired with a full charge of 431 b., failed
to penetrate. Bulges there were in plenty, fis-
sures in the skin, and bending of supports ; but,
while the experiments have shown the necessity for
front plates of at least eight inches, the question of
backing to them cannot be considered as definitely
settled until other constructions have been tried
behind the same plate, or other shields at the
same price proved by experiment to be stronger.
We believe that the cost of each Gibraltar
shield was about £9BO, and though the pre-
sent examples have been shown to be deficient
in strength, there is no proof yet that the syStem
must be condemned. Weight does not form any
element of the question. The object must be to
obtain the greatest strength at the least cost.
Coming experiments at Shoeburyness, the prepara-
tions for-which we lately described, will bear upon
many important points ; but, after all engineering
questions have received full investigation, military
and financial reasons may prevent the adoption of
the best model, except in the most exposed posi-
tions. Above all things, let our artillerymen and
sailors bear in mind that more depends upon their
courage and upon the rapidity and accuracy of their
fire than upon the thickness of the walls with which
they will be surrounded. Tegethoff's wooden ships
dashed boldly into the thick of the battle, and not a
boat was lost. Albini was more-prudent, and the
result was the defeat of the Italian fleet with the
oss of two ironclads.—Tirnes.

THE PROGRESS OF TELEGRAPH' IN
THE YEAR 1867.

The events connected with the extension of tele-
graphic communication in 1866 were the most me-
morable ever recorded in history, for in that year
not only was a complete cable, uniting the Old
World and the New, successfully submerged, but
another, which was considered irretrievably lost by
the general public, was recovered from the depths
of the Atlantic. It might have been expected that
the marvellous success" achieved by thos3 who by
indomitable perseverance and scientific skill esta-
blished such valuable agencies of correspondence
between England and America would have prompted
others to initiate enterprises of a similar character
in other directions, but the commercial depres-
sion of last year acted detrimentally on the
advancement of telegraphy, as it did on almost
every speculative scheme. Still, some of the
facts connected with its history and progress
during the year . 1867 are peculiar and inte-

resting. The first prominent occurrence was the
repairing of the Atlantic cable of 1866, which had
broken some two miles from the Bay of Heart's
Content. It appears that when the shore end of
the cable referred to was being laid the Great
Eastern, from which it was paid out, was in
a fog, and it was laid in a shallower part of the
ocean than was originally intended by the engi-
neers. It was found that an iceberg, which had
grounded in 27 fathoms, was the cause of the acci-
dent, and the cable was repairel in the marvellously
short space of 48 hours, under the supervision of
Mr. Henry Clifford, C.E. The same rope broke
again in July about 87 miles from Newfoundland.
Thirteen miles of it were picked up by the ship.
Chilton, under the direction of Sir &timid Can-
ning, and laid in a deeper channel than that which
it had formerly been deposited. This was tho first
case of what may be called ordinary repair to the
Atlantic lines, as contradistinguished from pick-
ing up and splicing, and the promptitude
with which it was effected afforded another proof of
Sir Samuel Canning's ability and skill. It may be
here remarked that not the slightest interruption
has yet occurred in the cable of 1865. A cable has
been laid between Havannah and Key West, Florida,
and a second line between Key West and Punta
Rossa. The first is sheathed in iron and weighs
2.15 tons to the nautical mile. The route of it is
across strong and variable currents and over about
1,000 fathoms. A curious Miscalculation took place
while this line was being constructed. Owing to
the phenomenon of under currents the cable assumed
a direction over the stern as if the current was con-
tinuing to go west (as it actually did during the
first 20 miles) when it was really going east. The
result of this miscalculation was that the supply
of materials ran short, and the line had to be
completed with part of the Key West and Punta
Rossa wire, and the latter finished with a portion
of what was intended for a Red Sea cable. The
whole length of the section is 120 miles, and
on the Havannah coast the shore end runs into
450, and on the Key West into 136 fathoms.
The shallowness of the bed on which a great por-
tion of the Key West and Punta Rossa line lies ex-
poses the gutta percha covering to a severe test in
the tropics. Some of it is laid on mud banks, where
the normal temperature is between 80 deg. and 90
deg., and it has no other " serving" to preserve
it
from rust. We may here add that during the pro—
gress of the expeditions in which these lines were
established considerable loss of life took place among
the staff which superintended its construction. A.
line has been laid from Placentia to Lloyd's Cove,
Sydney, and touches at the French island of St.
Pierre. Unlike the Atlantic cable, this is sheathed
in iron wires and weighs 2.25 tons per nautical mile
generally, and 11 tons per nautical mile at the shore
end. The whole length of the section is 301 nau-
tical miles, and every indication has been given
that its general insulation is perfect. The
South Foreland and La Panne, in Belgium,
have been also united by a line of tele-
graph which contains four conductors, two of
them consisting of recovered portions of the Cromer
and Emden cable. The La. Panne line is 47 miles in
length, and the wire is covered with asphalte and
an outer " serving." In Persia a special loop line
from Khanakeen to Teheran and another from Te-
heran to Bushire have been erected. These are,
however, of no very great importance as alterna-
tive lines, for which they are intended, between
Bagdad and Bushire, for the line between Bagdad
and Bassorah is working well, and that between
Bassorah and Bushire has never been interrupted.
Considering, however, the Russian position, the
line between Teheran and Bushire is not without its
value. For the purposes of the Abyssinian expe-
dition Major Uharnpain, R.E., has taken out mate-
rials and a staff for the construction of a semi-per-
manent line from Anaesley Bay to the final head-
quarters. This will consist of copper wire, and the
insulators will be attached to bamboo supports.
For flying telegraphs forty miles of Hooper's wires,
without iron covering, have been supplied. This
peculiar species of wire resists the power of the
sun better, it is said, than any other, and by