The Sun.
London, England, 1862-03-07 00:00:00

EXPERIMENTS AT SHOEB URY NESS,

Some interesting and important experiments were
made at Shoeburyness on Tuesday last, in the pre-
sence of the Lords of the Admiralty and a large
number of scientific officers and gentlemen, with a
view of testing the resistance offered by an iron target
built up to resemble a section of an iron frigate's
side, and specially designed by Mr. Fairbairn, sen.,
to show how the teak backing to the armour plates
might be dispensed with, and increased strength
obtained by a combination of ironwork alone. It
is necessary, in order to fully understand the ob-
ject and result of this experiment, to state that
when our first iron frigates were designed of the
Warrior class nearly all artillerists and scientific
men were agreed in the opinion that the armour
plates would require a wooden backing to deaden
and distribute over a larger surface the tremendous
concussion with which the shot would strike. It
was accordingly determined that the first frigates
should be plated with 41-inch armour, backed up
with a double layer of teak beams laid transversely,
in all 18 inches thick, and on this plan the Warrior,
Black Prince, kc., have been constructed. A tar-
get representing a section of the Warrior thus built
was fired at last October at Shoeburyness dur-
ing nearly two days, and, though every
description of solid shot from Armstrong
guns and 68-pounders were hurled at it singly
and in salvoes of six at a time, this method
of construction was shown to be practically invul-
nerable. No such satisfactory results in the way of
resisting the tremendous impact of the shot have
been obtained horn any other target tried at Shoe-
buryness before or since. But the Ironplate Com-
mittee had been led by many experiments, some
previous and some subsequent to that at the War-
rior target, to believe that greater advantages would
be gained by increasing the thickness of the armour
plates and reducing that of the teak backing. Ac-
cordingly in the three iron frigates now building
by the Thames Ironworks, Mr. Laird, and Mr. Mare,
it was decided to increase the thickness of the
armour plates from 41 to 61 inches, and to diminish
that of the teak from 18 to 9 inches. The Admi-
ralty, however, reserved to themselves the right of
still further altering the contract up to a certain
date, and having the plates of 61 inches without any
teak backing at all, in case there should be found
in the interim such a combination of ironwork as
would offer equal resistance, and thus do away with
the necessity of putting a destructible material like
wood between indestructible armour plates, which,
when once fixed, ought never to be removed. This
object was so desirable that many attempts have
been made to overcome the difficulties, which this
method of construction presented, the greatest of all
being that of fastening the plates to the target in
such a way as would enable the bolts to withstand
the tremendous jar the whole of the rigid and un-
yielding fabric receives when struck by a 200-
' pounder in full-flight. During last summer Mr.
Fairbairn, sen., constructed an entirely iron target
of small size ; but the experiments at this proved the
difficulties that would have to be overcome in securing

the plate, as with the jar caused by every shot the
bolts gave way, till most of the plates were brought
to the ground, and the target virtually destroyed.
On Tuesday another much larger target of Mr. Fair-
bairn's, constructed on a different plan, was again
tried, to determine whether the 18 inches of wood
between the armour and iron skin is necessary to
prevent the bolts and rivets being destroyed by the
vibration. This target, which was constructed by
Messrs. Fairbairn and Co., of Manchester, was 20
feet long by 10 feet high, with a porthole in the
centre. The two large plates going the length of
the target above and below the port were each 20
feet long, 3 feet 4 inches wide, and 41 inches thick.
The plates on each side of the narrow port were
only 9 feet long, but of the same width and thick-
ness. The two large upper and lower plates were
each secured by 15 2-inch bolts, fastened with
powerful screw nuts at the back, and the two
centre plates by eight bolts of a similar description.
These plates were fastened to 1-inch wrought-iron
plates, representing the skin of the ship, and be-
hind each line of bolts were straps of wrought iron
10 feet long by 9 inches wide and three-quarters of
an inch thick. The entire mass was supported by
ribs, representing the sides of a ship, 18 inches deep
and 18 inches apart, made of i-inch plates, secured
by angle irons 4 inches by 4 inches, and three-
quarters of an inch thick ; while the back of the
ribs was still further strengthened by four hori-
zontal strips of wrought-iron, 12 inches wide by
half an inch thick. the armour plates were not
wrought, but rolled by Messrs. Brown and Co., of
Sheffield, and the tonguing and grooving by which
the Warrior's plates are dovetailed together was
not resorted to in this instance, the plates being

planed flat at their edges, and entirely dependent
on the bolts for keeping their places. The whole
target was an admirable piece of workmanship, and
outwardly seemed strong enough to resist anything.
The experiment seemed to excite great interest,
and the principal iron manufactures and iron ship-
builders were present from all parts of the kingdom.
Among others were the Duke of Somerset, Lord
Mountcharles, Lord De Grey, Lord Clarence Paget,
Sir William Armstrong, Sir John Nay,: Admiral