The Sun.
London, England, 1867-12-26 00:00:00

IRON- PLATED CASEMATE.

To test various forms of protecting guns and men
a casemate has been erected at Shoeburyness, and
protected along its front with armour and backing
of different kinds. The piers supporting that part
of the arch immediately over the guns are 12ft
wide and Bft. deep, and are enveloped in iron-
plates i-inch thick, which are connected by angle
irons with the ironwork in front of the whole

structure.

The basis for the armour consists of a course of
2-inch plates laid completely over the surface of the
casemate, including the piers, and excepting only
the port. In all such casemates there is not only a
pier to be protected, but also a yawning space under
the arch, requisite for traversing the gun with its
carriage and platform. All this space except a
small port must be covered, and in the experimental
casemate at Shoeburyness a vertical row of caissons
formed of i-inch iron, and each containing a pillar of
concrete 15 inches thick, stands behind the 2-inch
plate where it is unsupported by the piers. The
caissons are riveted to angle irons and cross pieces
iu. thick. The port is 3 ft. wide and 3i ft. high
on the outside. A lateral range of 70 deg. is pos-
sible for the gun within the plate which forms the
exterior of the port ; the width of the latter is con-
tracted to 2ift. ; and, because this is the weak point
of the structure, there is fixed vertically on each
side of the port a solid forging of iron 9in. wide
and 13in. deep, immediately in rear of the armour
plate. These huge forged beams are strengthened '
and kept at their proper intervals by horizontal
iron Lars, Gin. wide and 7in. deep, halved into them
at the levels of the port sills. The forgings are Oft.
long. Their tops are bolted to a horizontal bar of
iron, bedded in the concrete backing, and more than
Gin. square in section. At the bottom they are se-
cured to a horizontal plate lft. wide and 3in. thick.
But, when the whole front is protected, all necessary
care has not been taken unless the interior is de-
fended against the bricks and blocks that will drop
from their beds on the defenders when the piers begin
to yield and the arches to tremble under successive
shocks, or against the bolt-heads flung backwards
as the strong plates quiver under the fierce strokes
of mighty shot. Again, therefore, iron is called in
to assist masonry. The arches over the men's heads
are lined with I-inch plates, and screens of the
same strength are disposed so as to guard the gun-
ners from splinters, whether of iron or masonry.
The iron-cased piers and arch are built of concrete
and brick in cement. The rest of the masonry is
of brick in cement. The brickwork of the arch is
18in. thick, and that portion of it which covers the
interval between the iron cased and the brick piers
is carried by wrought-iron girders. A course of
concrete lies above the brickwork, and is 15in. deep
at the crown of the arch. When we add that in
all cases permanent hollow bolt tubes pass through
backings and piers, so that the real armour bolts
can be taken out and the plates removed or ex-
changed without disturbing the rest of the struc-
ture, we shall have described the casemate which
has been built to carry the experimental armour,
and to test one or two novel plans. It will be re-
marked that the system of tubes for bolts affords
great facilities for building works preparatory to
plating them. This crowning addition can then be
made at any time, and of any strength that newly-
invented war engines may demand.
Upon the 2-inch plates covering the whole front
of the casement six different forms of armour are
bolted. Four of them, the first four that we shall
describe, contain a quantity of iron equal in all
cases to an 8-inch plate ; the fifth has an amount
equal to Bfin., and the sixth only 41in., concrete
being filled in between it and the 2-inch plate.
Commencing from the left as one faces the case-
mate, the first target consists of a vertical strip of
plating 4ft. 3in. wide and Bin. thick, bolted to the
2-inch plate and pier by bolts right through all.
Next to this is a strip of armour 4ft. 3in. wide and
4lin. thick, with hollow vertical iron stringers be-
tween it and the 2-inch plate. These stringers are
7in. deep, and of such section as to contain an
amount of iron equal to a 3iin. plate.
Next to this, and extending across, above, and
below the port, as far as its right edge, there is a
course of 6-inch plates with another kind of vertical
stringers (Mr. Hughes's) between it and the 2-inch
plate, still representing a thickness of Bin. of iron.
This armour is supported part.), by the left pier and
partly by the caissons containicg concrete.
On the right of the port the armour-plate, for a
width of 3ft. 4in., is 4in. thick , with vertica
stringers behind it of similar section to those in
No. 2 target, but rather heavier, to nab. ke up for the
diminution of half au inch in the thielmess of the
front plate.
Thence to the right of the casemate a