IMPROVE- MENTS IN FORTIFICATION FOR THE DEFENCE OF SHIPS, BATTERIES, AND FORTS
Year: 1862

page_text: PROVISIONAL SPECIFICATION left by George Clark at the Office of the
Commissioners of Patents, with his Petition, on the 12th December
1862.
I, GEORGE CLARK, of No. 30, Craven Street, Strand, in the County of
Middlesex, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN FORTIFICATION FOR THE DEFENCE OF SHIPS, BATTERIES, AND FORTS," to
be as follows:-
This Invention comprises several parts which are herein described in
numerical order.
The first part is a system of defensive armour composed of a combination of
plates or sheets of iron or other metal with plates or sheets of tough material
of less specific gravity than iron, alternating with each other and closely com-
pressed and fastened together side by side, forming a compact body calculated
to resist the penetrating force of projectiles, by opposing to it either the edges
or flat surfaces of a mass of combined plates. The plates of metal should be of
such à degree of thickness as to possess a ready elasticity, for which purpose I
recommend that their thickness should not exceed 1 inch, varying from that
thickness to th of an inch. Metal plates exceeding 1 inch in thickness may
be used, but they will not be so serviceable in carrying out the principle of
regulated elasticity, as thinner plates, readiness of lateral spring combined with
lateral compression of the metal plates between plates of tough and hard but
somewhat yielding substances being the action on which I rely for the success
of this combination, and which will be more efficiently carried out by opposing

page_text: the edges horizontally, vertically, or at an angle rather than the flat surface of
the plates to the projectile force. The plates or sheets of tough material are
to be of about the same thickness as the metallic plates, but they may be
thinner or thicker, according as experience and circumstances may determine
which is best. The materials I intend to make use of for these plates are
vegetable fibre, such as hemp, flax, cotton, wool, hair, jute, cocoa-nut fibre, or
any other kind of textile plant or woody fibre. By teasing and crushing or by
maceration or mastication, with or without the aid of cold or hot water or of
steam, I reduce these materials to a broken, fibrous, or pulpy state, and in
some cases I mingle them with glutinous material, and then, with the aid of a
drying and heating process and compression between rollers or in a press I
form the fibrous pulp into sheets or plates of the required thickness, or I make
use of the manufactured articles known as cardboard, millboard, scale board, or
papier maché; I also intend to employ split cane, or india-rubber either in its
natural state or in the form known as vulcanized india-rubber, or vulcanite
and gutta percha, or leather, together or separately, for the formation
of the tough plates or sheets, the essential condition being the toughness of
the material. Wood cut into thin planks may be used in lieu of the before-
mentioned materials, but wood in its natural state will not answer the purpose
so well, because from its cellular structure it is defective in the required
toughness and would be easily crushed; therefore, when I use wood in planks
for the above described purpose, in order to give it toughness and preserve it
from decay, I intend to saturate it with a metallic solution, and with or without
saturation, to steam and compress the wood in the manner well understood.
For convenience in this description I call the plates interposed between the
metal plates, tough plates. With the iron and tough plates prepared as above
described, I form blocks of the proper or convenient size as armour plates for
covering ships or batteries, either by placing them against a backing one by
one in alternate layers of metal and tough plates and cementing or fastening
them together side by side as the work proceeds, or I form compound blocks
of the two kinds of plates. In preparing the materials for the tough plates I
intend to saturate or mingle them with substances which shall render them
incombustible and waterproof. For the purpose of fixing the two kinds of
plates to each other I intend to use marine glue or india-rubber cement, or
other strongly adhesive substance or preparation. In order to fasten the blocks
or plates which may be fixed vertically or horizontally to a ship or battery, I
intend to use two methods, namely, either my compound dovetail fastening
described in Her Majesty's Letters Patent, No. 482, granted to me and dated
the 25th February 1861, or the following method, which forms part of this

page_text: Invention:-The foundation or bearing surface to these blocks is to be either
the skin of an iron ship or an iron plate fixed for the purpose to the side of
the ship or battery. The foundation to the blocks may be wood or any other
material of which the ship or battery is constructed, but I consider it impor-
tant to interpose an iron plate between the structure and the armour. To the
foundation plate, in a vertical or longitudinal direction, according as the
armour blocks are to be fixed, I rivet or screw the flanges of external angle or
T-iron frames of the same depth as the depth or thickness of the armour
blocks, so that when these are in their places abutting against the foundation
plate, the edges or outer surfaces of both shall be exactly level with each other.
The external angle or T-iron frames may be made with flanges of such a
width as to meet each other and entirely cover the foundation plate, or without
a foundation plate to form the bearing surface to the armour blocks. The
external angle or T-iron frames referred to are to be parallel and distant apart
the exact width of the armour blocks for each strake or series, which I intend
shall be in two or more masses to form the width. Their length may be
varied according to the requirements of the structure to be armour plated.
The dimensions I prefer and recommend for the blocks are 6 or 7 feet by 2
or 3 feet, but it may in practice, be found convenient to increase or diminish
them. Between the masses of the blocks I interpose flat wedge plates slightly
tapered or dovetailed of metal only, or of layers of metal and tough plates. of
precisely the length and width of the plates composing the armour blocks.
These wedge plates are made with bolts welded or otherwise secured to their
inner edge, such bolts fitting into corresponding holes in the foundation or
backing plate, and passing through to the inside of the structure to which the
armour is to be fixed. The wedge plates being driven home will consolidate
the masses and plates of the armour and compress them tightly between two
external angle or T-iron frames fixed in the manner before described. The
points of the bolts are then screwed or rivetted, & the blocks are firmly held in
their places. This wedge plate fastening may be used alone or in combination
with my compound dovetail fastening before referred to, or any other kind of
fastening of the annexed Drawings, Figs. No. 1, 2, 3, which are not to scale,
illustrate the plan of the first part of my said Invention, which may also be
applied as backing to armour plates.
The second part of this Invention refers to through bolts, and is for the
purpose of counteracting the tendency of a conical bolt head when struck by a
projectile to act as a wedge and split the armour plate. I effect this object
by means of a tubular sheath with a conical bore placed under the bolt hole in
the armour plate, through which sheath the bolt passes and rests upon the

page_text: shoulder formed by the conical bore of the sheath, diminishing from the out-
side, the bolt being tapered to fit into the conical bore of the sheath. The
result is, that if the head of the bolt receives the blow, it (the bolt) is not
immediately driven into the armour plate, but is arrested or impeded by the
resistance of the tubular sheath and the bearing of the latter, of which the con-
struction is shown by the Drawing, Fig. 4. As a further prevention of the
splitting effect of the through bolt head, I propose to countersink it an inch or
more below the surface of the plate, and leave the orifice of bolt hole open
the depth of the countersink, believing this arrangement will not render the
plate any more susceptible to be cracked at the bolt hole, whilst it will
diminish the risk of the bolt head being reached by the impact of shot.
The third part of this Invention refers to iron knees of the form shown in
the Diagram, Fig. 5, or of any analagous form of construction. These knees
are to be placed 12 to 24 inches apart, in a vertical sense, between the frames
of a ship or battery, for the purpose of supporting the frames laterally and
strengthening them against fracture or collapse, as well as to afford additional
support to the armour and its backing between the frames. These knees may
be of any suitable dimensions to fit between the frames, and will vary according
to the distance the frames of the ship or battery and the knees themselves are
apart from each other.