IMPROVEMENTS IN PRO- TECTING SHIPS OF WAR AND LAND BATTERIES FROM THE EFFECTS OF PROJECTILES
Year: 1861

page_text: PROVISIONAL SPECIFICATION. left by Edward Alfred Cowper at the
Office of the Commissioners of Patents, with his Petition, on the 7th
June 1861.
I, EDWARD ALFRED COWPER, of Great George Street, Westminster, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN PRO-
TECTING SHIPS OF WAR AND LAND BATTERIES FROM THE EFFECTS OF PROJECTILES,"
to be as follows:-
Portions of my improvements relate to a means of causing shot and shell,
or other projectiles thrown by an enemy, to glance off from the surface of iron
or steel plates in a more certain and complete manner than is commonly the
case, by fixing a certain thickness of a softer metal on the face of such iron or
steel plates, which metal shall practically act as a lubricator to reduce the
friction or adhesion between the projectile and the plates at the moment of
impact. It is well known that for very light machinery that is subjected to.
only very slight strains the thinnest oil is best, whereas for very heavy machinery
that has to bear extreme pressure the best lubricant is tallow or other viscous
substance, so for the enormous force or extremely severe pressure. that takes
place when a heavy iron projectile strikes a thick iron plate. I use a much
tougher, harder, or more viscous substance, such as lead, zinc,. tin,. copper,
antimony, bismuth, or alloys of these metals, and which being softer than iron,
act as lubricators thereto. In the case of the use of the softer metals I unite
them to the iron, by preference, by soldering them thereto; thus the armour
plates may be simply galvanized with zinc, tinned, or leaded, so as to have a
coat of zinc, tin, or lead exposed on the outside, against which the projectiles
may first strike, so that when so striking at an angle differing to any consi-
derable extent from 90 degrees to the surface, the soft metal may act as a

page_text: Jubricator to reduce the amount of friction between the projectile and the
plate, and thus make it much more likely that the projectile will glance off or
slip on the surface of the plate instead of at once cutting or biting into the
surface and tearing it up. An extra thickness of zinc may be added to the
outside of the plate, or lead, tin, copper, antimony, or bismuth may be used;
but zine or lead, or an alloy of zine, tin, and lead, will generally be preferable,
both on the score of economy and on account of their not causing any increased
corrosion by galvanic action on any iron that may be exposed. In certain cases
I galvanize, tin, or lead the iron plates, and then before they are cold I place
thereon a sheet of soft metal properly cleaned, and when it has soldered itself to
the hot surface I cool the same with water or otherwise, so as to prevent the
sheet of metal from altogether melting; or in place of using a sheet of metal I
pour melted metal on to the hot surface of the iron plate, which must first have
been placed level to receive such melted metal, and have had an edge or guard
placed round the outside to keep the metal from running off the plate; but
this is not necessary in all cases, as lead, zinc, or tin, or some alloy of them,
may be poured on to the hot surface of the iron plate when it is at such a
temperature as to allow of the melted metal being moved about on the surface in
a semi-molten state, in the same manner as is commonly practised by a plumber
in making what is called a "wiped joint," and thus any required thickness of
soft metal may be put on. This plan of working is particularly applicable to
such plates as are curved or twisted, as for instance, the plates that occur all
round the curve of a ship, or at the head and stern thereof, or in curved work
in land batteries. I propose to call such plates "lubricated armour plates."
Other portions of my improvements relate to certain means of causing a
number of armour plates to assist each other in their resistance when a pro
jectile strikes any one of them, by so connecting the edges of the plates that
no plate can be forced in below its neighbours, until a large amount of metal
has first been destroyed altogether in its form, or sheared in two; this result
I attain without any "grooving and tongueing," or rabetting of the edges of
the plates, by boring holes of large diameter through the plates exactly in the
joints of the same when fixed in place, so that half the hole is in one plate
and half in the other, and in which holes I cut a strong coarse-threaded
female screw, and then screw into the same strong iron screw plugs, so as
entirely to fill the holes; thus it is impossible to move one plate past the other
without first shearing off or stripping the thread of the screw. Such screw
plugs I place at intervals all along the joints of the plates, and it is evident
that they are equally applicable to plates that are curved (as in the stem and
stern of a ship, or curved work in a land battery), as to those that are lat!

page_text: Where three or four plates join together, I prefer to put an iron screw plug
exactly in the joint of the plates, so that the extreme corner of each plate may
be supported, though the plugs may be put at a little distance from the corner,
if preferred. It is evident that the plates are by these means so thoroughly
locked together by the screws that very greatly increased longitudinal strength
is obtained in the direction of the length of the plates. I propose to call this
system "screw-locking armour plates." In some cases where it is required to
have a bolt at or near a screw plug passing into the frame of a ship, or into
the interior of a land battery to fasten the plate, I form the screw plug with a
long shank or bolt of smaller size on its inside end and screwed so as to
receive a nut, and thus secure the plate. The plates may be galvanized or
tinned or leaded, either before or after they are bored and screwed, and
the screw plugs may be galvanized, tinned or leaded, and when screwed
home in their places they may be heated to a sufficient extent to fuse
the zinc, tin, or lead so as to solder them in and thus thoroughly fix
them; or they may be prevented from unscrewing by having a portion
of the last thread of the screw driven down into a notch cut in the
plate to receive it; or there may be a small screw placed partly into the
side of the screw plug and partly into the plate, and having its end well ham-
mered down into a notch so as to prevent its moving, and this small screw will
effectually prevent the screw plug from turning, or a pin may be driven in
hard in the same situation, but into a hole having its bottom end slightly
larger than the top, by which means the pin will by hammering be caused to
swell at the bottom end, and effectually prevent its ever coming out. I prefer,
however, to prepare the plates with their lubricating soft metal surface imme-
diately after they have been forged and fitted to their places, and then as soon
as they are refixed bore the holes and screw them with a strong portable
drilling machine driven by a small portable engine or manual power, and when
the screw plugs are put in both they and the holes should be washed with a
solution of sal ammonia, by which means they will be caused to rust fast in
their places; the outside ends of the plugs should be prepared like the plates.
I prefer to form the screws plugs with very strong square threads, but the angle
of the sides of the threads may be varied in either direction somewhat, or
plain, square, or other shaped grooves may be cut in the holes in the plates
and in the plugs, but in such cases it is necessary to separate the plates for the
purpose of introducing the plugs into their places.