IMPROVEMENTS IN PROTECTING 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 6th
August 1861.
I, EDWARD ALFRED COWPER, of Great George Street, Westminster, in the
County of Middlesex, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN PROTECTING 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
substances, 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

page_text: 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 con-
siderable extent from 90 degrees to the surface, the soft metal may act as a
lubricator 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 zinc or lead, or an alloy of zinc, 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 projectile 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
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
in two.

page_text: 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 flat. 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 fuze 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 hammered 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 immediately 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
salammonia, 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 screw 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 inay 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

page_text: purpose of introducing the plugs into their places. Other portions of my
improvements relate to the forming of such before mentioned or other armour
plates of malleable cast iron of great thickness, and the same may be coated
with soft metal, so as to form "lubricated armour plates," and they may be
connected together, as before described, so as to form "screw-locked armour
plates; or they may be simply fixed in their places by bolts, or any other
known means. I find that oxide of iron is a good material with which to
anneal and render malleable the cast-iron armour plates, the same being filled
in around them so that they shall be entirely surrounded by it when in a red-
hot state, and during the time of their being cooled down gradually. The
cast-iron armour plates may be surrounded with oxide of iron immediately
after they are cast, and whilst they are still red hot, the oxide-of iron having
been previously heated, or the cast-iron armour plates may be immersed in
oxide of iron, and submitted for a length of time to the action of a furnace,
so as to extract a large portion of the carbon of the cast iron, and thus render
it malleable. I find that soft red or other descriptions of iron ore or scales of
iron from forge hammers or rolling mills or other forms of oxide of iron
answer very well for the purpose of rendering cast iron malleable, as has-been-
commonly known and practised for many years, though other substances may
be used. I find that cast iron made from hematite iron ore generally answers
best for the purpose of being rendered malleable, as is well understood.