A VESSEL AND GUN, OR GUNS CONNECTED THEREWITH, FOR USE IN NAVAL WARFARE
Year: 1861

page_text: PROVISIONAL SPECIFICATION left by Charles William Siemens at the
Office of the Commissioners of Patents, with his Petition, on the
8th November 1861.
I, CHARLES WILLIAM SIEMENS, of 3, Great George Street, Westminster, in
the County of Middlesex, do hereby declare the nature of the said Invention
for "A VESSEL AND GUN, OR GUNS CONNECTED THEREWITH, FOR USE IN NAVAL
WARFARE," to be as follows:-
The object of this Invention is the construction of a weapon which is to
approach an enemy's ship or works of coast defence in perfect safety to within
a distance of from ten to twenty yards, and to discharge against it below the
surface of the water a bolt weighing from 15 to 20 cwt., with a velocity not
exceeding four hundred feet per second, which bolt or projectile is made to
explode after it has struck, so as to produce an irreparable breach in the side
of the vessel from three to six feet below the water line.
In the following description of this weapon I have assumed certain
dimensions and other data for calculations, which are introduced to de-
monstrate the feasibility of this Invention; but I wish it to be understood
that I in no way bind or limit myself to the dimensions and calculations
herein set forth, as they are only intended to serve as an example.
The weapon consists of a vessel 220 feet long, of very sharp lines, and
drawing only from 8 to 9 feet of water, carrying an engine of 500 nominal

page_text: horse-power, which will enable it to attain a speed of from 15 to 16 knots per
hour. This vessel is provided with a curved deck composed of armour plates,
of, say, 3 inches thickness, firmly bolted to strong cross bearers, and breaking
joint with each other, so as to constitute a continuous rigid structure. This
iron deck is covered with solid timber 6 ins. thick in the middle, and two feet
thick towards the sides, forming a regular deck, intended chiefly to weaken
the effect of the enemy's shot before striking the iron. Considering the
lowness of the deck, this vessel could only be struck at a very sharp angle, and
the shot would, it is supposed, glance of without breaking the iron plates.
The only projections upon the deck are three domes of 5-inch iron, which are
pierced all round, and serve the purpose of "hatchways" or "look-outs," and
for defence in case the enemy should come on deck. A large brass gun of 8
inches internal diameter, and 16 feet length, is fixed rigidly into the stem of
the vessel about four feet below the water line. This gun is made breach-
loading, being closed at the breach by means of wedges, and it can, moreover,
be closed at the muzzle, by means of a sliding valve worked from within the
vessel by means of a rack and pinion, or in any other suitable manner. It
may here, however, be observed, that in case this valve should be broken or
otherwise disabled, the gun may be loaded nevertheless by introducing a wad
in the part of the gun behind the wedge, and by pushing the same forward at
the instant when the breach-loading wedges are removed. This wad is then
followed up by the projectile and the charge, and the gun closed ready for
firing.
The projectile consists of a cast-iron cylinder containing two cavities, which
communicate by means of a fuse hole. The front cavity being filled with
gunpowder is closed in front by means of a steel head, which is tapered towards
the front, and is terminated by a concave surface, producing a circular cutting
edge to lay hold of the side of the enemy's ship in striking the same obliquely.
The second cavity receives the charge after the projectile has been placed in
the gun. Considering the great weight of the projectile (15 cwt.), and the
comparatively low velocity it is intended to attain (400 feet per second), it is
necessary that the charge should burn about three times slower than an
ordinary charge of gunpowder, in order to produce the same pressure within
the gun at every point. In order to insure this result, the powder is com-
pressed into a metal casing or cartridge forming three conical cavities in the
same, whence the combustion will proceed. The rate of combustion will thus
be limited, but will increase with the circumference of the cavities, so as to
maintain a somewhat uniform pressure behind the projectile during the time

page_text: of its accelerating flight. If we suppose the pressure of the powder gas to be
the same in this as it would be in an ordinary gun with a projectile of 180 lbs.
weight, it follows that the amount of force stored in this heavy projectile will
be at least three times greater, because its acceleration is three times slower,
and the accelerating pressure is allowed to act upon it three times longer.
This
gun is intended to be fired by the commander of the vessel by means
of a galvanic battery and connecting wires. When the charge of compressed
powder in the aftermost chamber is consumed in discharging the gun, the fuse
at the end of it will convey the fire to the formost close chamber, which being
filled with powder will explode, say, half a minute after the projectile has left
the gun, and cause an irreparable rent in the side of an enemy's vessel in case
it has not passed through the same, so as to leave two clear openings for the
water to rush in. Immediately after the discharge of the gun the slide at its
mouth is closed, the breach cleared, and the water contained in the gun having
made its escape into the vessel another projectile is introduced by the aid of a
travelling crane. The charge of powder is next introduced, the wedge re-
placed, the touch-hole fuse adjusted, and the slide at the mouth of the gun
withdrawn in order to make ready for a second firing. These operations need
not occupy more than five minutes. In order to prevent the water from
penetrating to the powder, the projectile is provided with one or two grooves
for the introduction of leather rings or other packing.
The engine for propelling the vessel should combine lightness and power in
the highest degree. If a steam engine be used, it should be furnished with
high-pressure tubular boilers and surface condensation. The conditions of
lightness and strength would, however, be more fully realised by the application
of a caloric or gas engine, such as those for which Letters Patent were granted
to me, and bearing date the 28th of August 1860, No. 2074. The absence of
boilers, together with a chimney (with its attendant smoke), and the com-
paratively small store of fuel that would be required, render the application of
such engines particularly desirable in the present instance. An arrangement
is provided for reversing the motion of the engine by the reaction produced in
discharging the gun. In order to prove the power and efficiency of this
weapon, it is necessary first to calculate the retardation of the projectile in
passing through the water, its penetrating force in striking, and the amount of
reaction that will be experienced in the vessel. Assuming the weight of the
projectile to be 1,500 lb., the velocity with which it leaves the mouth of
the gun 400 feet per second, the distance from the enemy's ship 60 feet, the
weight of the vessel 1,000 tons; we shall find that the force residing in the

page_text: projectile on leaving the gun is 1000 × 400-3,750,000 foot, pounds, or units of
force. The resistance in the water of a cylindrical body of one square foot
area, and moving with a velocity of 17 feet per second, is known to be about
50 lb. The resistance offered to the motion of the projectile in question would
be accordingly (its area being square foot)=x50x=9,204 lbs.
Neglecting the decrease of resistance which would take place in consequence
of a decreased velocity, but assuming 9,204 lbs. resistance to act during the
whole flight of 60 feet; the store of force communicated to the projectile will
be diminished to the extent of 9,204 x 60=552,240 ft. Ibs., and the projectile
will strike with a force of 3,750,000-552,240=3,197,760 ft. lbs., or with
an actual velocity of 370 feet per second. The crushing effect of the blow
will equal that of an Armstrong or Whitworth bolt of 142 lbs., striking the
object with a velocity of 1,200 feet; it may therefore be fairly assumed that
no vessel afloat would resist the same. The armour-plated vessels would have
no advantage over ordinary men-of-war, because their strong plating does not
extend beyond two feet below the water line, whereas the proposed projectile
would strike several feet below that line. The amount of reaction that will be
produced upon the vessel by the firing of the gun must be-
3,750,000 (force developed).
2,200,000 (weight of ship)
X29 10.4 ft.
that is to say, the velocity of the vessel will be checked to the amount of 10.4
feet per second, or the shock experienced on board will be equal to that of a
railway train moving at the rate of 7 miles per hour being brought to a sudden
stop. This amount of reaction will not, it is presumed, affect either the
structure of the vessel and engines nor the crew on board injuriously. The
case is certainly very different from a regular steam ram striking an enemy's
ship with a velocity of 15 knots per hour, or 25 feet per second, where the
effect of the shock will be greater in the proportion of 25: 10-426: 1.
This weapon might be used, firstly, in attacking an enemy's fleet lying at
anchor; its lowness of deck and absence of rigging would favour its approach
to within 10 or 20 yards of the first ship, which would be fired into, causing it to
sink or to be disabled if the blow were aimed at the rudder or propeller. The
attack may therefore be directed against a second vessel, and so on in rapid
succession. It might be desirable to fit the ram employed for such a service
with two guns, one above the other, imbedded in the stern in order to increase
the rate of firing, and to be able to fall back upon the second gun if one should
be disabled. Secondly, in meeting an enemy's vessel at sea, which, on perceiving

page_text: its danger, should seek safety in flight; the great swiftness of the ram will
enable it to overtake the same, and having approached to within a distance of
20 or even 40 yards, its projectile could not fail to hit, provided only that the
commander fires at the moment when the enemy's vessel covers the stem of
his vessel. Thirdly, in meeting a hostile man-of-war at sea, the ram ship
would give it some 100 yards berth, and on approaching suddenly wear round,
stopping the engines until its stem points directly towards the enemy, at a
moderate distance from the same, when the discharge should take place.
Fourthly, this weapon might probably be used with great effect in destroying
the enemy's land works, such as dock entrances and breakwaters.