IMPROVED MECHANISM FOR DISCHARGING ORDNANCE
Year: 1871

page_text: PROVISIONAL SPECIFICATION left by Alexander Melville Clark at
the Office of the Commissioners of Patents, with his Petition,
on the 1st May 1871.-A communication from abroad by Henry
Arden, of Brooklyn, County of Kings, and State of New York,
United States of America.
I, ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, do hereby declare the nature of
the said Invention for "IMPROVED MECHANISM FOR DISCHARGING ORDNANCE,"
to be as follows:
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It is well known that the pitching and rolling of a ship at sea con-
tinually changes the angle of elevation of the guns, and that it is very
difficult under such circumstances to discharge the guns at the proper
moment.
The object of this Invention is to provide means for discharging the
guns whenever by the rolling or other motion of the vessel the gun
attains the proper angle of elevation, and for this purpose I employ a
medium, apparatus, or device, which is dependent upon the force of

page_text: gravity for its operation, and therefore performs automatically and at
the precise moment what has hitherto depended upon the varying judg-
ment and caprice of the gunner.
Such apparatus consists of a metallic ring pivoted on suitable supports,
within which ring is pivoted a metal bar, the pivots of the ring and of
the bar being equidistant. From this bar a metallic arc or sector is
hung, the centre of which arc or circle is the centre of the bar. Upon
the side of this arc, degrees, minutes, and seconds of the angle of
elevation are marked, the zero linc being a line which passes through
the centre of the base, and perpendicular thereto when the base is
horizontal. A pointer or index having a metallic point is attached
to the bar, which pointer may be adjusted to any degree, minute, or
second of elevation of the arc that may be desired. At the centre of the
base-another arc-is-fixed, which is in the same plane-as the bar before
mentioned, and at right angles to the base. This arc is electrically-
insulated-from the base and from the other parts of-the-machine, a wire
being attached to the said are running to one pole of a battery. Another
conducting wire is attached to any other part of the machine, and runs-
to the other pole of the battery. The point of the index is so adjusted
that in passing over the fixed arc it touches it, and by so touching
closes the circuit of the clectric current. In the circuit formed by these
conducting wires is an electric fuse for firing the gun, or an electric
magnet is arranged to pull a trigger and release a hammer to explode
a cap. A key is placed in the same circuit for opening and closing the
circuit, preferably arranged so as to close the circuit when the key
is pressed down.
The method of operation which I will describe is as follows:-The
distance of the object to be fired at being determined, and the required
angle of elevation of the gun being known, the pointer is adjusted to
and fastened at this angle, as marked on the pendent arc.
The gun
is then pointed at the object, its bore being parallel with the deck,
no attention being paid to its elevation or deflection in reference to the
horizon by the rolling or motion of the ship. When everything is ready
the key is pressed down, and so soon thereafter as the gun attains the
proper angle of elevation or deflection by the rolling or motion of
the vessel the point passes over the fixed arc, touches it, and closes the
circuit, and the electricity ignites the fuse or vitalizes the electro-magnet
(as the case may be), thereby firing the gun.
: ז־

page_text: It is evident that this apparatus can be used (if desired) for any
number of guns upon the same vessel, requiring the same angle of
elevation, and to be fired at the same object.
In lieu of clectricity I may employ the power of a spring or weight
to release the agent by which the fulminate is discharged, the said
power being brought into action by the force of gravity acting on a
pendulum as in the arrangement above described. Such an apparatus
will be found convenient in ship's boats where a battery would be found
inadmissable.
It is also applicable to guns used on land, particularly for field picces,
as it fixes the elevation accurately, no matter what the character of the
foundation. In this modification I employ a spiral spring may be com-
pressed by a bell-crank lever; one arm of which has a slot in its end
which catches on a pin in a second lever, the free end of which is bent
and rests on a flange of an arc, said arc being attached in a manner
capable of adjustment to a pendulum provided with a heavy weight. A
slit is cut in the flanged edge of the arc, through which the bent end of
the lever drops, when by motion of the ship the gun attains the previously
arranged angle of elevation. As the one lever falls the other slips off
the stud, and the spring retracts quickly and pulls down a hammer
on a percussion cap, or pulls a friction primer and fires the gun. A
retaining pawl is provided which is released by the gunner when he
wishes to fire his piece, and so soon after this is done as the proper
angle of elevation is attained the pendulum brings the slit in the arc
into position and releases the spring, thus causing the explosion.