Improvements in Electric Primers and Breech Loading Guns.
Year: 1887

page_text: Date of Application, 7th Mar., 1887
Complete Left, 6th Dec., 1887
Complete Accepted, 6th Jan., 1888
PROVISIONAL SPECIFICATION.
Improvements in Electric Primers and
Breech Loading Guns.
Mechanism for Firing
1, CHARLES AMBROSE McEvoy of the London Ordnance Works, Bear Lane,
Southwark, in the County of Surrey, Engineer, do hereby declare the nature of this
invention to be as follows:-
The primer which is inserted into a small recess at the centre of the base of the
cartridge I form as usual of a small metallic case having within and insulated from it
a central metallic stem the rear end of which protrudes through a hole in the rear end
of the case so as to leave the end of the stem exposed and permit of a striker or contact
pin being brought into contact with it. Inside the case the inner end of the stem is
connected by a thin platinum wire with the outer case through which wire an electric
current passes when contact is made.
In fuses of this class insulate the central stem from the outer case of the primer
by means of cheap flexible material such as parchment leather paper or india rubber
which will readily bend instead of using hard material such as ebonite.
The primer by preference form of a short metallic cylinder of comparatively
small diameter with its edges at one end turned inwards. Into this end I place a flat
bottomed metallic cup having cylindrical sides which fit into the interior of the outer
cylinder.
A hole is formed through the centre of the flat bottom. One end of a metallic stem
contained within the cylinder and of smaller diameter than the hole is mado just to
protrude through this hole.
The end of the stem is also passed through the centre of a disc of parchment or
such like material of somewhat larger diameter than the cup. The stem has a disc
flange around it which is of a diameter to fit within the cup and rest against the
bottom being separated from it by the disc of parchment or such like material-the
edges of this disc of parchment also become bent up around the outer circumference of
the dise flange and separate it from the sides of the cup. These parts are also covered
with shellac which holds them together and further serves to insulate them.

page_text: The inner end of the central metallic stem and the outer circumference of the cup
have a thin platinum wire soldered to them.
Into the opposite end of the outer cylinder is inserted another metallic cup which
serves to enclose and retain within it gunpowder or other explosive. This cup has
also a central hole formed through its end through which the flash can pass when the
explosive is fired-over the hole is pasted paper or other material to retain the powder
and make a water-tight joint.
The striker or contact pin carried in the breech piece and which is brought into
contact with the end of the central stem of the primer when the piece is to be fired, I
arrange to be normally held back by a spring so that when the breech is closed no
contact is made until a press button at the rear end or side of the body of the gun is
pressed on. When the breech is closed the stem of this press button comes opposite
to and in a line with another stem in the breech block so that when pressed inwards
the stem in the breech block is pressed in also-when pressed in it moves end wise
(by inclines or otherwise) a rod at right angles to it and this at its opposite end forces
outwards the striker or contact maker and makes contact with the primer. An
electrical current then passes through the platinum wire of the primer and the primer
is ignited and the gun fired. This arrangement is especially applicable to guns with
sliding breech pieces such for example as the gun known as the Hotchkiss gun.
Dated this 7th day of March 1887.
CARPMAEL & Co.,
Agents for the Applicant.

page_text: COMPLETE SPECIFICATION.
Improvements in Electric Primers and Mechanism for Firing
Breech Loading Guns.
I, CHARLES AMBROSE M'Evoy, of the London Ordnance Works, Bear Lane,
Southwark, in the County of Surrey, Engineer, do hereby declare the nature of this
invention and in what manner the same is to be performed to be particularly described
and ascertained in and by the following statement:―
The primer which is inserted into a small recess at the centre of the base of the
cartridge I form as usual of a small metallic case having within and insulated from it
a central metallic stem the rear end of which protrudes through a hole in the rear end
of the case so as to leave the end of the stem exposed and permit of a striker or contact
pin being brought into contact with it. Inside the case the inner end of the stem is
connected by a thin platinum wire with the outer case, through which wire an electric
current passes when contact is made.
In fuses of this class insulate the central stem from the outer case of the primer
by means of cheap flexible material such as parchment, leather, paper or india rubber
which will readily bend-instead of using hard material such as ebonite.
The primer by preference form as shown in longitudinal section on an enlarged
scale at Figure 1 of the drawings hereunto annexed of a short metallic cylinder & of
comparatively small diameter with its edges at one end turned inwards. Into this
end I place a flat bottomed metallic cup B having cylindrical sides which fit into the
interior of the outer cylinder.
A hole is formed through the centre of the flat bottom. One end of a metallic
stem C contained within the cylinder and of smaller diameter than the hole is made
just to protrude through this hole.
The end of the stem is also passed through the centre of a disc D of parchment or
such like material of somewhat larger diameter than the cup. The stem has a disc
flange around it which is of a diameter to fit within the cup and rest against the
bottom--being separated from it by the disc D of parchment or such like material-
the edges of this disc of parchment also become bent up around the outer circum-
ference of the disc flange C₁ and separate it from the sides of the cup as shown.
These paris may also be covered with shellac which will hold them together and
further serves to insulate them.
The inner end of the central metallic stem C and the outer circumference of the
cup have a thin platinum wire E soldered to them.
Into the opposite end of the outer cylinder is inserted another metallic cup which
serves to enclose and retain within it gunpowder or other explosive G. This cup F
bas also a central hole F¹ formed through its end through which the flash can pass
when the explosive is fired-over the hole is pasted paper or other material to retain
the powder and make a water tight joint.
In place of the outer case A being so formed as simply to be pressed into a cavity

page_text: in the base of a cartridge it might be made with a screw thread around it for part of
its length and with a head at its rear end as in other fuses commonly made.
Other forms of electric fuzes than the one just described and shown in the drawing
and which are composed of an outer metallic case having within and insulated from it
a central metallic stem may similarly have the stem insulated from the outer case by
flexible material such as parchment or leather or paper or sheet india rubber or
gutta percha.
I will now describe the mechanism I employ for igniting the electric fuses.
In guns with sliding breech pieces such for example as the Hotchkiss gun I form
the breech piece with an insulated conductor in one or more pieces passing through it
from a point opposite to the centre of the rear end of the bore to a point opposite to
the end of a firing key carried by the rear end of the gun.
Preferably arrange for there to be a break in the electrical circuit when the breech
is closed not only between the end of the firing key and the end of the conductor
opposite to it but also between the other end of the conductor and the primer of the
cartridge and that both contacts shall be made when the firing key is pressed inwards―
or this second contact may be at an intermediate point in the length of the conductor
or may be dispensed with.
In the arrangement shown in Figure 2 of the drawing the two breaks are at
the two extremities of the insulated conductor which is carried through the
breech piece.
A is part of the barrel of a gun-B is a breech piece lying within a slot in its rear
end and closing the rear end of the barrel but which can be slidden or turned aside in
any ordinary way to open the breech. C is part of a metallic cartridge case carrying
at the centre of its base an electric fuze constructed as above described or of other
suitable construction.-D) is a contact pin carried by the breech piece and which is
brought into a line with the central line of the barrel when the breech is closed.
Normally its forward end is as shown held back by a coiled spring E so that when the
breech is closed no current can pass from it to the fuse-it can however be pressed
forward and made to make contact with the fuze by the action of sliding rods Fand G
and press button or firing pin H which is carried by the portion of the gun which is
in rear of the breech piece. The press button is shown as standing out from the rear
of this part of the gun but it might be at one side if preferred.
Normally the rods F, G and press button H are each held back by the action of a
coiled spring.
When the press button is pressed inwards it comes against the end of the rod G
and forces this rod inwards and its inner end acting on an incline on the rod F moves
this rod endwise and another incline upon it acting on the rear end of the firing pin D
presses the firing pin forward and brings its front end into contact with the primer in
the base of the cartridge.
An electrical current then passes from one pole of a small battery K through the
stem of the press button Hand through the rods F and G and contact pin D to the
central metallic stem of the primer or fuse and passes through the fuse to the outer
metallic casing of the cartridge and so to the metal forming the gun and from there
back to the other pole of the battery as shown.
The firing pin the rods F and G in the breech block and the stem of the press
button H in the rear of the gun are all held in guides of vulcanite or other insulating
material so that they do not come into electrical contact with the gun or its breech
block.
By arranging the firing mechanism so that no electrical contact is made with the
end of the central stem of the fuze until an electrical current is to be passed through
it and the fuse fired greater safety is obtained than when the only contact which
requires to be made to fire the fuse is that of the press button or trigger mechanism
used.
In place of employing sliding rods to transmit movement from the press button or
firing key to the pin Dother insulated mechanism for effecting the same object
micht ha orunlavad

page_text: In place also of the pin D being normally held back by a spring as described, it
might be pressed forwards by its spring so as at once to come into contact with the
cartridge primer when the breech of the gun is closed-the second break in the circuit
would then be between the rear end of the pin D and the rod For if two breaks in the
circuit are thought not to be requisite the pin D may be kept permanently in electrical
contact with the rod F either by a coiled spring between them or otherwise..
Having now particularly described and ascertained the nature of my said invention
and in what manner the same is to be performed I declare that what I claim is :-
1. In electric primers for central fire breech loading cartridges and which are
formed with an outer metallic casing having within and insulated from it a central
metallic stem which is made to protrude through the centre of the base of the outer
casing I claim insulating the central stem from the casing by paper, parchment or
such like sheet flexible material substantially as described.
2. An electrical primer constructed substantially as described and illustrated at
Figure 1 of the drawing.
3. In breech loading guns in which the breech is closed by a breech piece capable
of being slidden or turned aside at right angles to the bore forming the breech piece
with an insulated conductor carried through it one end terminating at the front of the
breech piece centrally with the bore of the gun and brought into contact with the
primer as the breech is closed and the other at the rear of the breech piece and
opposite to a contact pin which is carried within the portion of the gun which is in
rear of the breech piece substantially as described.
4. Constructing the insulated conductor which is carried through the breech piece
in such a manner that not only is there a break in the electrical firing circuit at the
press button or firing key but also in the length of the insulated conductor or between
it and the primer until the press button or firing key is moved to complete the
contacts substantially as described.
5. Arranging electrical firing mechanism of breech loading central fire guns in
such a manner that the contact pin carried by the breech block is not brought into
contact with the cartridge fuse simply by closing the breech but has to be moved into
contact therewith by the depressing inwards of a press button or such like trigger
mechanism when an electric current is to be passed through the fuze to fire the
cartridge.
6. The construction of the electric firing mechanism of breech loading guns
substantially in the manner herein before described and illustrated in the drawing
annexed.