Year: 1887

page_text: Date of Application, 18th Feb., 1887
Complete Left, 10th Nov., 1887
Complete Accepted, 17th Feb., 1888
I, GEORGE STUART of the Elswick Works Newcastle-on-Tyne, Engineer, do hereby
declare the nature of this invention to be as follows:-
This invention has for its object improvements in electrical primers.
The primers are intended for use with axial vented guns more especially rapid fire
guns. They are of simple construction and possess the great advantage of being
easily renewed by being recharged and fitted with a new platinum wire and cap.
The primer is formed of a cylindrical metallic body by preference screwed on its
exterior to screw into the base of a cartridge case. At its rear end it is formed with
an enlarged head and its front end which is reduced in diameter has a screw cut
around its exterior for a copper cap to be screwed onto.
A cavity is formed centrally in the body from its front end nearly to its rear end.
From the rear end of the cavity is a passage of smaller diameter to the rear end of
the body. At the extreme rear end of this passage is also a shallow cavity of larger
diameter to receive a disc of ebonite or other non conducting material.
Inside of the main cavity formed in the body are placed discs of asbestos each
having a hole through its centre. A metallic spindle is passed centrally into the
cavity and through the holes in the asbestos discs and also made to extend through
the small passage at the rear end of the cavity. The spindle has a flange around it
to bear upon the discs of asbestos. More discs of asbestos are then inserted and
afterwards a metallic ring of gas check form. The ring and asbestos are then
subjected to a greater pressure than that produced in the gun. This forces the asbestos
into the small passage at the rear end of the cavity and forms it into a solid insulating
block. The ebonite insulator is then placed on to the rear end of the metallic spindle
the metallic spindle passing through it and also through a metallic disc which is
embedded in its rear end-and finally the end of the spindle is rivetted over.
front end of the metallic spindle has soldered to it a platinum wire which is also
soldered to a pin which projects from the front end of the body. The wire is then
surrounded with gun-cotton after which the cavity is filled with gunpowder and when
The

page_text: the copper cap charged with gun cotton is screwed on to the front of the body the
primer is complete and ready for use.
On an electrical contact being made by means of an insulated rod passing through
the axial vent of a gun the electricity passes through the central spindle, through the
platinum wire and back again to the battery through the gun thereby heating the wire
and firing the gun cotton and powder, this blows out a cork disc which closes an
opening formed in the end of the cap and fires the cartridge.
The cap may be of thin metal and a fresh one used each time that the primer is
recharged or it may be of stout metal and not require renewal.
In place of the platinuin wire being soldered to the front end of the central spindle
and to a pin projecting from the front end of the body it may be soldered to two
metallic pins carried by a disc of insulating material within the cap one pin at the
centre and the other near the periphery of the disc. When the cap is screwed on,
the pin at the centro comes into contact with the end of the central spindle and the
outer pin is connected by a spiral wire spring to the copper cap so that the electrical
connections are completed when the cap is screwed home.
In place of using a metallic cap to screw on to the end of the body the end of the
cavity in the body may as in the service primer be closed by a cylinder of cork or
other non-conducting material which has driven into it two brass pins-one into the
rear end to come against the end of the central spindle and the other into its side to
make contact with the body. In this case the bridge of platinum wire is soldered to
the heads of two pins.
The exterior of the primer may also be formed to the same pattern as the ordinary
service primer.
Data: 101
1007
°
CARPMAEL & Co.,
Agents for the Applicant.

page_text: I, GEORGE STUART, of the Elswick Works, Newcastle-on-Tyne, 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:-
This invention has for its object improvements in electrical primers. The primers
are mainly intended for use with axial vented guns more especially rapid fire guns.
They are of simple construction and possess the great advantage of being easily
renewed by being recharged and fitted with a new platinum wire and cap.
The primer is formed of a cylindrical metallic body by preference screwed on its
exterior to screw into the base of a cartridge case. At its rear end it is formed with
an enlarged head and its front end which is reduced in diameter has a screw cut
around its exterior for a copper cap to be screwed onto.
A cavity is formed centrally in the body from its front end nearly to its rear end.
From the rear end of the cavity is a passage of smaller diameter to the rear end of
the body. At the extreme rear end of this passage is also a shallow cavity of larger
diameter to receive a disc of ebonite or other non conducting material.
Inside of the main cavity formed in the body are placed discs of asbestos each
having a hole through its centre. A metallic spindle is passed centrally into the
cavity and through the holes in the asbestos discs and also made to extend through
the small passage at the rear end of the cavity. The spindle has a flange around it
to bear upon the discs of asbestos. More discs of asbestos are then inserted and
afterwards a metallic ring of gas check form. The ring and asbestos are then
subjected to a greater pressure than that produced in the gun. This forces the
asbestos into the small passage at the rear end of the cavity and forms it into a solid
insulating block. The ebonite insulator is then placed on to the rear end of the
metallic spindle the metallic spindle passing through it and also through a metallic
disc which is embedded in its rear end and finally the end of the spindle is rivetted
over. The front end of the metallic spindle has soldered to it a platinum wire which
is also soldered to a pin which projects from the front end of the body. The wire is
then surrounded with gun-cotton after which the cavity is filled with gun powder and
when the copper cap charged with gun cotton is screwed on to the front of the body
the primer is complete and ready for use.
On an electrical contact being made by means of an insulated rod passing through
the axial vent of a gun the electricity passes through the central spindle through the
platinum wire and back again to the battery through the gun thereby heating the
wire and firing the gun cotton and powder, this blows out a cork dise which closes an
opening formed in the end of the cap and fires the cartridge.
The cap may be of thin metal and a fresh one used each time that the primer is
recharged or it may be of stout metal and not require renewal.
In place of the platinum wire being soldered to the front end of the central spindle

page_text: and to a pin projecting from the front end of the body it may be soldered to two
metallic pins carried by a disc of insulating material within the cap one pin at the
centre and the other near the periphery of the disc. When the cap is screwed on,
the pin at the centre comes into contact with the end of the central spindle and the
outer pin is connected by a spiral wire spring to the copper cap so that the electrical
connections are completed when the cap is screwed home.
In place of using a metallic cap to screw on to the end of the body the end of the
cavity in the body may as in the service primer be closed by a cylinder of cork or
other non-conducting material which has driven into it two brass pins one into the
rear end to come against the end of the central spindle and the other into its side to
make contact with the body. In this case the bridge of platinum wire is soldered to
the heads of the two pins.
The exterior of the primer may also be formed to the same pattern as the ordinary
service primer.
The drawings hereunto annexed show the modified forms of the fuse above
described.
Figure 1 is a longitudinal section of the fuse.
Figures 2, 3, 4, 5 and 6 shew separate views of some of the parts of which it
is composed.
Figure 7 is a longitudinal section of a modified form of the fuse in which the front
end of the fuse is closed with a cap of solid metal.
Figures 8 shew an end view and longitudinal section of this cap and Figures 9
shew a face and edge view of the disc of cork carried by it.
Figure 10 is a longitudinal section of a modified form of the fuse in which the
means adopted for making electrical connections with the ends of the platinum
wire are modified. Figure 11 shews separately the central stem of this fuse.
Figures 12 shew the ebonite disc and platinum wire and metal pins carried by it-and
Figure 13 shews a separate view of the coiled spring.
Figure 14 is a longitudinal section of a modified form of the fuse in which the
front end of the fuse is closed in the way adopted in the ordinary service fuse.
Figures 15, 16 and 17 shew end and side views of the cylinder of cork which in this
fuse closes the end of the cavity C.
Figure 18 is a longitudinal section of the same fuse made of the same form or
pattern as the ordinary service fuse.
In Figures 1 to 6 A is the outer metallic body formed externally to screw into the
base of a cartridge case-and with its front end of reduced diameter and having a
screw thread cut around it for a metal cap B to screw onto. C is the central cavity
in the body A. D is a passage from the rear end of this cavity to another shallow
cavity at the rear end of the body. E is an ebonite disc placed in this latter cavity.
F is a metallic spindle passing centrally through the cavity C and through the ebonite
disc E. G is a metallic disc placed in a recess in the rear face of the ebonite disc E-
the spindle F passes through this disc G and is rivetted over as shown. H is the
packing of compressed asbestos filling the rear end of the cavity C and the passage Ꭰ
and surrounding the spindle F some of the packing being in rear of a collar Fi on
the spindle and some in front of it. H₁ is a dished metallic washer placed in front of
the asbestos packing. I is fine grained gunpowder contained in the front end of
the cavity C. J is a fine wire of platinum soldered at one end to the front of the
spindle F and at the other end to a metallic pin K which is inserted into a hole in the
front end of the body A. L is gun cotton surrounding the wire J and enclosed
in the cap B. M is a disc of cork which closes the hole in the front end of
the cap.
In the fuse shewn at Figures 7, 8 and 9 the construction is practically the same
and the parts are marked with the same letters of reference. The only difference is
that the cap B is made of thick in place of thin metal.
In the fuse shewn at Figures 10, 11, 12 and 13 the construction is the same except
that the platinum wire instead of being soldered to the end of the spindle F and to
the pin K is soldered to two metallic pins N carried by an ebonite disc O. The head

page_text: of one of these pins being in contact with the end of the spindle F and the other
being in contact with a coiled spring P which at one end is attached to the cap B.
The disc O has two small holes through it by which the flash from the gun cotton
surrounding the wire J may pass to the gun powder I.
In the fuse shewn at Figures 14, 15, 16 and 17 the end of the cavity C is closed
by a cylinder M of cork which has inserted into it two metallic pins N to which the
wire Jis soldered. The head of one of the pins comes in contact with the body A
and the head of the other with the end of the spindle F.
Figure 18 shows a longitudinal section of the same fuse but outwardly made of the
same form as the ordinary service fuse.
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. An electrical primer in which a tight joint is made around the rear end of the
central metallic stem by means of compressed asbestos substantially as described.
2. The herein before described combination of parts whereby a secure and gas
tight joint at the rear end of an electrical primer is obtained consisting of the body
of the primer having in it a longitudinal cavity extending from the front nearly to
the rear end a passage of smaller diameter extending to the rear end an insulated
metallic rod passing centrally through the passage and cavity and having upon it near
the rear end of the cavity a collar of larger diameter than the passage and a packing
of compressed asbestos or like material around the collar.
3. The construction of electrical primers substantially as herein before described
and illustrated in the drawings annexed.
Dated this 9th day of November 1887