Year: 1888

page_text: Date of Application (in United Kingdom), 27th July 1888
Complete Specification Left, 5th Apr., 1889
Complete Specification Accepted; 11th May, 1889
I, SELDEN ALLEN DAY, of Bowling Green, in the County of Wood, and State of
Ohio, United States of America, Captain in the United States Artillery, do hereby
declare the nature of this invention to be as follows:-
:
This invention relates to cartridges for electric guns and to electric primers or caps
or exploders applicable to cartridge shells in order to convert them into electric
cartridges. The invention relates partly to that class of electric cartridges employing
a high resistance wire or conductor in contact with the powder or fulminate and
which ignites the same upon being heated to incandescence by the passage of an
electric current. It also pertains to the mechanical construction of electric cartridges
in general, whether firing by means of an incandescent wire or by the passage of.
sparks between two adjacent conducting points.
Prior to my invention several different constructions of electric cartridges have
been devised both for firing by incandescence and by sparks. According to one
construction the cartridge is provided with a central or axial conducting pin extending
from the center of the base toward the front of the charge of powder, inclosed in a
tubular insulating sheath to insulate it from the base, said sheath fitting tightly in
the neck or seating at the base, with a conducting strip of metal extending from the
base along the outside of the sheath to the front thereof and a fine platinum wire
soldered at one end to said strip and at its other end to the front of the central
pin. This construction is the subject of a patent of the United States No. 307,071,
lated October 21, 1884, and of a patent in Great Britain No. 3505 of 1885 (dated
October 22, 1884).
According to another construction a metal tube fitting tightly over the exterior of
the insulating sheath is substituted for the strip of metal in the patent just referred
to, so that the insulating sheath has an inner electrode or leading-in conductor
within it consisting of a metal pin and an outer electrode or leading-in conductor.

page_text: exterior to it consisting of said metal tube, with the fine platinum wire soldered at one
end to the inner conductor and at the other end to the outer conductor. This con-
struction is described in a patent of the United States No. 319,627 granted June 9,
1885, to the American Electric Arms and Ammunition Company and in a patent of
Great Britain No. 3671 of 1885.
According to still another construction the tubular insulating sheath has a metal pin
within it and a metal tube exterior to it, this tube extending beyond the forward end
of the sheath in order to form a recess at the front end of the electric primer or
exploder for enclosing and protecting the fine platinum wire and for holding a portion
of powder. This construction is disclosed in a patent of the United States
No. 319,629, dated June 9, 1885, to the American Electric Arms and Ammunition
Company, and in the said British patent No. 3671 of 1885.
The cartridges shown in the two last mentioned United States patents are the most
perfect in construction of any electric cartridges heretofore devised so far as I am
aware. They are subject however in common with all central fire electric cartridges
the conductors or electrodes of which terminate at the base of the cartridge for
connection with the electrodes in the electric gun, the serious practical disadvantage
that the connection of the electric primer with the shell is not gas tight, so that the
cartridges rapidly deteriorate by firing and can consequently be used only once or
only a very small number of times, and the perfection of the electrical contacts or
connections is liable to be seriously impaired through oxidization by a local galvanic
action consequent upon the admission of moisture. The manufacture of such electric
cartridges or primers has also been attended with considerable difficulty and expense
owing to the necessity for joining the ends of the minute platinum wire to the front
ends of the respective inner and outer conductors or electrodes by the process of
soldering. This difficulty is increased by the construction of a recess at the front of
the primer to receive the platinum wire and as such a recess is of great practical
advantage it becomes highly desirable to provide some means of joining the ends of
the platinum wire which shall avoid the necessity for soldering.
The objects of my invention are to provide a construction for electric cartridges
or primers which shall render them gas tight and shall provide a cheap and effective
substitute for the soldering of the ends of the platinum or other highly resistant
wire or conductor, in order to cheapen the manufacture of the cartridges or primers
and render it possible to turn them out rapidly and in large quantities by means of
special machinery.
According to my invention I construct the electric primer or exploder with a tubular
insulating sheath, with an inner conductor within said sheath and a tubular outer
conductor surrounding said sheath, and, in the case of cartridges for firing by
incandescence, with a platinum wire or other equivalent high resistance conductor at
the front of the sheath making contact at one end with the inner and at the other
with the outer conductor, all in general similar in respect of its electrical features to
the constructions heretofore known. Instead however, of employing a solid metal pin
as the inner conductor. I employ a metallic cup of thin metal fitted tightly within the
sheath with its open side toward the front so that a powder chamber is formed within
the central conductor instead of being entirely in front of it as heretofore. When
the primer thus constructed is seated in the primer seat at the base of the shell the
cup acts upon being expanded by a pressure within it to force the intervening
insulating sheath outwardly into such close contact with the seat as to form a perfect.
check for the cartridge. As the cartridge shell and primer are successively used
the successive explosions expand the walls of the central metallic cup (which is
preferably made of copper) sufficiently each time to compensate for any looseness of
fit in the primer seat occasioned by the expansion of the seat or the compression of
the insulating sheath, so that the joint around the primer is kept gas tight and so close
as to prevent the entrance of moisture and the consequent deterioration of the
primer.
gas
In order to provide a suitable electrical connection between the opposite ends of the
platinum wire and the respective inner and outer conductors, I construct the primer

page_text: with one end of the platinum wire confined between the insulating sheath and the
inner conductor and with its other end confined between the sheath and the other
conductor, a sufficient length of the wire being extended into contact with the
respective conductors to ensure a suitable electrical contact between them. Since the
respective conductors are fitted very tightly within and without the insulating sheath,
the ends of the platinum wire are very tightly confined, whereby its attachment is
rendered secure and permanent. The insulating sheath is made longer than the
inner conductor, so that it projects further to the front and prevents contact between
the inner conductor and the portion of the platinum wire adjacent to its connection
with the outer conductor, whereby the short circuiting of the incandescing conductor
is avoided.
In order further to improve the electrical contact with the ends of the platinum
wire and render the primer more effectually moisture proof and more durable,
I flatten the platinum wire to an extremely thin ribbon so that an extended area of
contact surface is ensured between the respective end portions of the platinum
conductor and the respective outer and inner conductors or electrodes.
In the accompanying drawings which illustrate my invention in its preferred
and in certain modified forms the cartridges and primers represented are drawn to
magnified scales.
Figure 1 is a longitudinal mid-section of an electric cartridge and its primer
embodying the preferred construction of my invention. Fig. 1 is a corresponding
section of the forward part of the breech block of an electric gun showing the
respective electric terminals or electrodes and indicating in diagram the electrical circuit.
Fig. 2 is a longitudinal section of the empty shell of the cartridge shown in Fig. 1,
with the electric primer shown in elevation partly inserted therein.
Fig. 3 is a longitudinal mid-section on a larger scale of the construction of primer
shown in Fig. 1. Fig. 4 is a rear elevation of the primer shown in Fig. 3. Fig. 5
is a longitudinal mid-section of the several parts constituting this primer separated
from one another.
Figs. 6, 7, 8 and 9 show a slightly modified construction of primer, Fig. 6 being
a side elevation, Fig. 7 a front elevation. Fig. 8 a diametrical longitudinal section, and
Fig. 9 a rear elevation.
Fig. 10 is a perspective view illustrating the flattening of the high resistance
platinum wire and the formation of the incandescing conductor, the view being on a
much enlarged scale.
Fig. 11 is a longitudinal mid-section of a shot gun or sporting cartridge the
electric primer of which is constructed according to a modified adaptation of my
invention.
Fig. 12 is a longitudinal section of a cartridge shell, and Fig. 13 is a like section
of the electric primer therefor. Fig. 14 is a side elevation of this primer.
Figs. 1 and 16 are diametrical longitudinal sections of two different constructions
of primers illustrating a modification of my invention.
Fig. 17 is a longitudinal mid-section of a cartridge and primer embodying a
further modification.
Fig. 18 is a similar section of an electric cartridge for firing by means of electric
sparks, constructed according to one part of my invention.
Referring to the drawings let A designate the cartridge shell and B the electric
primer, or cap, or exploder, or igniter, therefor, as it may be variously termed.
The shell A is of the usual or any suitable construction. That shown in Figs. 1, 2
and 17 is a metallic shell, and that shown in Figs. 11 and 12 is a paper shell. In
either case the shell has a metallic base a, the central portion of which is turned
inwardly to form the usual neck or primer seat b.
The electric primer B consists of an inner metallic conductor or leading-in
electrode c, a tubular sheath d of insulating material and an outer metallic conductor
or leading-in electrode e, with a high resistance or incandescing conductor f
preferably of very fine platinum or iridio platinum wire. In the case of a cartridge
to be fired by electric sparks this high resistance wire will be omitted and in its

page_text: place conducting points or terminals will be arranged adjacent to each other for
the passage of the sparks between them.
Referring especially to Figs. 1 to 10 the primer B is constructed, according to
my invention, with the outer conductor e in the form of a thin metal tube into which
the insulating sheath d fits very tightly so as to require considerable force to drive
it in, and with the inner conductor c made in the form of a thin metal cup which
fits very tightly within the insulating sheath, being arranged with its open side
toward the front. The insulating sheath is made longer than this cup, so that
when they are united the sheath shall project beyond the front of the cup. The
outer tube e will also by preference be made longer than the sheath, so that it
shall project forward beyond both the sheath and cup.
The incandescing conductor f is made of a very fine platinum wire shown
magnified at f' in Fig. 10, which is first flattened by passing it between pressure
rolls into an extremely thin ribbon, as shown at fin Fig. 10, and is subsequently
bent into U-shape and cut off, as shown at fin Fig. 10. One of the turned back
arm (Fig. 10) of this conductor is inserted flatwise between the cup e and sheath b,
whereby this end of the conductor is connected electrically with the cup or inner
conductor c; and the other turned back arm f is inserted between the sheath d
and the outer tube e. whereby the other end of the incandescing conductor is
electrically connected with the outer conductor or tube e. The insertion of these
arms is effected during the forcing together of the parts c d and e. This operation
is preferably performed by first inserting one end of the flattened wire or ribbon f
(Fig. 10) within the sheath d and then forcing the cup c into the sheath, so as to
confine this end between the two; then the ribbon is drawn diametrically across the
sheath, and turned back against the exterior thereof; it is then cut off; and finally the
sheath is forced into the tube e, so that the outer end of the platinum ribbon is caught
and confined between the two. The platinum ribbon or wire is thus brought into
the position shown in Figs. 3 and 8 and extending diametrically across the front of the
primer and across the recess or powder space formed by the open interior of the
cup c and the forward extension thereof formed by the projection beyond the cup
of the insulating sheath. The platinum wire may be strained across this space or
not according to the method employed in its manufacture.
The flattening of the platinum wire not only enables it to be more easily and
conveniently manipulated during the putting together of the parts but also has the
great advantages of affording an extended contact surface against the respective
conductors cand e, so that it makes a good electrical contact therewith without undue
resistance so that the passage of the current between the platinum wire and these
conductors cannot oxidize either of them at their union and thereby impair their
connection; and also of taking very much less space between the insulating sheath
and the respective outer and inner conductors than would be occupied by a round
wire, so that the sheath and conductors are not forced apart so far as to in the least
impair their fit or form interstices for the admission of moisture or gases, whereby
the tightness of the primer is ensured and it is enabled to resist the influence of
moisture. Electric cartridges thus constructed have been buried in the earth for
several months in a moist place without being in the least deteriorated thereby. The
flattening of the platinum wire also seems to have the effect of enabling it to withstand
the heat caused by the passage of the electric current through it for a longer time
than the round wire, so that it makes a primer which can be fired a greater number
of times before burning itself out, a result that 1 attribute to the greater radiating
surface of the flattened wire, since the resistance of the wire is the same after being
flattened as before.
The outer tube e of the primer is made a tight and exact fit with the neck or primer
seat of the cartridge shell, so that considerable pressure is required to force it into
place therein. In the filling of the shell the powder enters within the recess in the cup c
and surrounds the platinum wire on all sides. When the electrical current is passed
through the platinum wire and heats the latter the powder in contact with it is ignited
and burns outwardly from the front of the primer and also inwardly within the cup c,

page_text: so that instantly a gaseous pressure is generated within this cup, which serves to
expand its walls closely against the insulating sheath and to expand the latter and the
tube e against the primer seat, whereby the joints between the respective parts are
kept gas tight, so that the escape of gas from the cartridge is prevented and the
leakage of gaseous corrosive agents into contact with the electrical connections,
whereby the latter might be corroded and a perfect contact impaired, is avoided.
The tube e may terminate close to the front of the insulating sheath, as shown in
Figs 6, 7 and 8, in which case the charge of powder in the cartridge will be ignited
at the rear and will burn thence forward. It is preferable however, to form the tube e
with a forward extension e¹ as shown in Figs. 1 to 5, in order to form a deep powder
chamber, as indicated in Fig. 1, so that the powder in this chamber will burn forward
through the tube e and ignite the main portion of the charge of powder at the front
of this tube, from which point it will burn backward to the rear of the charge as well
as forward. The tube ¹ may be made of any length desired in order to ignite the
main charge nearer to or further from the front thereof. My improved means for
joining the ends of the platinum wire is especially advantageous in this construction,
since it would be practically impossiblo to join the ends by soldering when the wire
was arranged far within the tube, or in so deep a recess or chamber. Hereto-
fore it has been necessary in order to carry the fire forward into the charge, to arrange
the platinum wire at the front of the primer, a construction which is inferior to that
provided by my invention as illustrated in Figs. 1 to 5 in that there is no oppor-
tunity for the construction of a gas check since the portion of the primer to the rear
of the wire has had heretofore to be made solid; and in that the wire is more
exposed to injury and the primer consequently cannot be used as many times as
when it is arranged near the bottom of a deep recess or cavity. In either construc-
tion it is preferable to form the tube e with a slight contraction at its forward end in
order to embrace and partly enclose the front end of the sheath, and limit the forward
movement of the sheath in putting the parts together. The front of the sheath may
also advantageously be turned in to slightly lap over and protect the forward end
or edge of the cup c.
An electric gun for firing the cartridge thus constructed must have at its breech
block two electrodes or terminals in connection with the opposite poles of a galvanic
battery or other generator of an electric current, and means for closing the circuit
between said battery and the electrodes ce of the cartridge primer after the cartridge
has been placed in the gun. Fig. 1 shows the construction of the breech block, and
one means for closing the electric circuit to fire the cartridge. The breech block C
itself constitutes one electrode, and the other electrode consists of a metal pin D
arranged in iine with the axis of the cartridge, so that when the latter is in place
with its base a against the block C the circuit will be closed by pushing forward the
pin D (by pulling the trigger of the gun) until its front end touches the cup c, where-
upon the current will flow through the pin D, cup c, platinum wire f, and tube e
and base a into the breech block Cand thence back to the battery. The firing pin D
is insulated from the breech block by a plug i of insulating material such as bone or
other hard substance, which must be of sufficiently large diameter to cover the rear
of the cup c and prevent any portion of the latter coming in contact with the breech
block C. as thereby the primer would be short circuited.
It will be observed that after the primer B has been inserted in the cartridge shell
its outer tube e stands in close and intimate contact with the neck or primer seat b,
so that both electrically and mechanically these two tubular parts constitute substan-
tially but one part. The only reason for employing both tubes c and b is to construct
the primer B complete in itself so that it can be made a distinct article of sale in the
same manner that percussion caps are, without liability of injuring it or rendering it
inoperative either in packing, transit, or storage, or in the operation of inserting it
into the cartridge shell. Otherwise the tube e might be omitted and the primers sold
to consumers with only the parts cb and f, but if so sold the outer end of the platinum
wire would project out loosely and unattached, and be liable, owing to its extreme
fragility, to become pulled out or injured. But in those cases where the cartridges

page_text: are manufactured complete at a factory it is preferable to omit the tube e and
construct the neck b of the cartridge shell to take its place.
Such a construction is shown in Figs. 11 to 14. In Fig. 11 the nec: b is short,
answering to the tubs e in Figs. 6 to S, while in Fig. 12 the neck is prolonged
forward into the charge of powder forming the tubular extension found in the
constructions shown in Figs. 1 to 5. In Fig. 12 the shell is shown empty, the primer
not having yet been inserted. The primer is shown in Figs. 13 and 14. It will be
seen from these figures that the outer tube e is omitted from it, so that the outer end
of the platinum wire is free or unattached. To complete the primer it is forced into
the neck which constitutes the outer tube or conductor e of the primer, the primer
being shown thus inserted in Fig. 11. The primers might be sold to consumers in
the condition shown in Figs. 13 and 14 were it not for the inconvenience and liability
to injury that might result from the outer end of the platinum wire being left free.
This difficulty however, might be overcome by cementing the platinum wire to the
exterior of the insulating sheath. The friction against the platinum wire in the act of
inserting the primer will suffice to brighten its surface and make a good electrical
connection.
The feature of my invention which pertains to the fastening of the ends of the
platinum wire may be used without the feature of the inner conductor being made in
the form of a cup to form a gas check. Figs. 15 and 16 show a primer wherein the
inner conductor c is a solid block or button of metal instead of being made a sheet
metal cup. This block may be hollowed out at its front end as shown in Fig. 15, to
deepen the powder recess behind the platinum wire and prevent liability of short
circuiting that wire by its being pressed back into contact with the front of the
block c; or the block may be made without such recess, as shown in Fig. 16. In the
latter case the recess through which the platinum wire crosses is formed solely by
the projection of the insulating sheath beyond the front of the inner conductor c,
whereas in the former case and in the construction shown in the previous figures there
is in addition to such recess a further cavity in the conductor c itself, and the platinum
wire crosses entirely in front of this latter cavity.
Fig. 17 shows a construction wherein the inner conductor c is prolonged forward
and made solid, being substantially a pin, and the insulating sheath is prolonged
considerably beyond this pin to form a suitable deep recess for the platinum wire."
The feature of my invention which provides u gas check for electric cartridges
or primers is applicable to those cartridges which fire by an electric spark as well
as to those employing an incandescing wire. Fig. 18 shows this feature of my inven-
tion as applied to a spark fire cartridge. The cup c and sheath d are constructed
the same as already described with reference to Figs. 3 and 5 for example, and the
sheath fits tightly. into the neck 6 of the shell. A post his fastened axially within
the cup c, by riveting its rear end to the center of the cup, as shown, or other-
wise, and this post has an arm or finger projecting to one side and approaching
close to the edge of the neck b so that electric sparks may pass between this point
and the edge of the neck, thereby igniting the intervening gun-powder. The
powder will enter the recess or cavity in the cup c and in exploding will expand
the
cup and form a gas check.
My invention will be in part availed of if in a cartridge or primer having an
incandescing conductor f only one end of such conductor is confined between the
insulating sheath and one or other of the leading-in conductors or electrodes c
and e (or b) the other end of the incandescing conductor being fastened by soldering
or otherwise.
Dated thin 97th dose of I... 1000

page_text: COMPLETE SPECIFICATION.
Improvements in Electric Cartridges and Primers.
I, SELDEN ALLEN DAY, of Bowling Green, in the County of Wood, and State of
Ohio, United States of America, Captain in the United States Army, do hereby
declare the nature of this invention and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement, viz:
This invention relates to cartridges for electric guns and to electric primers or
caps or exploders applicable to cartridge shells in order to convert them into electric
cartridges. The invention relates particularly to that class of electric cartridges
employing a high resistance wire or conductor in contact with the powder or fal ninate
and which ignites the same upon being heated to incandescence by the passage of an
electric current. It also pertains to the mechanical construction of electric cartridges
in general, whether firing by means of an incandescent wire or by the passage of
sparks between two adjacent conducting points.
Prior to my invention several different constructions of electric cartridges have
been devised both for firing by incandescence and by sparks. According to one
construction the cartridge is provided with a central or axial conducting pin extending
from the center of the base toward the front of the charge of powder, inclosed in a
tubular insulating sheath to insulate it from the base, said sheath fitting tightly in
the neck or seating at the base, with a conducting strip of metal extending from the
base along the outside of the sheath to the front thereof and a fine platinum wire
soldered at one end to said strip and at its other end to the front of the central pin.
This construction is the subject of a patent of the United States No. 307,071, dated
October 21, 1884, and of a patent in Great Britain No. 3505 of 1885 (dated
October 22, 1884).
According to another construction a metal tube fitting tightly over the exterior of
the insulating sheath is substituted for the strip of metal in the patent just referred
to, so that the insulating sheath has an inner electrode or leading-in conductor
within it consisting of a metal pin and an outer electrode or leading-in conductor
exterior to it consisting of said metal tube, with the fine platinum wire soldered at
one end to the inner conductor and at the other end to the outer conductor. This
construction is described in a patent of the United States No. 319,627, granted
June 9, 1885, to the American Electric Arms and Ammunition Company and in a
patent of Great Britain No. 3671 of 1885.
According to still another construction the tubular insulating sheath has a metal
pin within it and a metal tube exterior to it, this tube extending beyond the forward
end of the sheath in order to form a recess at the front end of the electric primer or
exploder for enclosing and protecting the fine platinum wire and for holding a
portion of powder. This construction is disclosed in a patent of the United States
No. 319,629, dated June 9, 1885, to the American Electric Arms and Ammunition
Company, and in the said British patent No. 3671 of 1885.

page_text: The cartridges shown in the last mentioned British patent are the most perfect in
construction of any electric cartridges heretofore devised so far as I am aware.
They are subject however in common with all central fire electric cartridges the
conductors or electrodes of which terminate at the base of the cartridge for con-
nection with the electrodes in the electric gun, to the serious practical disadvantage
that the connection of the electric primer with the shell is not gas tight, so that the
cartridges rapidly deteriorate by firing and can consequently be used only once or
only a very small number of times, and the perfection of the electrical contacts or
connections is liable to be seriously impaired through oxidization by a local galvanic
action consequent upon the admission of moisture. The manufacture of such electric
cartridges or primers has also been attended with considerable difficulty and expense
owing to the necessity for joining the ends of the minute platinum wire to the front
ends of the respective inner and outer conductors or electrodes by the process of
soldering. This difficulty is increased by the construction of a recess at the front
of the primer to receive the platinum wire and as such a recess is of great practical
advantage it becomes highly desirable to provide some means of joining the ends of
the platinum wire which shall avoid the necessity for soldering.
The objects of my invention are to provide a construction for electric cartridges
or primers which shall render them gas tight and shal! provide a cheap and effective
substitute for the soldering of the ends of the platinum or other highly resistant wire
or conductor, in order to cheapen the manufacture of the cartridges or primers and
render it possible to turn them out rapidly and in large quantities by means of special
machinery.
According to my invention I construct the electric primer or exploder with a
tubular insulating sheath, with an inner conductor within said sheath and a tubular
outer conductor surrounding said sheath, and, in the case of cartridges for firing by
incandescence, with a platinum wire or other equivalent high resistance conductor at
the front of the sheath making contact at one end with the inner and at the other
with the outer conductor, all in general similar in respect of its electrical features
to the constructions heretofore known. Instead however, of employing a solid metal
pin as the inner conductor, 1 employ a metallic cup of thin metal fitted tightly
within the sheath with its open side toward the front so that a powder chamber is
formed within the central conductor instead of being entirely in front of it as here
tofore. When the primer thus constructed is seated in the primer seat at the base
of the shell the cup acts upon being expanded by a pressure within it to force the
intervening insulating sheath outwardly into such close contact with the seat as to
form a perfect gas check for the cartridge. As the cartridge shell and primer are
successively used the successive explosions expand the walls of the central metallic
cup (which is preferably made of copper) sufficiently each time to compensate for
any looseness of fit in the primer seat occasioned by the expansion of the seat or the
compression of the insulating sheath, so that the joint around the primer is kept gas
tight and so close as to prevent the entrance of moisture and the consequent
deterioration of the primer.
In order to provide a suitable electrical connection between the opposite ends of
the platinum wire and the respective inner and outer conductors, I construct the
primer with one end of the platinum wire confined between the insulating sheath and
the inner conductor and with its other end confined between the sheath and the outer
conductor, a sufficient length of the wire being extended into contact with the respec-
tive conductors to ensure a suitable electrical contact between them. Since the
respective conductors are fitted very tightly within and without the insulating
sheath, the ends of the platinum wire are very tightly confined, whereby its attach-
ment is rendered secure and permanent. The insulating sheath is made longer than
the inner conductor, so that it projects further to the front and prevents contact
between the inner conductor and the portion of the platinum wire adjacent to its
connection with the outer conductor, whereby the short circuiting of the incandescing
conductor is avoided.
In order further to improve the electrical contact with the ends of the platinum

page_text: wire and render the primer more effectually moisture proof and more durable, I
flatten the platinum wire to an extremely thin ribbon so that an extended area of
contact surface is ensured between the respective end portions of the platinum con-
ductor and the respective outer and inner conductors or electrodes.
In the drawings accompanying my Provisional Specification and which illustrate my
invention in its preferred and in certain modified forms the cartridges and primers
represented are drawn to magnified scales.
Figure 1 is a longitudinal mid-section of an electric cartridge and its primer
embodying the preferred construction of my invention. Fig. 1 is a corresponding
section of the forward part of the breech block of an electric gun showing the
respective, electric terminals or electrodes and indicating in diagram the electrical
circuit.
Fig. 2 is a longitudinal section of the empty shell of the cartridge shown in
Fig. 1, with the electric primer shown in elevation partly inserted therein.
Fig. 3 is a longitudinal mid-section on a larger scale of the construction of primer
shown in Fig. 1. Fig. 4 is a rear elevation of the primer shown in Fig. 3. Fig. 5
is a longitudinal mid-section of the several parts constituting this primer separated
from one another.
Figs. 6, 7, 8 and 9 show a slightly modified construction of primer, Fig. 6 being
a side elevation, Fig. 7 a front elevation, Fig. 8 a diametrical longitudinal section,
and Fig. 9 a rear elevation.
Fig. 10 is a perspective view illustrating the flattening of the high resistance
platinum wire and the formation of the incandescing conductor, the view being on a
much enlarged scale.
Fig. 11 is a longitudinal mid-section of a shot gun or sporting cartridge the
electric primer of which is constructed according to a modified adaptation of my
invention.
Fig. 12 is a longitudinal section of a cartridge shell, and Fig. 13 is a like
section of the electric primer therefor. Fig. 14 is a side elevation of this primer.
Figs. 15 and 16 are diametrical longitudinal sections of two different constructions
of primers illustrating a modification of my invention.
Fig. 17 is a longitudinal mid-section of a cartridge and primer embodying a further
modification.
Fig. 18 is a similar section of an electric cartridge for firing by means of electric
sparks, constructed according to one part of my invention.
Referring to the drawings let A designate the cartridge shell and B the electric
primer, or cap, or exploder, or igniter, therefor, as it may be variously termed.
The shell A is of the usual or any suitable construction. That shown in Figs. 1,
2 and 17 is a metallic shell, and that shown in Figs. 11 and 12 is a paper shell. In
either case the shell has a metallic base a, the central portion of which is turned
inwardly to form the usual neck or primer seat b.
The electric primer B consists of an inner metallic conductor or leading-in
electrode c, a tubular sheath d of insulating material and an outer metallic conductor
or leading-in electrode e, with a high resistance or incandescing conductor f,
preferably of very fine platinum or iridio platinum wire. In the case of a cartridge
to be fired by electric sparks this high resistance wire will be omitted and in its place
conducting points or terminals will be arranged adjacent to each other for the
of the sparks between them.
passage
Referring especially to Figs. 1 to 10 the primer B is constructed, according to my
invention, with the outer conductor e in the form of a thin metal tube into which
the insulating sheath d fits very tightly so as to require considerable force to drive it
in, and with the inner conductor c made in the form of a thin metal cup which fite
very tightly within the insulating sheath, being arranged with its open side toward
the front. The insulating sheath is made longer than this cup, so that when they
are united the sheath shall project beyond the front of the cup. The outer tubo e
will also by preference be made longer than the sheath, so that it shall project forward
beyond both the sheath and cup.

page_text: The incandescing conductor fis made of a very fine platinum wire shown magnified
at in Fig. 10, which is first flattened by passing it between pressure rolls into
an extremely thin ribbon, as shown at f in Fig. 10, and is subsequently bent into
U-shape and cut off, as shown at fin Fig. 10. One of the turned back arms f
(Fig, 10) of this conductor is inserted flatwise between the cup c and sheath b,
whereby this end of the conductor is connected electrically with the cup or inner
conductor c; and the other turned back arm f³ is inserted between the sheath d and
the outer tube e, whereby the other end of the incandeseing conductor is electrically
connected with the outer conductor or tube e. The insertion of these arms is
effected during the forcing together of the parts c d and e. This operation is prefer-
ably performed by first inserting one end of the flattened wire or ribbon f* (Fig. 10)
within the sheath d and then forcing the cup c into the sheath, so as to confine this
end between the two; then the ribbon is drawn diametrically across the sheath, and
turned back against the exterior thereof; it is then cut off; and finally the sheath is
forced into the tube e, so that the outer end of the platinum ribbon is caught and
confined between the two. The platinum ribbon or wire is thus brought into the
position shown in Figs. 3 and 8 and extending diametrically across the front of the
primer and across the recess or powder space formed by the open interior of the cup c
and the forward extension thereof formed by the projection beyond the cup of the
insulating sheath. The platinum wire may be strained across this space or not
according to the method employed in its manufacture.
The flattening of the platinum wire not only enables it to be more easily and con-
veniently manipulated during the putting together of the parts but also has the
great advantages of affording an extended contact surface against the respective
conductors c and e, so that it makes a good electrical contact therewith without undue
resistance so that the passage of the current between the platinum wire and these
conductors cannot oxidize either of them at their union and thereby impair their
connection; and also of taking very much less space between the insulating sheath
and the respective outer and inner conductors than would be occupied by a round
wire, so that the sheat!: and conductors are not forced apart so far as to in the least
impair their fit or form interstices for the admission of moisture or gases, whereby
the tightness of the primer is ensured and it is enabled to resist the influence of
moisture. Electric cartridges thus constructed have been buried in the earth for
several months in a moist place without being in the least deteriorated thereby. The
flattening of the platinum wire also seems to have the effect of enabling it to with-
stand the heat caused by the passage of the electric current through it for a longer
time than the round wire, so that it makes a primer which can be fired a greater
number of times before burning itself out, a result that I attribute to the greater
radiating surface of the flattened wire, since the resistance of the wire is the same
after being flattened as before.
The outer tube e of the primer is made a tight and exact fit with the neck or
primer seat 6 of the cartridge shell, so that considerable pressure is required to force
it into place therein. In the filling of the shell the powder enters within the recess
in the cup c, and surrounds the platinum wire on all sides. When the electrical
current is passed through the platinum wire and heats the latter the powder in con-
tact with it is ignited and burns outwardly from the front of the primer and also
inwardly within the cup c, so that instantly a gaseous pressure is generated within
this cup, which serves to expand its walls closely against the insulating sheath and to
expand the latter and the tube e against the primer seat, whereby the joints between the
respective parts are kept gas tight, so that the escape of gas from the cartridge is
prevented and the leakage of gaseous corrosive agents into contact with the electrical
connections, whereby the latter might be corroded and a perfect contact impaired, is
avoided.
'3
The tube e may terminate close to the front of the insulating sheath, as shown in
Figs. 6, 7 and 8, in which case the charge of powder in the cartridge will be ignited
at the rear and will burn thence forward. It is preferable however, to form the
tube e with a forward extension e as shown in Figs. 1 to 5, in order to form a deep

page_text: powder chamber, as indicated in Fig. 1, so that the powder in this chamber will
burn forward through the tube e and ignite the main portion of the charge of powder
at the front of this tube, from which point it will burn backward to the rear of the
charge as well as forward. The tube e¹ may be made of any length desired in order
to ignite the main charge nearer to or further from the front thereof. My improved
means for joining the ends of the platinum wire is especially advantageous in this
construction, since it would be practically impossible to join the ends by soldering
when the wire was arranged so far within the tube, or in so deep a recess or chamber.
Heretofore it has been necessary in order to carry the fire forward into the charge,
to arrange the platinum wire at the front of the primer, a construction which is
inferior to that provided by my invention as illustrated in Figs. 1 to 5 in that there
is no opportunity for the construction of a gas check since the portion of the primer
to the rear of the wire has had heretofore to be made solid; and in that the wire is
more exposed to injury and the primer consequently cannot be used as many times
as when it is arranged near the bottom of a deep recess or cavity. In either con-
struction it is preferable to form the tube e with a slight contraction at its forward
end in order to embrace and partly enclose the front end of the sheath, and limit
the forward movement of the sheath in putting the parts together. The front of the
sheath may also advantageously be turned in to slightly lap over and protect the
forward end or edge of the cup c.
An electric gun for firing the cartridge thus constructed must have at its breech
block two electrodes or terminals in connection with the opposite poles of a galvanic
battery or other generator of an electric current, and means for closing the circuit
between said battery and the electrodes ce of the cartridge primer after the cartridge
has been placed in the gun. Fig. 1 shows the construction of the breech block,
and one means for closing the electric circuit to fire the cartridge. The breech
block Citself constitutes one electrode, and the other electrode consists of a metal
pin D arranged in line with the axis of the cartridge, so that when the latter is in
place with its base a against the block C the circuit will be closed by pushing forward
the pin D (by pulling the trigger of the gun) until its front end touches the cup c,
whereupon the current will flow through the pin D, cup c, platinum wire f, and
tube e and base a into the breech block C and thence back to the battery. The
firing pin D is insulated from the breech block by a plug i of insulating material
such as bone or other hard substance, which must be of sufficiently large diameter to
cover the rear of the cup c and prevent any portion of the latter coming in contact
with the breech block C, as thereby the primer would be short circuited.
It will be observed that after the primer B has been inserted in the cartridge shell
its outer tube e stands in close and intimate contact with the neck or primer seat b,
so that both electrically and mechanically these two tubular parts constitute sub-
stantially but one part. The only reason for employing both tubes e and b is to
construct the primer B complete in itself so that it can be made a distinct article of
sale in the same manuer that percussion caps are, without liability of injuring it or
rendering it inoperative either in packing, transit, or storage, or in the operation of
inserting it into the cartridge shell. Otherwise the tube e might be omitted and
the primers sold to consumers with only the parts c b and f, but if so sold the outer
end of the platinum wire would project out loosely and unattached, and be liable,
owing to its extreme fragility, to become pulled out or injured. But in those cases
where the cartridges are manufactured complete at a factory it is preferable to omit
the tube e and construct the neck 6 of the cartridge shell to take its place.
Such a construction is shown in Figs. 11 to 14. In Fig. 11 the neck b is short,
answering to the tube e in Figs. 6 to 8, while in Fig. 12 the neck is prolonged
forward into the charge of powder forming the tubular extension e¹ found in the
constructions shown in Figs. 1 to 5. In Fig. 12 the shell is shown empty, the
primer not having yet been inserted. The primer is shown in Figs. 13 and 14. It
will be seen from these figures that the outer tube e is omitted from it, so that the
outer end of the platinum wire is free or unattached. To complete the primer it is
forced into the neck 6 which constitutes the outer tube or conductor e of the primer,

page_text: the primer being shown thus inserted in Fig. 11. The primers might be sold to
consumers in the condition shown in Figs. 13 and 14 were it not for the incon-
venience and liability to injury that might result from the outer end of the platinum
wire being left free. This difficulty however, might be overcome by cementing the
platinum wire to the exterior of the insulating sheath. The friction against the
platinum wire in the act of inserting the primer will suffice to brighten its surface
and make a good electrical connection.
The feature of my invention which pertains to the fastenings of the ends of the
platinum wire may be used without the feature of the inner conductor being made
in the form of a cup to form a gas check. Figs. 15 and 16 show a primer wherein
the inner conductor c is a solid block or button of metal instead of being made a
sheet metal cup. This block may be hollowed out at its front end as shown in Fig. 15,
to deepen the powder recess behind the platinum wire and prevent liability of short
circuiting that wire by its being pressed back into contact with the front of the
block c; or the block may be made without such recess, as shown in Fig. 16. In
the latter case the recess through which the platinum wire crosses is formed solely by
the projection of the insulating sheath beyond the front of the inner conductor c,
whereas in the former case and in the construction shown in the previous figures
there is in addition to such recess a further cavity in the conductor c itself, and the
platinum wire crosses entirely in front of this latter cavity.
Fig. 17 shows a construction wherein the inner conductor c is prolonged forward
and made solid, being substantially a pin, and the insulating sbeath is prolonged
considerably beyond this pin to form a suitable deep recess for the platinum wire.
The feature of my invention which provides a gas check for electric cartridges or
primers is applicable to those cartridges which fire by an electric spark as well as to
those employing an incandescing wire. Fig. 18 shows this feature of my invention
as applied to a spark fire cartridge. The cup c and sheath d are constructed the
same as already described with reference to Figs. 3 and 5 for example, and the
sheath fits tightly into the neck b of the shell. A post his fastened axially within
-the cup c, by riveting its rear end to the center of the cup, as shown, or otherwise,
and this post has an arm or finger projecting to one side and approaching close to
the edge of the neck b so that electric sparks may pass between this point and the
edge of the neck, thereby igniting the intervening gun-powder. The powder will
enter the recess or cavity in the cup c and in exploding will expand the cup and form
a gas check.
My invention will be in part availed of if in a cartridge or primer having an
incandescing conductor f only one end of such conductor is confined between the
insulating sheath and one or other of the leading-in conductors or electrodes c and e
(or b) the other end of the incandescing conductor being fastened by soldering or
otherwise.
Having now fully described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. In an electric primer or cartridge the combination of a metal cup arranged
with its open side toward the front and adapted to constitute one of the electrodes of
the cartridge, with a tubular insulating sheath around said cup. adapted in use to
electrically separate said cup from the other electrode of the cartridge, whereby in the
firing of the cartridge the sides of said cup are adapted to expand and force the
insulating sheath against the primer seat to form a gas check.
2. The combination with a cartridge shell having a turned in neck to form a
primer seat, of a metal cup placed in said seat with its open side toward the front,
and an insulating sheath intervening between said cup and neck.
3. The combination to form an electric primer of a tubular insulating sheath, a
conductor within it consisting of a metal cup arranged with its open side toward the
front, and an outer conductor consisting of a metal tube surrounding said sheath and
electrically separated thereby from said cup.

page_text: 4. In an electric primer or cartridge the combination of a tubular insulating
sheath, an inner metallic conductor within said sheath, an outer metallic conductor
exterior to said sheath, and an incandescing conductor having one end confined
between the sheath and one of said conductors and its other end electrically connected
to the other of said conductors.
5. In an electric primer or cartridge, the combination of a tubular insulating
sheath, an inner metallic conductor within said sheath, an outer metallic conductor
exterior to said sheath, and an incandescing conductor having its one end confined
between the sheath and the inner conductor, and its other end confined between the
sheath and the outer conductor, whereby its ends are brought into electrical connection
with said conductors.
6. The combination to form an electric primer of a tubular insulating sheath, a
tubular outer metallic conductor surrounding said sheath, an inner metallic conductor
enclosed by said sheath and of less length than the sheath, so that the latter projects
forward beyond it and forms a recess, and an incandescing conductor having its one
end confined between the sheath and the inner conductor and its other end confined
between the sheath and the outer conductor, and arranged to cross said recess.
7. The combination to form an electric primer of a tubular insulating sheath, a
tubular outer metallic conductor surrounding said sheath, an inner metallic conductor
enclosed by said sheath and recessed on its forward side to form a powder cavity and
an incandescing conductor having its one end confined between the sheath and the
inner conductor and its other end confined between the sheath and the outer conductor,
and arranged to cross in front of said powder cavity.
8. In an electric cartridge or primer the combination of a tubular insulating
sheath, an inner metallic conductor within said sheath, an outer metallic conductor
exterior to said sheath, and an incandescing conductor consisting of a fine wire baving
a flattened end confined flatwise between the sheath and one of said conductors and
its other end electrically connected to the other of said conductors.
9. The combination to form an electric primer of a tubular insulating sheath, an
inner metallic conductor within said sheath, an outer metallic conductor exterior to
said sheath, and an incandescing conductor having the form of a flat ribbon, and
arranged with its one end confined flatwise between the sheath and the inner
conductor, and its other end confined flatwise between the sheath and the outer
conductor.
n
11
001 1
Mh 1000
J. C. MEWBURN,
55 & 56, Chancery Lane, London,
Patent Agent.