New or Improved Electrical Primers and Electrical Frictional Primers.
Year: 1890

page_text: COMPLETE SPECIFICATION.
New or Improved Electrical Primers and Electrical Frictional
Primers.
I ALFRED LONGSDON, of 9 New Broad Street in the City of London, Civil
Engineer, do hereby declare the nature of this invention, (a communication to me,
from the firm of Fried. Krupp of Essen in the Empire of Germany Cast Steel
Manufacturers), and in what manner the same is to be performed, to be particularly
described and ascertained in, and by, the following statement:-
This invention relates to electrical priming screw plugs for discharging ordnance,
establishing at the same time a perfect tightening against the backward escape of the
powder gases.
The accompanying drawings show the electrical priming screw plug, and the
electrical frictional priming screw plug, constructed according to the invention.
Fig. A illustrates in sectional elevation and plan the electrical priming screw plug
containing a central insulated metallic wire a, provided near its inner end with a
cylindrical boss b, a pasteboard obturator plate or disc c, a primer d, the charge e of
grained powder, and the platinum wire f, one end of which is fixed to the metallic wire,
and the other end soldered to the body of the priming screw plug.
By means of this arrangement of priming screw plug, the piece of ordnance can
only be discharged by electricity.
Fig. B shows in sectional elevation, and plan, an electrical frictional priming
screw plug, the construction of which is similar to that of the priming screw
plug, illustrated in Fig. A, excepting that it differs from the latter in the following
parts.
a. The friction wire is provided at its lower end with a friction surface g, which
when the said friction wire is drawn through the primer, the latter is caused to explode.
b. The central bore of the priming screw plug is longer, and allows the friction
wire with its cylindrical boss, to be drawn into it and through the primer.
The electrical frictional priming screw illustrated at Fig. B, allows the piece of
ordnance to be discharged by electricity, as well as by hand.
To the electrical priming screw plug, and to the frictional priming screw plug
respectively belong the following parts.
1. The body of the screw plug s, the head being made of brass or of any other
suitable material. The screw plug contains the different parts of the priming
apparatus, and keeps them at the proper distances from each other, protecting
them at the same time against damage and humidity.
2. The metallic or friction wire a is of brass or any other suitable material. Its
end outside the priming screw plug is bent so as to form an eye; near its other end
the wire a is provided with a cylindrical boss b. The wire of the frictional priming
screw plug is moreover provided at its lower end, with a friction surface g.
The metallic or friction wire is insulated, above the cylindrical boss, by a suitable
covering spun over it and by a coating of wax, and it is fastened to the head of the
screw plug, by means of packthread, so as to prevent it from turning in the priming
screw plug, whereby the platinum wire would be broken.
3. The primer d, which in the two screw plugs is of the same construction, is
pressed into a paper case and applied to the friction wire immediately underneath the
cylindrical boss.
The primer has for its purpose to increase, in the priming screw plugs, the fire jet
of the powder charge, and besides in the priming screw plug illustrated at Fig. R, to
cause the explosion when the friction wire is drawn through the primer.
4. The charge e of grained powder, provided with a closure plate of
by means of shellac. In this charge of grained powder there is lodged-
5. The platinum wire f, connected with the central wire and the body of priming
paper fastened

page_text: screw plug. By closing the electric circuit, the platinum wire fis made to glow thus
igniting the powder charge.
6. The plate or disc c made of pasteboard or of any other suitable substance,
having (in the two priming screw plugs) for its object to form a perfect tightening
against the powder-gases, and moreover in the screw plug shown at Fig. A, to insulate
the cylindrical boss of the metal wire from the body of the screw plug. The plate or
disc c is coated with shellac before being inserted.
For discharging a gun by electricity, the electrical priming screw plug, or the
electrical frictional priming screw plug. is screwed into the rear part of the vent
piece, which for this purpose is provided with a screw-thread and bearing for the
priming screw plug, to such depth, that the front end thereof bears tightly against
the corresponding shoulder in the vent piece. The breech block is arranged in
such a manner, that the priming screw plug can be screwed in, or withdrawn,
the breech block being open or closed.
For conducting the electric current to the gun, two insulated wires are employed,
one of which is connected with one of the scale holders, or with another part of
the gun. The other conducting wire is hooked, when the breech block is closed,
into the eye of the electrical priming screw plug, or the electrical frictional
priming screw plug.
At this moment the electrical circuit must still be open.
On the command "fire" the electric circuit is closed. By this, the platinum
wire begins to glow, and ignites the charge e of grained powder. The fire jet
of the latter, increased by that of the primer, will cause the charge of the piece
of ordnance to explode.
Should the electrical discharge fail to act, the electrical frictional priming
screw plug illustrated in Fig. B, allows the piece of ordnance to be discharged
by hand, and in the same manner as with the ordinary frictional priming screw
plugs. For firing the electrical priming screw plug by hand, the packthread by
means of which the friction wire is fastened to the head of the priming screw plug,
must be cut beforehand.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is
First. The electrical priming screw plug, composed of a body, a central insulated
metallic wire having near its inner end a cylindrical boss, a plate or disc of paste-
board, or of any other suitable material, forming a perfect tightening against the
powder gases, and also an insulator, a primer, a charge of grained powder with
closure plate, and a platinum wire, one end of the latter being fastened to the inner
end of the metallic wire, and the other end soldered to the body of the priming
screw plug, all substantially as and for the purposes herein described with especial
reference to Figure A of the accompanying drawings.
Second. The electrical frictional priming screw plug, composed of a body, a central
insulated metallic wire, having near its inner end a cylindrical boss, a plate or disc
of pasteboard or of any other suitable material forming a perfect tightening against
the powder gases, a primer, a charge of grained powder with closure plate, and a
platinum wire, one end of the latter being fastened to the inner end of the metallic
wire, and the other end soldered to the body of the priming screw plug, the said
electrical frictional priming screw plug having the bore, and friction wire, formed
or arranged in such a manner, that the piece of ordnance can be discharged either by
electricity or by hand, all substantially as and for the purposes herein described with
especial reference to Figure B of the accompanying drawings.
Dated this 17th day of October 1890.
Dateli
GITIS ITCH day of October rosu.
ALFRED LONGSDON.
By Brewer & Son,
33, Chancery Lane, London, Patent Agents.