Year: 1887

page_text: Date of Application, 17th Dec., 1887
Complete Specification Left, 5th Sept., 1888
Complete Specification Accepted, 12th Oct., 1888
I, 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:-
Electrical primers such as are carried at the centre of the base of cartridges for
breech loading guns are for the most part made with a central metallic stem protruding
through a hole in the centre of the base of the outer metallic casing and insulated
from it, whilst within the case there is a fine platinum wire passing from the inner
end of the stem to the casing this wire becomes heated on the passage of an electric
current through it and fires the explosive material by which the wire is surrounded.
With such primers there is always more or less liability of the wire when heated
failing to fire the explosive material in the primer and miss fires in some cases arise
from this cause. Either the fine wire has been broken at the time when gun cotton
or like material was being wrapped around it or else the gun cotton or material has
not been brought into contact with the wire so that the wire might even be fuzed
without firing the charge.
To remedy this I provide two or more fine wires passing from the central steni to
the outer casing and surround each wire with explosive material so that even if one
fine wire failed to ignite the charge the ignition would be effected by the other or
others.
Electrical primers or fuses of this construction may be used not only for igniting
cartridges in breech loading guns but also for igniting charges of explosive for other
purposes.

page_text: I, 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 and in what manner the same is to be performed to be particularly described
and ascertained in and by the following statement :-
· Electrical primers such as are carried at the centre of the base of cartridges for
breech loading guns are for the most part made with a central metallic stem protruding
through a hole in the centre of the base of the outer metallic casing and insulated
from it, whilst within the case there is a fine platinum wire passing from the inner
end of the stem to the casing this wire becomes heated on the passage of an electric
current through it and fires the explosive material by which the wire is surrounded.
With such primers there is always more or less liability of the wire when heated
failing to fire the explosive material in the primer and miss fires in some cases arise
from this cause. Either the fine wire has been broken at the time when gun cotton
or like material was being wrapped around it or else the gun cotton or material has
not been brought into contact with the wire so that the wire might even be fused
without firing the charge.
To remedy this I provide two or more fine wires passing from the central stem to
the outer casing and surround each wire with explosive material so that even if one
fine wire failed to ignite the charge the ignition would be effected by the other or
others.
Electrical primers or fuses of this construction may be used not only for igniting
cartridges in breech loading guns but also for igniting charges of explosive for other
purposes.
Figure 1 of the drawing annexed is a longitudinal section of a cartridge case fitted
with an electrical primer or fuse formed as above described-and Figure 2 is a front
end view of the same.
A is the base of the cartridge case-B the outer metallic casing of the primer or
fuse screwed into it-C is the central metallic stem insulated from the outer case B and
DD are two or it might be a greater number of thin platinum wires passing from the
stem to the edge of the outer metallic case B. These wires are to be surrounded with
gun cotton or like material in the same way as the single wire heretofore used.
Having now particularly described and ascertained the nature of iny said invention
and in what manner the same is to be performed, I declare that what I claim is
-
1. An electrical primer or fuse formed of a cylindrical casing. a metallic stem
passing centrally through and insulated from it and two or more thin metallic wires
passing from the inner end of the central stem to the cylindrical casing and
surrounded by gun cotton or like material ignitable by heat.
2. The construction of electrical primers or fuses substantially as herein before
described and illustrated in the drawing annexed.
Dated this Bib day of August 1888