A NOVEL METHOD OF SHOT FIRING AND BLASTING IN MINES,
Year: 1886

page_text: I FRANK BRAIN of the Trafalgar Collieries, Drybrook, Gloucestershire, Mining
Engineer & Colliery Manager do hereby declare the nature of my invention for
A NOVEL METHOD OF SHOT FIRING AND BLASTING IN MINES, BY THE AGENCY OF
ELECTRICITY to be as follows:-
My Invention comprises a novel method of utilising Electricity for the purpose
of firing explosive charges of all descriptions used for blasting purposes such for
instance as in the "getting" of coal, quarrying stone and the like: And, an
essential feature in and arising from the adoption of, my Invention, consists in
the firing of the explosive shot or charge being effected also with absolute
immunity from the risk of any inflammable gases which may be present in the
mine, becoming ignited and exploded.
-
With the last named object in view, I avoid the use of induction coils or so
called electro magnetic or magnetic exploders which ignite the explosive shot or
charge by sparks; and, in lieu thereof I adopt and employ a system of cables or
conductors comprising say a pair of "mains" well insulated and conveyed or led
from any convenient point where power is available, into the main ways or roads-
say of a coal mine-and, any desired number of branch cables (of lighter section
than the "mains"); these latter being also well insulated--are led off from the
"mains " to the "face of the coal headings or other points where blasting is
required. Sparkless, well protected switches are disposed at different convenient
parts of the circuit and are operated in the manner and for the purpose hereinafter
mentioned.
1
The ends of the branch cables-or "leads "-above referred to, are provided
and "bridged over "with a conductor of high resistance say, of metal, carbon; or,
of any suitable chemical substance which becomes incandescent, or even fuzed by
the Electric current which circulates when the switch aforesaid is " оп, and thus
fires the explosive charge or shot aforesaid.
.
"
A dynamo machine would be connected to the charging ends of the cable
"mains" aforesaid and a constant current of Electricity be caused to pass through
said "mains." Instead however of a dynamo machine, primary or secondary

page_text: batteries might be utilised for the purpose last mentioned and in the manner
hereinafter referred to..
"
The ordinary method of firing the shot or charge would be as follows:-Any
number of the explosive charges (each charge containing an Electric fuse) in a coal
face," '- or other heading where blasting may be required,-would be connected
together; and then this continuous line of shots or charges would be joined to the
nearest branch cables or "leads." When all is ready for firing, the operator would
unlock the box in which the switch is secured, and, turning the switch "on," the
current of electricity (which is continuously travelling through the "mains" as
aforesaid) would be caused to pass round the shots or charges and so to fire them
simultaneously.
In cases where primary or secondary batteries are adopted for the purpose
aforesaid, it may be found advantageous to fix the boxes containing the electric
energy upon cars or waggons such as are used in a coal mine. The battery or
batteries would then have attached thereto the requisite lengths of cables and the
cars or waggons aforesaid could then be taken to the different parts where the
firing is to take place. The method of firing would be the same as that herein-
before described.
The arrangement last above described would form a substitute for the cable
system of firing hereinbefore described, although the functions would be similar
and result in a perfectly sparkless ignition of the shot or charge.

page_text: A Novel Method of Shot Firing and Blasting in Mines by the
Agency of Electricity.
:
I FRANK BRAIN of the Trafalgar Collieries, Drybrook, Gloucestershire, Mining
Engineer and Colliery Manager, do hereby declare the nature of my invention for
A NOVEL METHOD OF SHOT FIRING AND BLASTING IN MINES BY THE AGENCY OF'
ELECTRICITY and in what manner the same is to be performed, to be particularly
described and ascertained in. and by the following statement :-
In accordance with my Invention I avoid the use of induction coils or so called
magneto-electric or magnetic exploders which ignite the explosive shot or charge
by sparks; and I substitute in lieu thereof the following means in order to ensure
that the firing of the explosive charge, shot, or cartridge, may be effected with
absolute immunity from the risk of any inflammable gases which may be present in
the workings of the mine becoming ignited and exploded.
In carrying out my Invention, I adopt and employ a system of cables or
conductors, comprising say a pair of "mains" well insulated and conveyed or led
from any convenient point where power is available into the main ways or roads of
say a coal mine-Any desired number of branch cables or "leads" of lighter con-
struction than the mains, and also well insulated are led off from the "mains
the face of the coal headings where blasting is required.
"
to.
Sparkless, well protected switches A are provided at different convenient parts
of the electrical circuit and are operated in the manner and for the purpose
hereinafter mentioned.
I have shewn in the detailed view Figure 2 a diagram illustrative of the type of
non-sparking switches which I prefer to adopt with a view to ensure absolute
security from the risk herein before referred to arising from the firing of explosives
in mines or other subterraneous places-That is to say, one in which contact is
made below the surface of a non-conducting liquid.
.
A dynamo machine would be connected to the charging ends of the cable
"mains" aforesaid; or, instead of a dynamo machine, primary or secondary batteries
might be utilised to generate the electric current.
The ends of the branch cables or "leads" aforesaid are "bridged over" at a with
a conductor of high resistance, say of metal, carbon; or of any suitable chemical
substance which becomes incandescent or even fused by the electric current and
thus fires the explosive shots, charges or cartridges b aforesaid inserted in the blast
holes.
The method of firing the explosive shot, charge or cartridge b would, in the
ordinary course be as follows-
on
"
Any number of the latter would be connected together as shewn in the drawing
as at c and d; and then, this continuous line of shots would be joined to the
nearest branch cables or "leads "-When all is ready for firing the operator would
unlock the box at A in which the switch is secured; and, turning the switch"
the current of electricity which is constantly passing along the "mains would
be caused to travel round the shots, charges or cartridges, and so to fire them
simultaneously.
13

page_text: "
I may either adopt the system of "series" firing as shewn to the left of Figure 1,
or the "parallel arc system shewn to the right hand thereof; or, if deemed
advisable I may under certain conditions use a combination of "series" and
"parallel arc circuits.
"
I wish it to be understood that when the shots or cartridges are arranged in
"series" that the substance within the explosive compound which is to be heated
by the electric current has a sufficiently low resistance as to render it proportional
to the maximum electro-motive force of the generating dynamo (or of the battery
or batteries) Whilst on the other hand, when the "parallel arc" system of firing
is adopted then the electrical generator would have to be so constructed as to give
a large current with a comparatively low electro-motive force.-Hence it will be
apparent the number and arrangement of the fuses must correspond with or be in
proportion to the capacity of the electrical generator, or vice versa.
In cases where primary or secondary batteries are adopted for the purposes
herein specified, it may be found advantageous to fix the boxes containing the
electric energy upon cars or waggons such as are used in a coal mine.-The battery
or batteries would then have attached thereto the requisite lengths of cables, and
the cars or waggons could then be taken to the different parts where the firing is
to take place. The method of firing would be the same as that herein before
described. This arrangement as last described would form a substitute for the
cable system of firing hereinbefore set forth, although the functions would be
similar, and result in a perfectly sparkless ignition of the shot, charge or cartridge.
In the case of surface firing the current will not be continually flowing through
the cables; but all the connections in the pit will be made first, then the miners at
br ches where firing will be required will put the "leads" into connection with
ains" through the switches of the respective circuits and will leave the
mi When all the employés have withdrawn from the workings, the circuit on
the surface will be completed through the dynamo or batteries and the charges'
below are simultaneously exploded.
.
i
"
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
First For the purposes of shot firing and blasting in mines and the like by the
agency of Electricity, the use of the system of insulated "mains" and branch cables
or "leads" with accessory parts substantially as herein set forth.
Second-The non-sparking switches herein. described, operated in the manner
and for the purposes all substantially as herein set forth.