Improvements in Detonators.
Year: 1894

page_text: Date of Application, 26th Jan., 1894
Complete Specification Left, 25th Oct., 1894-Accepted, 26th Jan., 1895
PROVISIONAL SPECIFICATION.
Improvements in Detonators.
I, FREDERICK JOHN SMITH of 28 Norham Gardens, Oxford, Clerk in Holy
Orders and Millard Lecturer in Mechanics, Trinity College, Oxford, do hereby
declare the nature of this invention to be as follows:-
The invention has for its object improvements in detonators whereby a cheap,
simple and effective means for detonating explosive charges such for instance as
gun cotton, nitro-glycerine, and other high explosives is obtained.
I have discovered that if a small quantity of gun cotton is placed in a con-
tainer surrounded by air or any suitable gas and the air or gas is suddenly compressed
sufficient heat is generated to cause detonation of the charge of gun cotton. This
principle I adopt in the construction of my improved detonator. In carrying my
invention into effect I may as the most simple form adopt a cylinder closed at one
end and fitted with a plunger; in the bottom of the cylinder I place a sufficient
quantity of gun cotton (which is very small) to communicate fire with the main
charge of high explosive. I place the cylinder partly within the said charge of high
explosive with the plunger rod projecting therefrom then by suddenly mechanically
forcing the plunger forward the air or gas in the cylinder is compressed and the
small charge of gun cotton detonated thereby which by shattering the cylinder
fires off the main charge.
Instead of moving the plunger forward mechanically I may place a small charge
of gunpowder behind the plunger and ignite it by heat obtained from a platinum
wire placed in an electric circuit or other means of firing the gunpowder may be
adopted, then by the compression of the gas or air in the cylinder, by the
explosion of the gunpowder forcing forward the plunger, the air is compressed
around the gun cotton and the latter detonated. It will be evident that the
detonator may be of any desired form and dimensions and it may be used in con-
nection with torpedoes and other missiles so that on striking an object the plunger
will be driven into the cylinder and thereby cause detonation.
When using a projecting plunger rod, a cross pin may be passed through it to
ensure safety or other convenient means may be adopted.
Doted Tonuar 26th 1904
Improvements in Detonators.
I, FREDERICK JOHN SMITH, of 28 Norham Gardens, Oxford, Clerk in Holy
Orders and Millard Lecturer in Mechanics, Trinity College, Oxford, 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 :-
The invention has for its object improvements in detonators whereby a cheap,

page_text: .
simple, and effective means for detonating explosive charges, such for instance, as
gun-cotton, nitro-glycerine, and other high explosives, is obtained.
I have discovered that if a small quantity of gun-cotton is placed in a container
surrounded by air or any suitable gas, and the air or gas is sufficiently quickly
compressed, sufficient heat is generated to cause detonation of the charge of
gun-cotton. This principle I adopt in the construction of my improved detonator.
In carrying my invention into effect I may, as the most simple form, adopt a
cylinder closed at one end and fitted with a plunger; in the cylinder place a
sufficient quantity of gun-cotton to fire the main charge of explosive.
I place the cylinder partly within the said charge of explosive with the plunger
rod projecting therefrom; then, by forcing the plunger forward sufficiently quickly,
the air or gas in the cylinder is compressed and the charge of gun-cotton contained
in the cylinder detonated thereby, which, by shattering, the cylinder fires off the
main charge. I either move the plunger forward mechanically, or I may place a
small charge of gunpowder or similarly acting body behind the plunger and ignite
it by heat obtained from a platinum or other wire or other substance such as a
carbon filament placed in an electric circuit, or other means of firing the gun-
powder may be adopted; then, by the compression of the gas or air in the cylinder,
by the explosion of the gunpowder forcing forward the piston or plunger, the air
is compressed around the gun-cotton and the latter detonated.
It will be evident that the detonator may be of various forms and dimensions,
and it may be used in connection with torpedoes and other missiles, so that on
striking an object the plunger will be driven into the cylinder and thereby cause
detonation or sudden combustion of the compound in the detonator.
When using a projecting plunger rod, a cross pin may be passed through it to
ensure safety, or other convenient means may be adopted.
My invention is represented in the accompanying diagrams, in which :-
Figure 1 is a section of one of my improved detonators in its simplest form.
Figure 2 represents a similar detonator fixed in the pointed or fore end of a
shell.
Figure 3 is a section of a detonator in which the plunger is moved forward by a
small explosive charge acting against the outer end thereof.
Figure 4 is a section of a detonator operated similarly to that shown at Figure 3,
but having an enlarged piston and cylinder connected respectively with the com-
pression plunger or piston and cylinder in order to obtain increased area for the
piston propelling charge to act against, and
Figure 5 is a section of a detonator in which the compression plunger or piston
is operated by compressed air operating against a larger piston than the compression
piston.
In all the figures like parts are indicated by similar letters of reference.
c is an air
a. a¹ represent a cylinder; the part a¹ receives a charge b of gun-cotton or other
like explosive which is safe to handle and may be made thinner or weaker than the
part a so that it may be the first part of the cylinder to give way.
space between the detonating charge b and the plunger or piston d, which latter
extends beyond the cylinder a to enable it to be mechanically operated to effect the
compression of the air in the space c and consequently the explosion of the
charge of the detonator. The cylinder a. al may be made of wood, vulcanite,
glass, metal, or other suitable material, or of a combination of any two or more"
thereof.
The detonator in its simplest forin, as shown at Figure 1, may be applied in
any convenient manner to an explosive charge or to a shell or chamber containing
an explosive charge, and it may be operated by any suitable mechanical means
acting to drive inwards the plunger or piston d.
The said detonator is shown applied, in Figure 2, to the pointed end of a shell,
in which case the projecting end of the plunger or piston d is protected against
being accidentally forced inwards, by a cross pin e passed therethrough as shown,
or by other suitable means.

page_text: In the modification shown at Figure 3 the plunger or piston d is completely
enclosed within the part a of the cylinder a a', and instead of being mechanically
forced forwards to compress the air and consequently explode the charge b, it has
at the outer end of it within the cylinder a, a charge of explosive compound,
which is retained in position by a screw plug g containing a platinum wire h or
other like known device which projects from said plug into the charge f, so that
on an electric current being passed through said wire, it will be heated and the
charge exploded, whereby the plunger or piston d is forced forwards and effects
the explosion of the charge bas before explained.
The detonator shown at Figure 4 is of similar character to that shown at
Figure 3, except that an enlarged chamber or cylinder a² is connected with the
cylinder a and a head or piston d' fitting the cylinder a² is attached to the piston d,
by which means a larger area is provided to receive the pressure of the gases
arising from the explosion of the charge f. a³ are vent holes in the cylinder a² to
give free vent to the air in front of the head or piston d' and thereby prevent
obstruction thereto.
The modified detonator shown at Figure 5 is constructed similarly to that shown
at Figure 4 except that the charge f and wire hare dispensed with and a screw
cap i is substituted for the screw plug g and a tube i¹ is attached to the cap i. In
this modification the piston d' is forced forward by compressed air conducted to
the cylinder a² by the tube i', and such compressed air may be supplied from any
suitable source.
The detonating charge 6 of gun-cotton or other like explosive which is safe to
handle in all cases, is placed in the cylinder a¹ in a loose form so that a large
surface is exposed to the heated air caused by the compression; it is necessary
that it should be thus placed to ensure instantaneous action.
In all cases of air or gas compression, in order that the greatest heating effect
may be produced, the compression should preferably be adiabatic, that is, it should
so take place that there be the least possible loss of heat through the walls of the
cylinders used nor through the piston.
In order that this may be effected in my improved detonators in case of com-
paratively slow compression I use a piston of non-conducting material, such as
hard wood or vulcanite; I also make the cylinder of a non-conducting material,
such as glass or hard vulcanite or vulcanized fibre which is strengthened by an
external cylinder of metal or by wire wound on to it.
The space c in the cylinder a. a' may be filled with air or other gas, oxygen
being the best to use, but air acts efficiently.
By the employment of detonators constructed as herein described, I avoid the
use of fulminates of mercury and silver and similar violent explosives, which are
subject to explode in handling and by such means obtain comparative safety in the
use of high explosives for mining and other purposes. The sizes and proportions
of the parts, of the detonator shewn in the drawings, which are made to the scale
shown at Figure 6, are approximately the sizes which act well but I do not confine
myself to these dimensions. I use generally 10 to 15 grains of explosive substance b
in each detonator. The driving charge ƒ in Fig. 3 and Fig. 4 is usually 7 grains.
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. The improved detonators for firing explosive charges, such as gun-cotton,
nitro-glycerine, and other explosive compounds, consisting of a cylinder con-
taining gun-cotton or other similar acting explosive which is safe to handle and
furnished with a piston or plunger, and having the space below the plunger
containing the gun-cotton or other explosive compound filled with air or gas, the
said piston or plunger being driven forward in order to effect the compression of
the said air or gas, substantially as herein shown and described and for the purpose
stated.

page_text: 2. The improved detonators constructed substantially as herein shown and
described and for the purpose stated.
Dated October 25th 1894.
By Harris & Mills,
F. J. SMITH,
23, Southampton Buildings, London, W.C., Agents.