Year: 1888

page_text: 1, WILLIAM SPEIRS SIMPSON, of 49, Battersea Park Road, Surrey, Engineer do
hereby declare the nature of this invention to be as follows :—
This invention relates to an improvement in or connected with Firearms and
Ordnance, the object being to obtain increased velocity and better combustion of
powder.
For the purpose of my invention, I apply or affix a tubo of somewhat larger
diameter than the barrel of a gun on to the nozzle end and this tubo at or near its
outer portion is provided with a disc or diaphragm of metal which confines the air
within the barrel and tube while the shot is travelling along after the charge is fired
until a pressure sufficient is produced to burst the diaphragm and allow the shot to
leave!
am is affixed to the tuba by. screw or otherwise.
H. GARDNER,
166, Fleet Street, London,
Agent for the said William Speirs Simpson.

page_text: An Improvement in or Connected with Fire-arms and Ordnance.
I, WILLIAM SPEIRS SIMPSON of 49 Battersea Park Road, Surrey, Engineer,
do hereby declare the nature of my said invention 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 an improvement in or connected with Fire Arms and
Ordnance, the object being to, obtain increased velocity, and better combustion of
powder.
For the purpose of my invention I apply or affix a tube of somewhat larger
diameter than the barrel of a gun on to the muzzle end and this tube at or near its
outer portion is provided with a disc or diaphragm of metal which confines the air
within the barrel and tube while the shot is travelling along after the charge is fired
until a pressure sufficient is produced to burst the diaphragm and allow the shot to
leave.
The disc or diaphragm is affixed to the tube by screw, or otherwise.
The annexed drawings show an example of my invention.
Figure 1 is a part sectional elevation of a small arm or rifle barrel with the tube
and disc or diaphragm affixed.
Figure 2 is a part sectional elevation of a cannon barrel with tube and disc
affixed.
A is the ordinary barrel of a Rifle. B the tube fitted on the muzzle by a Bayonet
joint over and behind the fore-sight C, said tube being of larger diameter than that
of the barrel A and forming an air chamber closed by the disc. D this being held
tightly in place by the screw capping or collar E.
The disc D has an annular groove on one side or it may be on both sides as at
Figure 3 so as to leave a very thin. portion of metal at the bottom of the grooves,
said portion of metal being in every case sufficient to withstand the internal pressure
of air caused by the travel of the bullet or shot along for the full length of the
barrel, the bullet or shot being gradually retarded in its travel in proportion to the
increasing compression of the air in front of it which retardation permits of the full
expansion of the gases produced from the ignition of the charge and the development
of force for the propulsion of the bullet or shot.
So soon as the internal air pressure exceeds the strength of the thinnest part or
groove of the disc or diaphragm D the centre portion of it is blown out the shot
being free for flight.
This system of confining the air within the muzzle of a fire arm or a cannon is
very advantageous for long range shooting with long shot because of the increased
initial volocity given to the bullet and the very low trajectory it assumes compared to
the distance travelled.
At figure 4 I show a diagram of the trajectory or flight course of a bullet from an
ordinary rifle for 1,000 yards range when fired without the disc and the trajectory or
curve of a bullet for the same distance when fired from the same rifle with the tube
and disc affixed.

page_text: I purpose making my grooved discs or diaphragms of some ductile metal, such as
copper or brass but any metal or alloy or substance having the necessary strength
and quality of clean fracture will answer the purpose.
Having now particularly 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. The employment of grooved discs or diaphragms in air chambers at the muzzle
ends of fire arms, Field Guns and Cannon, as and for the purpose or purposes set
forth.
2. In combination with grooved resistance disc D, the tube B and collar E and
constituting an appliance or apparatus attachable to a gun for the purposes set
forth.
3. The annular grooved disc or diaphragm D affixable to and closing up the muzzle
end of a gun and in a chamber of larger diameter than that of the guns bore as and
for the purpose or purposes described.
day of Coruary 10OJ.
H. GARDNER,
166, Fleet Street, London,
Agent for the said W. S. Simpson.