Improved Apparatus for Measuring the Pressures of Powder Gases at Various Points in the Lengths of Gun Barrels.
Year: 1897

page_text: Date of Application (in United Kingdom), 24th May, 1897
Complete Specification Left, 18th Sept., 1897-Accepted, 6th Nov., 1897
PROVISIONAL SPECIFICATION.
Improved Apparatus for Measuring the Pressures of Powder Gases at
Various Points in the Lengths of Gun Barrels.
I, JULES POLAIN, Director of the Proving Butt for Fire-arms, Liège in the
Kingdom of Belgium, do hereby declare the nature of this invention to be as
follows:-
The apparatus forming the subject of this invention serves, firstly, to determine
the pressures of the powder gases throughout the whole length of a gun barrel
whatever may be its calibre, and, secondly, to determine from those pressures,
what should be the thickness of the barrel to resist the bursting action of any
given powder.
The apparatus consists of the following devices: A gun barrel has a series of
holes bored through the sides thereof at right angles to the axis. These holes
are placed at various points along the length of the barrel, which is wholly or partly
enclosed in a steel or other suitable sleeve or casing. Through this sleeve are
bored holes the axes of which are in line with those of the holes bored through
the gun barrel. These holes in the sleeve are tapped with screw threads, and
into them are screwed plugs through which are bored holes the centres of which
are in line with the axes of the holes in the gun barrel; the outer parts of the
holes through these plugs are tapped to receive set screws, and the inner parts
of the said holes are made of the same size and exactly in line with the holes in
the gun barrel. In each of the holes in the gun barrel and the prolongation thereof
formed by the hole at the inner part of the plug is placed a piston or plunger,
and between the head of each piston or plunger and the end of the corresponding
set screw is placed, and held in position by the said set screw, a crusher cylinder
of copper which is placed in position exactly over the centre of the head of the
piston through a suitable guide tube, and is then held there by the said set screw
being screwed down upon it. The cartridge case containing the powder to be
experimented with may be of copper, card board, or other suitable material and
should be provided with lateral openings corresponding to those of the holes
through the sides of the barrel, fitted with crusher pistons, that may occur in the
length of the chamber into which the cartridge is inserted.
It will now be understood that when the crusher cylinders are put in place on
the heads of the pistons and secured in position by the set screws, the cartridge
containing the powder to be experimented with placed in proper position in the

page_text: ..
chamber of the barrel, and the breech closed, the apparatus is ready for a pressure-
measuring operation. On firing the cartridge, preferably by central fire, the gases
generated exert pressure on the aforesaid pistons, and these in their turn exert a
more or less crushing effect upon the crusher cylinders: The pressures. can be
determined from these crushing effects by the aid of a table of pressures properly
calculated with due regard to the calibre of the barrel, the sizes of the pistons,
and so forth, in a manner well understood in connection with pressure-measuring
apparatus in which the pressures are indicated by the crushing more or less of
crusher cylinders.
In order to prevent loss of some of the grains of powder through the above-
mentioned lateral holes or openings in the cartridge case, such holes or openings
may be covered with pieces of thin skin or other suitable material which is easily
broken through by the explosion of the powder.
1..
Dated this 22nd day of May 1897
t.
Per W. H. Beck,
J. POLAIN,
115 Cannon Street, London, E.C., Agent.
COMPLETE SPECIFICATION.
Improved Apparatus for Measuring the Pressures of Powder Gases at
Various Points in the Lengths of Gun Barrels.
I, JULES POLAIN, Engineer and Lawyer, and Director of the Proying Butt for
Fire-arms, Liège, in the Kingdom of Belgium, 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 apparatus forming the subject of this invention serves, firstly, to determine
the pressures of the powder gases throughout the whole length of a gun barrel
whatever may be its calibre, and, secondly, to determine from those pressures,
what should be the thickness of the barrel to resist the bursting action of any
given powder.
And in order that the invention may be fully understood I will proceed to
describe the same with the aid of the accompanying sheet of Drawings, in which
Figure 1 represents a longitudinal sectional elevation of the apparatus, Figure 2
a plan, and Figure 3 a partial back elevatica of same.
'
The apparatus consists of the following devices: A gun barrel A has a series
of holes, P, P, P²-PB bored through the side thereof at right angles to the
axis. These holes are placed at various points along the length of the barrel,
which is wholly or partly enclosed in a steel or other suitable sleeve or casing A*.
Through this sleeve or casing are bored holes Q, Q-Q the axes of which are
in line with those of the aforesaid holes bored through the gun barrel A. These
holes in the sleeve are tapped with screw threads, and into them are screwed plugs,
such as those marked B1 and B2, in Figure 1, through which are bored holes the
centres of which are in line with the axis of the holes P, P-P13 in the gun
barrel; the outer parts of the holes through these plugs are tapped to receive set
screws D1 D2 and the inner parts of the said holes are made of the same size, and
exactly in line with the holes P, P-P13 in the gun barrel. In each of the holes
in the gun barrel and the prolongation thereof formed by the hole at the inner
part of the plug is placed a piston or plunger, (such as those shown at C¹; C²)
which is called a crusher piston or plunger, the diameter and height of which
varies according to the calibre of the arm operated upon. Between the head of
each piston or plunger C and the end of the corresponding set screw ]) is placed,
and held in position by the said set screw, a' copper cylinder K which is placed
in position exactly over the centre of the 'head of the piston by means of a suitable

page_text: guide tube, or funnel, and is then held there by the said set screw being screwed down
upon it. The cartridge case (not shown in the Drawings) containing the powder
to be experimented with may be of copper, card-board, or other suitable material,
and should be provided with lateral openings corresponding to those of the
holes P, P, through the side of the barrel, fitted with crusher pistons, that may
occur in the length of the chamber E into which the cartridge is inserted.
It will now be understood that when the copper cylinders K are put in place on
the heads of the pistons C¹ C3 etcetera and secured in position by the set
screws D1, D2, the cartridge containing the powder to be experimented with placed
in proper position in the chamber of the barrel, and the breech closed by means
of the breech piece F held in place by the wing nuts G screwed on to studs H
secured in the rear end of the sleeve or casing A*, the apparatus is ready for a
pressure-measuring operation. On firing the cartridge, preferably by a central
fire striker such as that shown at I in Figure 1 for example, the gases generated
exert pressure on the aforesaid piston CC etcetera and these in their turn exert
a more or less crushing effect upon the copper cylinders placed between the
pistons C and the set screws D D. The pressures at various points in the length
of the barrel A. can be determined from these crushing effects by the aid of a table
of pressures properly calculated with due regard to the calibre of the barrel, the
sizes of the pistons, and so forth, in a manner well understood in connection with
pressure measuring apparatus in which the pressures are indicated by the crushing
more or less of copper cylinders.
In order to prevent loss of some of the grains of powder through the above-
mentioned holes or openings in the cartridge case, such holes or openings may be
covered with pieces of thin skin or other suitable material capable of retaining the
powder in the carriage case until broken through by the explosion of the powder.
In the Drawings only two of the plugs, set screws, and pistons are shown in
place, but it will of course be understood that each of the holes Q, Q-Q and
P, PP3 is to be provided with similar parts.
Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed, I declare that what I
claim is
First. Apparatus for measuring the pressure of powder gases at various points
in the lengths of gun barrels, which consists of a gun barrel having a series of
holes bored through the side thereof at right angles to the axis, a sleeve or casing
wholly or partially enclosing the said gun barrel and having a series of holes
formed therethrough the axes of which are in line with the axes of the holes in
the gun barrel, and a device applied to each of the said holes in the sleeve or
casing and gun barrel adapted to hold a copper cylinder in place, on the head
of a piston or plunger subjected to the pressure of the powder gases, substantially
as described.
Second. In an apparatus of the kind herein described the device applied to each
of the holes in the sleeve or casing and gun barrel, for holding the copper cylinder
in position and for transmitting the pressure of the powder gases to the said
copper cylinder, which consists of a perforated plug, a set screw, and a piston or
plunger, combined and adapted, substantially as described.
Dated this 17th day of September 1897