IMPROVEMENTS IN ORDNANCE
Year: 1871

page_text: LETTERS PATENT to Sir Joseph Whitworth, Baronet, of Manchester,
in the County of Lancaster, for the Invention of “IMPROVEMENTS IN
ORDNANCE."
Sealed the 24th October 1871, and dated the 15th August 1871.
COMPLETE SPECIFICATION filed by the said Sir Joseph Whitworth at.
the Office of the Commissioners of Patents, with his Petition and
Declaration, on the 15th August 1871, pursuant to the 9th Section.
of the Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, Sir
JOSEPH WHITWORTH, Baronet, of Manchester, in the County of Lan-
caster, send greeting.
WHEREAS I am in possession of an Invention for "IMPROVEMENTS.
IN ORDNANCE," and have petitioned Her most Excellent Majesty Queen
› Victoria to grant unto me, my executors, administrators, and assigns,
Her Royal Letters Patent for the same, and have made solemn.
Declaration that I am the first and true Inventor thereof.

page_text: NOW KNOW YE, that I, the said Sir Joseph Whitworth, do hereby
declare the nature of the said Invention to be as follows:-
-
This Invention has for its object improvements in ordnance.
In constructing breech-loading cannon I employ to close the breech
a sliding block working between two portions of the breech end of the
gun under and over the sliding block, which I call block guides. The
faces of the block guides are grooved with a number of parallel grooves,
and the upper and lower surfaces of the block are similarly formed.
The grooves in the block guides are nearly but not quite perpendicular
to the bore, so that when the block is moved along the block guides
into the position where it closes the breech it is drawn up to the
breech face by the grooves, which for convenience I may call a
straight line screw. The threads of the screw are angular, both
sides of the threads on the block guides are inclined towards the
muzzle, their sides nearest to the muzzle being undercut, so that when
the heavy strain resulting from firing the charge comes upon the block
there may be no tendency to force the block guides apart, but on the
contrary they are tightly held so that they cannot separate; where, as is
usual, the breech of the barrel tube is hooped the block guides are
formed by cutting away the sides of the projecting end of the hoop.
Instead of a straight line screw, which I prefer, the screw may be formed
of moderate curvature without departing from the principle of my
Invention. The above construction allows of the strain resulting from
the discharge of the gun, and tending to force out the breech block,
being distributed over so large an area of resisting surface on the faces
of the screw threads that there is no risk of the metal being locally
overstrained, and by closing the breech by a single massive sliding
block moving along screw threads as above great simplicity and solidity
are attained. I recommend the powder chamber of the gun to be made
considerably larger in diameter than the bore, so large that although the
powder charge be much heavier than is usual its length may be only
about two calibres. The shortness of the powder chamber facilitates
the loading, and the gun can consequently be more rapidly served, and
what is of more importance the powder is better consumed. The vent
is at the top. The sliding breech block is shaped at the side so as to
form a tube or part of a tube of the same diameter as the powder
chamber, and when the breech is open this tube or part of a tube forms
a prolongation of the chamber. It is desirable to fit an inner guide

page_text: corresponding with the bore of the piccc and similarly rifled into this
tubular part, and through this rifled shot guide the projectile is inserted
into the bore, and its length enables it to enter the bore before it passes.
clear of the guide. This shot guide is removed before the powder
cartridge is inserted. The guide on the block leads the cartridge truly
into the chamber of the gun. The breech block is worked by means of
a rack and pinion. A stud is formed on or fixed in the back of the breech
block, and a weighted hand lever is mounted upon it. On the same stud
a pinion is mounted, and it gears with a rack fixed upon the lower guide
of the breech block. The pinion is worked by the hand lever, the handle.
and pinion having interlocking projections, allowing, however, the handle
some freedom of motion, so that it may be used with a hammer-like.
action to start the breech block. A pawl on the block prevents the
Figure 1 is a plan, Figure 2 a vertical section, and Figure 3 a hori-,
zontal section of a field piece constructed according to my Invention,
Figure 4 is a view of the breech end with the breech closed, and Figure 5
is a similar view with the breech open.
a, a, is the main tube or barrel of the cannon, and 6 is the breech
hoop, which in the case represented by the Drawing carries the trunnions.
In guns of a larger size additional hoops may be used to obtain greater
strength. 6¹, b', are the guides for the breech block. They are formed by
cutting away the sides of the breech hoop where it projects beyond the
3 breech face a* at the end of the barrel or tube a; c is the breech block
with the straight line screw upon it interlocking with the corresponding
internal straight line screw on the block guides 6'. This screw is shewn
to a larger scale at Figure 6. The dimensions of the thread are such
as they should be for a bolt of a diameter equal to the distance between
the block guides, and it will be seen that the sides of the threads are
inclined inwards, so that the recoil of the breech block has no tendency
to separate the guides, as it would have if an ordinary V form thread
were employed. The incline of the screw thread to the axis of the gun
is about three degrees; c' is a stud projecting from the back of the
breech block, and da pinion upon it gearing with a rack e on the block
guide '; f is a weighted lever handle on the same stud and held
thereon by the nut c*. The interlocking projections on the pinion d

page_text: and lever handlef are marked d* and f*. As already stated they allow
the lever to be used with a hammer-like action to turn the pinion;
c³ is a pawl on the breech block, which by taking into a notch d¹ in tho
pinion prevents it running off the rack e except when the pawl is
intentionally lifted; g is the vent entering the top of the enlarged
powder chamber a¹; a' is a steel packing ring known as the gas check;
a³ is the part of the bore into which the projectile is introduced in
loading; it is very slightly larger than the remainder of the bore in order
that the projectile may enter it easily; o³ is the cartridge guide formed
on the breech block. In the case represented in the Drawing it is
somewhat more than a semi-cylinder, but it may be a complete tube;
h is the shot guide, it is held within the cartridge guide, as is seen at,
Figure 5, and is shewn separately at Figure 7.. In loading the pro-:
jectile is inserted through this guide, and is led by it into the part a³
of the bore, the parallel part of the projectile being long enough for
the projectile to enter accurately into the bore before it leaves the guide.
The projectile having been inserted, the guide h is removed to leave a
clear passage for the cartridge, and the breech is then closed; is part
of the link by which the gun is elevated.
Having thus described the nature of my said Invention, and the
manner of performing the same, I would have it understood that I do
not confine myself to the exact details, but I claim the arrangement for
closing the breech of ordnance by a breech block moved along and held
by grooves, the direction of which is inclined to the breech face of the
gun, substantially as described..
.
the
I also claim the method substantially as described of forming
screw thread, so that the force of the explosion on the breech block may
not tend to separate the guides, but rather to draw them together.
;
In witness whereof, I, the said Sir Joseph Whitworth, have here-
unto set my hand and scal, this Eighth day of. August, in the:
year of our Lord One thousand eight hundred and seventy-one.