IMPROVE- MENTS IN ORDNANCE, AND OTHER FIRE-ARMS, AND IN TOOLS FOR RIFLING THE SAME
Year: 1862

page_text: PROVISIONAL SPECIFICATION left by. Perceval Moses Parsons at the
Office of the Commissioners of Patents, with his Petition, on the 16th.
May 1862.
I, PERCEVAL MOSES PARSONS, of Blackheath, in the County of Kent, Civit
Engineer, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN ORDNANCE, AND OTHER FIRE-ARMS, AND IN TOOLS FOR RIFLING THE SAME,"
to be as follows:-
My Invention consists, firstly, of a method of constructing cannon, so as to
enable them to resist the increased strain due to rifling, the use of elongated
projectiles, and heavy charges of powder. For this purpose, I form the main
portion of the gun of cast iron, but instead of casting it solid, or with a solid
breech, as usual, I cast it with the bore right through; and I employ a hollow"
pipe, encased in loam, or other suitable substance; to form. the core; through-
which a stream of water is made to flow while the gun is being cast, and
during the time it is cooling. I then bore out a conical recess at the breech"
end of the gun, larger in diameter than the intended finished size of the bore,"
but extending only a portion of its length, and I fit into the recess, a tube of
wrought iron, steel, homogeneous metal, or other suitable material, accurately
turned to the shape and size of the conical recess, which I force in and secure"
by a breech plug screwed into the breech of the gun in the case of muzzle--
loading guns, or by a nut or hollow screw in the case of breech-loaders. The
tube may be in one piece of metal, or built up of several, either by fitting two-
or more rings together, or by shrinking or forcing one or more tubes, or rings;

page_text: on to an inner tube or tubes. I also apply the conical tube in the manner
herein-before described, to guns cast solid, or with an ordinary or solid metal
core, as well as to guns already made for the purpose of strengthening them,
and in some cases I apply the conical tube in combination with a tube of
wrought iron, steel, homogeneous metal, or other similar material, with which
the gun is lined throughout the whole length of the bore.
My Invention, secondly, consists of a peculiar form of rifling, which is
adapted to any kind of fire-arms, but is particularly suited to ordnance, as it
enables hard metal projectiles to be used, which do not require to be machine-
shaped, or made with greater accuracy than can ordinarily be obtained by
casting, either in sand or metal moulds, and which, notwithstanding any
variations in the size of the projectiles, will always ensure a large bearing
surface to act on and impart to it the rotatory motion, and will always cause it
to be truly centred with the axis of the bore of the gun. To effect these
objects, the figure in cross section, of the grooves, or of that portion of the
grooves which constitutes the driving side, is described by arcs of circles, the
centres of which are placed in a circle (which I term the generating circle),
struck from the centre of the bore, at equidistant points around it, and so that
a straight line, drawn from a point taken somewhere on each arc, (and which
point, to obtain the full advantage of the system, should be equidistant from
its two extremities), to the centre from which it is struck, will be at right
angles to a line drawn from it to the centre of the bore. The diameter of this
generating circle will vary according to the number and depth of the grooves,.
but it should always be less than that of the bore..
My improvements in the tools for rifling, consist of a method of constructing
actuating, and securing the cutters in the rifling mandril, so as to produce
grooves of the form herein-before described; as well as grooves of other forms,
and so constructing the rifling mandril, as to cause a decrease of depth of the
grooves in certain parts of the barrel when required. For this purpose, for
rifling guns.of large size, in which it would be difficult to take a cut of the
whole width of the groove, I employ one or more cutters or frames carrying
them, which are mounted on pivots or centres in the rifling 'mandril, corre-
sponding to the centres in the generating circle, and the cutters or the frames
carrying them are made to turn on their centres or pivots by means of wedges
or screws, and are thereby set up, so as to take a fresh cut at each successive
stroke of the rifling mandril. In the case of small guns, and small arms, in
which a cut can be conveniently taken the whole width of the groove, the
cutting tool is made of a bar of steel, of any suitable form; this is carefully
fitted into a slot made in the rifling mandril; its rear end abuts against one

page_text: end of the slot, and rests on the bottom, and its front or cutting end rests
upon a set screw, having a fine thread tapped into the mandril, and by which
it is set up to take a fresh cut as required. Another small screw passes
through the mandril, and is tapped into the cutter, by which it is held down
and kept steady. When it is required to produce grooves of any form, com-
posed of arcs of circles, the front or cutting part of the cutting tool is turned
in a lathe, hardened and polished, the centres upon which it is turned being
adjusted according to the particular form of grooves required; if it is desired
to make them of the form herein-before described, the centres are made to
correspond to the centres on the generating circle; but if grooves of the form
of a single are of a circle are desired, the front of the tool should be turned
to a plain cylinder. The slot in the mandril is made longer than the cutter,
so as to form a small chamber in front of the cutting edge, to allow the
shavings to collect. The cutter is sharpened by grinding its front end to a
suitable angle. For the purpose of causing the grooves to decrease in depth,
slightly, either at the breech or the muzzle, I form that portion of the rifling
mandril, for a short distance on each side of the cutting edge of the cutter, of
a slightly less diameter than the other portions, by which, when in the process
of rifling, the mandril arrives at either end of the barrel, and is partly sup-
ported by that portion which is of reduced diameter, the cutter will recede
slightly, and thereby cut the grooves at that part of rather less depth than in
the rest of the barrel, by which a slight contraction at either or both ends of
the barrel may be obtained as required.