Improvements in Breech-loading Ordnance or Cannon.
Year: 1888

page_text: Improvements in Breech-loading Ordnance or Cannon.
I, WILLIAM THOMAS SMITH, a citizen of the United States of America, residing
at Birmingham in the county of Jefferson, in the State of Alabama, United States
of America, gentleman, do hereby declare the nature of my invention for IMPROVE-
MENTS IN BREECH-LOADING ORDNANCE OR CANNON and in what manner the same is
to be performed to be particularly described and ascertained in and by the following
statement.
The object of this invention is to provide a breech-loading cannon which can be
loaded with great rapidity and facility; and in which the joints at the breech can be
closed gas-tight.
Figure of the accompanying drawings is a longitudinal section through the
breech of this improved breech-loading cannon, showing the breech-block in position
to be locked against its seat at the rear of the bore and the loading device in position
for loading when the breech is open. Figure 2 is an end elevation of this improved
breech-loading cannon with the cap for covering the face of the breech removed.
Figure 3 is an end elevation of the breech with the cap or cover in position thereon.
Figure 4 is a transverse section through the body of the gun on a line passing
through the breech-block chamber. Figure 5 is a section taken longitudinally through
a portion of the gun at one side of its axis, the section line passing through the
breech block chamber and through the center of the breech-block therein. Figure 6
is an enlarged section showing a portion of the body of the gun, of the breech-block,
of the tubular breech-screw and the tubular calking thimble, and a section of the
gas-check rings. Figure 7 is an enlarged perspective view of a portion of the inner
end of the calking and packing thimble. Figure 8 shows a fragment of the breech-
block at the inner end of the breech-block chamber. Figure 9 is an enlarged vertical
section of the breech-block shoe in position in the breech-block. Figure 10 is an

page_text: enlarged plan of the underside of the breech-block-shoc. Figure 11 is an enlarged.
view of the abutting screws or stops at the inner periphery of the breech-block and
the inner end of the breech-block chamber. Figure 12 is an elevation of the front
face of the breech-block. Figure 13 is a diametrical section of the breech-block near
its front face. Figure 14 is a peripheral elevation of the breech-block at its outer
side. Figure 15 is a rear elevation of the breech-block. Figure 16 is an enlarged
perspective of the split thimble for closing the space around the actuating rod of the
breech-block. Figure 17 is a side elevation of the soft metal ring within said closing
device. Figure 18 is an edge view of said ring. Figure 19 is an enlarged sectional
view showing a fragment of the breech-block against its seat in the rear of the bore,
and the automatic gas-check embodied in said block. Figure 20 is a perspective view
of the tubular breech-screw with the arms supporting the rack broken off. Figure 21
is a perspective view of the calking or packing thimble. Figure 22 is an axial section
through the rear portion of the bore and through the breech-chamber, showing the
means for grinding the joints of the breech-block. Figure 23 is an end view of the
loading device. Figure 24 is an enlarged section of the breech-block in position
opposite the bore showing the automatic gas-check at its rear and front faces.
Similar numerals of reference indicate corresponding parts in the different
figures.
This breech-loading gun is constructed in any suitable manner, either cast or
built-up and is composed of iron, steel, or bronze, or a combination of such
metals.
The body 30 of the gun is provided in rear of the bore 31 with a breech-chamber 32
of larger diameter than the bore, and opposite the inner end of the breech-chamber
with a lateral slot forming a breech-block chamber 33 into which the breech-block 34
slides when the breech is opened. In built-up guns this slot is preferably cut before
the last two bands or rings are shrunk on.
The annular shoulder at the rear end of the bore and inner end of the breech-
chamber constitutes a seat 35 against which the breech-block rests when closed. This
seat is preferably faced with a ring of brass, gun-metal, or other suitable metal softer
than steel and of about the hardness of brass. The inner surface of the ring is
continuous with the surface of the bore. The front face of the breech-block is
ground against its seat to form a tight joint when the breech-block is closed.
The breech-block chamber 33 is recessed on its opposite sides forming ribs 36, which
serve as rests or guides for the breech-block when it is moved into and out of position
to be locked. The breech-block is provided with a circumferential rib 37, which holds
the body of the block out of contact with the top and ends of the breech-block
chamber and it is provided on its bottom with a flat-faced shoe 38 which slides on the
bottom of the breech-block chamber. This shoe is tapered at its opposite ends forming
wedge-shaped points which serve to push aside from its path any particles of dust that
may be within the breech-block chamber. The breech-block chamber is provided at
opposite ends of the path of the shoe with depressions or cellars 39 for receiving any
foreign matter that may be in front of the shoe. The breech-block is provided with
an oil-duct 40 which passes from the recessed rear end of the block through the body
thereof and through the shoe, for the admission of oil for lubrication. The shoe is
dove-tailed into the body of the block and is preferably composed of soft metal.
The inner end of the breech-block chamber is provided with a stop-screw 41 and the
inner periphery of the breech-block is provided with a corresponding screw 42 which
abuts against the screw 41 when the breech-block is pushed inward into position
opposite the bore. These abutting screws are preferably case-hardened, and their
ends are in the form of truncated cones, their conical portions projecting beyond the
face of the chamber and block respectively.
An actuating rod 43 for moving the breech-block extends through a hole in the
body of the gun at the outer end of the breech-block chamber and the inner end of
said rod is screwed into a socket in the breech-block, a check-nut 44 being fitted at
the upper end of said socket. This red is provided at its outer end with a handle 45
which is preferably hinged to the rod so as to fold against the side of the gun. The

page_text: space around the rod may be closed by a conical split thimble 46, having an external
screw-thread which takes into a screw-thread at the outer end of the hole for the
actuating rod. This thimble on being turned inward closes tightly around the
actuating rod and on being turned outward releases said rod so that it will slide
readily. A split ring 47 of soft metal is preferably inserted in the interior of this
split thimble to form a narrow bearing against the rod, the ring being split at a point
opposite the solid part of the thimble so as to break joint with the split thereof. This
split thimble has an actuating handle 48 by which it is turned.
The rear portion of the breech-chamber is provided with a screw-thread which
extends inward from the face of the breech a sufficient distance to give proper support
to the breech-screw.
A tubular breech-screw 49, provided with external screw-threads which take into
the screw-threads of the breech-chamber, serves to press and lock the breech-block
against its seat for closing the breech. This breech-screw constitutes a tubular set-
screw or clamping thimble which need not be removed from the gun in loading, as the
charge can be passed through it. The inner end of this tubular breech-screw rests
against the rear face of the breech-block near the circumference thereof. The inner
end of the breech-screw and the rear face of the breech-block are ground or ground
and scraped to form a tight joint. If desired the inner end of the breech-screw may
be provided with a stuffing box similar to that of the calking thimble hereinafter
described. The breech-screw is preferably tapered slightly on the outer circumference
near its inner end and an annular recess 50 is formed in the breech-chamber in which
elastic packing rings 51 are placed, the tapered end of the screw serving to spread
these rings as the screw enters. The inner ring may be of metal and the outer one of
asbestos and the metal ring is preferably split to allow it to expand after the manner
of the ring shown in figure 17. The tubular breech-screw may be seated against the
breech-block to lock it by any suitable means. One of the means shown comprises a
rack 52 attached to the outer end of the breech-screw, and a pinion 533 on a stub-
shaft 54 supported in the face of the breech near the circumference of the gun, said
pinion meshing with said rack and being actuated by a hand-lever 55. This tubular
breech-screw is sufficient in guns of ordinary caliber to lock the breech-block and in
connection with the ground joints at the front and rear faces thereof to close the breech
gas-tight without the use of packing or gas-checks.
For guns of extraordinary caliber 1 prefer to use in connection with the tubular breech-
screw 48, a tubular auxiliary breech-screw or calking thimble 56 having an external
screw-thread which takes into an internal screw-thread in the breech-screw 49. The
breech-block is provided on its rear face near its periphery with two annular
grooves 57 which form a rib 58 between them. The inner end of the auxiliary
breech-screw is provided with an annular wedge-shaped groove 59 in which a
packing 60 of soft metal, or other suitable material, is inserted. This groove con-
stitutes a stuffing box and the rib 58 on the breech-block constitutes a gland which
fits into this stuffing box. The outer face of the inner screw serves to calk the joint
between the outer screw and the breech-block, and the outer lip of the stuffing box
is preferably slit at intervals to permit lateral expansion to facilitate the calking. The
calking thimble is provided with a hand lever 61 at its outer end for tightening or
releasing the screw.
This invention also comprises an automatic gas-check embodied in, and forming a
part of, the breech-block, to which gas-check. I make special claim; but this gas-check
may be dispensed with without departing from other features of the invention. For
the purpose of this gas-check the breech-block is provided in its front face, opposite
the seat 35 at the inner end of the breech-chamber, with an annular dovetail
channel 62, which channel has a recess 63 at its bottom, and with angular gas-
ports 64, which extend from this recess forward to the front face of the block and open
into the bore of the gun. These angular ports are formed by boring inward from the
face of the block at an angle thereto and also boring in radially from the periphery of
the block to a point meeting the inclined borings. The radial portions of these ports
outside their connection with the ports 63 are closed by screw-plugs 65. Rings 66,

page_text: .
composed of steel, iron or other hard metal, are disposed in the dovetailed channel, and
a ring 67 of soft metal is inserted in said channel in front of said hard rings. The
hard rings have wedge-shaped interlapping faces. When the explosion of the charge
takes place the explosive gas passes through the angular ports 64 and through the
recess 63 into the dovetailed channel 62 and forces the rings in said channel forward
and presses the soft metal ring therein against the seat 35-surrounding the bore of the
gun, thereby tightly closing the joint between said seat and the breech-block. The
pressure of the gas also tends to spread the wedge-shaped sections of the hard metal
rings within said channel. A ring 68, which is wedge-shaped in cross-section, is
inserted in the channel between the hard metal rings and the outer soft metal ring.
This wedge-shaped ring is placed in the channel after the hard metal rings are
disposed therein, and has the effect to spread the copper ring as it is inserted
through the narrow mouth of the channel and cause it to dovetail itself within the
channel.
:
The invention also comprises an automatic gas-check embodied in, and forming a
part of, the breech-block at the rear face thereof, to which gas-check I make special
claim but this gas-check may also be dispensed with without departing from other
features of the invention. For the purpose of this gas-check, the breech-block is
provided near its rear face with an annular chamber 94 and with an annular channel 95,
which extends from said chamber to the rear face of the block opposite the inner end
of the breech-screw. Within this chamber is a flanged ring 96, and a spring or a
series of springs 97 composed of rubber. or steel are interposed between the flange of
said ring and the rear end of the chamber. A packing 98 of asbestos or other suit-
able material is disposed in the channel 95 in rear of the body of said flanged ring,
which packing is flush with or inside the rear face of the breech-block when in its
normal position. Gas-ducts 99, disposed at certain distances apart around the breech-
block, extend from the periphery of said block at an angle thereto back to the front
end of the annular chamber. The operation of this gas-check is as follows: Any
powder-gas which might possibly pass the joint at the front face of the breech-block
into the annular space between said block and the wall of the breech-chamber will
enter the inclined ducts 99, thence pass into the annular chamber 94 in front of the
flanged ring 96 within said chamber, forcing said ring rearward and thereby pushing
the packing 98 tightly against the inner end of the breech-scrow and preventing the
escape of gas past the joint of the breech-screw and breech-block. The spring or
springs 97 serve to force forward the flanged ring after the gun has been discharged,
and thereby retract the packing to its normal position flush with or within the face of the
breech-block, the packing being dovetailed into the body of the flanged ring for this
purpose. The chamber in the breech-block is formed by cutting two annular recesses
in the rear face thereof and screwing a flanged nut 100 into the inner or deeper recess.
The loading device herein described embraces certain features to which I lay special
claim; but any other loading device may be employed without departure from other
features of my invention. As shown, the loading device comprises a bracket 69
having bracket arms 70 at its inner end which are supported in eyes 71 attached
to the cap 72 which covers the face of the breoch. This bracket is provided with
bearings for a short-shaft 73 which has a pinion 74 and an actuating crank 75.
A sliding carriage 76 for conveying the projectile and charge to the bore of the
gun is provided with a rack 77 which is engaged by the pinion 74. A stop 78
on the outer end of the rack passes through a longitudinal slot in the bracket and
comes in contact with the pinion shaft and arrests the inward movement of the
carriage just as the inner end thereof comes close to the seat 35 at the inner end
of the broech-chamber. The arc-shaped body of the carriage is of the same curve
as the bore of the gun, so that the projectile or charge readily slides from the
carriage into the bore. The shaft 73 of the pinion 74 is provided with a stiff
spiral spring 79 which causes the shaft to rotate in the reverse direction, so that
the pinion automatically withdraws the carriage from the gun after the latter is
charged. The carriage is provided with a bumper 79 of rubber which comies
against a stop 79 of the bracket as the carriage is withdrawn.

page_text: One or more lubricating chambers 80 may be formed in the breech, adjacent to
the screw-threaded end of the breech-chamber. Each of these lubricating chambers
may be bored in from the face of the breech and afterward plugged at their
outer ends. Perforations S1 extend from between the threads of the breech-chamber
to these, lubricating chambers for supplying oil to the threads, and the outer
breech-screw is perforated at intervels for the passage of oil to the intermeshing
screw-threads of the calking thimble and breech-screw. These lubricating chambers
are preferably filled with cotton-wasie or some absorbent of oil and they may be
fed by removal of the plugs or preferably through feed channels 82, which extend
from the lubricating chambers to the face of the breech. These channels may be
provided with oil-cups at their outer ends. The grinding of the joints at the
front and rear faces of the breech-block in connection with the seat at the inner end
of the breech-chamber and the inner end of the tubular breech-screw, is effected
by placing the breech-block on a shaft or mandrel 84, which has a screw-threaded
portion 85 for engaging a screw-threaded hole through the center of the breech-block.
The mandrel is supported at its inner end in a disk 86 fitted within the bore of the
gun at its outer end in a larger disk 87 fitted in the breech-chamber. This mandrel
is provided at its outer end with a crank 88 by which it is turned to effect the
grinding of the joints. The breech-screw is screwed up sufficiently against the rear
face of the breech-block during the grinding operation to press said block against its
seat with sufficient force to effect the grinding of the joint between said seat and the
front face of the block, and the grinding of the inner end of said screw against the
rear face of the block takes place at the same time. When the shaft is withdrawn
from the breech-block after the joints are ground, the hole through the center thereof
is closed by a screw-threaded plug 89, which has an angular head 90, by which it is
turned into or withdrawn from the block.
For moving the breech-blocks of very heavy guns the actuating rod 43 may be
provided with a rack in its under side and a longitudinal shaft 91 may extend
from a point opposite the outer end of the breech-block chamber to the face of the
bore. This shaft 91 is provided at or near its inner end with a pinion 92 which
meshes with the rack in the rod 43 and at its outer end with an actuating
crank 93.
The operation is as follows. The split thimble 46 is turned slightly to relieve
the actuating rod 43 of the breech-block 34 and the breech-block is withdrawn
from the bore of the gun into the lateral breech-block chamber 33 by pulling said
rod. The projectile is placed upon the carriage 76 and the crank 75 is turned,
whereby the carriage is moved inward by the pinion 74 and rack 77 to the bore of
the gun, being arrested by stop 78 just before it reaches the bore. The projectile is
then pushed from the carriage into the bore, and the carriage being relieved of
the weight of the projectile, is automatically withdrawn, from the breech-chamber by
the pinion 74 and rack 77 under the action of the spring 79, which causes the shaft
to rotate in the reverse direction. The charge of powder is then inserted in the
same manner and the carriage automatically withdrawn from the gun after the latter
is charged. The breech-block is then pushed into position in rear of the bore
opposite its seats at the inner end thereof. The actuating levers 55 and 61 being
in the relative positions shown in full lines in figures 2 and 3, the lever 61 of the
calking thimble 56 is swung downward into the position indicated by dotted lines in
figure 2, whereby the calking thimble is lightly seated in and against the rear face
of the breech-block, the gland of the block entering the stuffing box of the thimble.
The lever 55 of the breech-screw is then pulled up into position indicated in dotted
lines, whereby the tubular breech-screw is turned sufficiently to seat its inner end
tightly against the outer face of the breech-block and lock the latter against the
seat 35 at the rear of the hore. The soldier in swinging down the lever 61 assumes
a bent position and in returning to an upright position he pulls up the lever 55, so
that both levers are actuated by one movement in two notions. In assuming an erect
position he can place his foot upon the lever 61 of the calking thimble, thereby bracing

page_text: himself and at the same time further tightening said thimble. The conical split
thimble 46 is then given a slight turn which tightly closes the space around the
actuating rod 43.
To open the breech after the gun is discharged the soldier grasps the breech-screw
lever, which is in the dotted line position, and swings it down into the full line
position, thereby assuming a bent attitude, and he then grasps the calking thimble
lever 61 and pulls it into its full line position assuming thereby an erect attitude. By
this one movement in two motions, the breech-block is released, and the operation
described above is repeated for reloading.
The automatic gas-check embodied in the breech-block at the rear face thereof, may
be substituted for the automatic gas-check described for the front face of the block,
the gas-ports 64 extending to the face of the block, opposite the bore, being substituted
the inclined duets 99.
for
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. A cannon body provided with a breech-chamber of larger diameter than the bore,
the shoulder at the meeting ends of the bore and breech-chamber being provided
with a solid, comparatively soft, metallic ring forming a seat for the breech-block, the
inner surface of the ring being continuous with the surface of the bore.
2. A cannon body provided with a lateral breech-block chamber having depressions
or cellars in its bottom at its opposite ends.
3. The combination of a cannon body provided with a breech-block scat at the inner
end of the bore, and with a breech-chamber provided with internal screw-threads, a
breech-block, a tubular breech-screw engaging said screw-threads for clamping said
breech-block, the joints between the breechi-block and its seat, and between the
clamping screw and breech-block being ground in unison.
4. The combination of a cannon body provided with a lateral breech-block chamber
and a sliding breech-block therein provided with a flat-faced shoe on its lower side,
said shoe being tapered at its opposite ends.
5. The combination of a cannon body provided with a lateral breech-block chamber
having an abutting screw at its inner end, and a sliding breech-block in said chamber
provided with a corresponding abutting screw.
6. The combination with a cannon body provided with a lateral breech-block
chamber, of a sliding breech-block within said chamber provided with a shoe on its
under side, and with an oil-duct extending through said block and shoe for lubricating
'the shoe.
7. The combination with a cannon body provided with a lateral breech-block
chamber closed at both ends, a breech-block sliding within said chamber, and a pull
rod extending laterally through a hole in the body of the gun into said chamber and
connected at its inner end to the breech-block.
S. The combination of a cannon body provided with a lateral breech-block chamber
.closed at both ends, a sliding breech-block within said chamber, an actuating rod
connected at one end to said breech-block and extending through a screw-threaded
hole in said body at one end of said chamber, and a conical split thimble within said
hole around said rod, substantially as set forth.
9. The combination of cannon body provided with a lateral breech-block chamber
closed at both ends, a sliding breech-block within said chamber, an actuating rod
connected at one end to said breech-block and extending through a scrow-threaded
hole in said body at one end of said chamber, and a conical split thimble within said
hole around said rod, said thimble being provided with a soft-metal split ring,
substantially as set forth.
10. The combination of a cannon body provided with a breech-block seat at the rear
of the bore and with a breech-chamber having internal screw-threads, a breech-block
adapted to rest against said seat and provided with a groove on its rear face, a tubular

page_text: breech-screw within said chamber for locking said block against its seat, and a calking
thimble provided with screw-threads which mesh with internal screw-threads of the
breech-screw, the inner end of said calking thimble resting in said groove of the
breech-block.
11. The combination of a cannon body provided with a breech-block seat in rear
of the bore and with a screw-threaded breech-chamber, a breech-block having a gland
on its rear face, a tubular breech-screw for locking the breech against its seat, and a
screw-threaded calking thimble provided with an annular stuffing box at its inner end
for receiving said gland.
12. The combination of a cannon body provided with a breech-block seat at the
inner end of the bore, and with a screw-threaded breech-chamber, a breech-block, an
annular recess in the breech-chamber in the rear of the breech-block, packing rings..
within said recess, and a breech-screw, the inner end of said screw being tapered for
forming contact with the packing rings.
13. The combination of a cannon body provided with a breech-block seat in rear of
the bore and with a screw-threaded breech-chamber, a breech-block, a breech-screw,
a calking thimble within said breech-screw, and hand levers on said breech-screw.
and calking thimbles disposed at an angle such that the full throw of the calking
lever brings the hand of the operator adjacent to the breech-screw lever.
14. A cannon body provided with a screw-threaded breech-chamber, with an oil
chamber adjacent thereto and with oil-ducts leading from said oil chamber to the
screw-threads of the breech-chamber, in combination with a breech-screw fitting such
breech-chamber, as set forth.
15. A cannon body provided with a screw-threaded breech-chamber, with an oil-
chamber adjacent thereto, with oil-ducts leading from said oil-chamber to the
screw-threads of the breech-chamber, and with an oil-duct leading from said oil-chamber.
to the face of the breech, in combination with a breech-screw seated in such breech-
chamber and suitable operating mechanism therefor, as set forth.
16. The combination with a cannon body having a breech-block seat, of a breech-
block provided in its front face opposite said seat with an annular channel, and with
ducts leading from the bottom of said channel to the front face of the block opposite
the bore of the gun, metallic packing rings within said channel, and means for locking..
said block against its seat.
17. A breech-block for a breech-loading gun provided with an annular channel in
its front face near its periphery opposite the breech-block seat, with gas-ducts leading
from said channel to the front face of the block opposite the bore of the gun, hard
metal rings disposed in said channel, and a soft metal ring, also disposed in said
channel in front of the hard rings.
18. A breech-block for a breech-loading gun provided with an annular channel in
its front face near its periphery opposite the breech-block seat, with gas-ducts leading
from said channel to the front face of the block opposite the bore of the gun, hard
metal rings disposed in said channel, and a soft metal ring, also disposed in said.
channel in front of the hard rings, said hard metal rings being wedge-shaped in
cross-section.
19. The combination of a cannon body, a bracket hinged to said body at the breech
thereof, a transverse shaft supported on said bracket, a pinion on said shaft, an
actuating crank also on said shaft, and a sliding carriage on said bracket provided with
a rack with which said pinion engages.
20. The combination of a cannon body, a bracket at the breech thereof, a transverse
shaft supported on said bracket, a pinion on said shaft, an actuating crank also on
said shaft, a sliding carriage on said bracket provided with a rack with which, said
pinion engages, and a spring on said shaft which operates to turn the shaft to
automatically retract the carriage from the gun.
21. The combination of a cannon body, a bracket hinged to said body at the breech
thereof, a transverse shaft supported on said bracket, a pinion on said shaft, an
actuating crank also on said shaft, and a sliding carriage on said bracket provided with

page_text: a rack with which said pinion engages, said carriage having a stop for arresting its
movement at the rear end of the bore.
22. The combination of a cannon body, a bracket hinged to said body at the breech
thereof, a transverse shaft supported on said bracket, a pin on on said shaft, an
actuating crank also on said shaft, and a sliding carriage on said bracket provided
with a rack with which said pinion engages, and a stop at the rear end of said bracket
for arresting the outward movement of the carriage.
23. The combination of a cannon body provided with a lateral breech-block chamber,
a laterally sliding breech-block, a pull rod connected at its inner end to said breech-
block and provided with a rack; a longitudinal shaft journaled within the body of the
gun provided at its inner end with a pinion which meshes with said rack and at its
outer end with an actuating crank.
24. The combination of a cannon body provided with a breech-block seat at the
rear of the bore and with a breech-chamber having internal screw-threads, a breech-
block; a tubular breech-scrow within said chamber for locking said block against
its seat, and a calking thimble provided with screw-threads which mesh with internal
screw-threads of the breech-screw, the inner end of said calking thimble resting
against the breech-block:
25. The combination of a cannon body provided with a breech-block seat at the
rear of tlie bore and with a breech-chamber having internal screw-threads, a breech-
block provided with a groove on its rear face; a tubular breech-screw within said
chamber for locking said block against its seat and a screw-threaded calking thimble
within the breech-screw, the inner end of said calking thimble having a split lip which
projects into said groove of the breech-block.
26. The combination of a cannon body provided with a breech-block seat and with
a screw-threaded breech-chamber, a breech-block for closing the bore provided with
an annular recess in its rear face and with gas-ducts leading from said recess to the
periphery of said block, a gas-check ring within said recess, and a breech-screw for
locking said block.
27. A breech-block for a breech-loading gun provided with an annular chamber
near its rear face, ducts extending from said chamber to the periphery of the block,
an annular channel in the rear face of the block communicating with said chamber,
and packing rings within said channel and chamber.
28. A breech-block for a breech-loading gun provided with an annular chamber
near its rear face, ducts extending from said chamber to the periphery of the block,
an annular channel in the rear face of the block communicating with said chamber, a
flanged packing ring within said chamber, packing within said channel connected with
said flanged ring and a spring or springs interposed between the flange of said ring
and the rear face of said chamber for retracting the packing within the face of
the block.
29. The combination of a cannon body provided with a breech-block seat in rear
of the bore; a breech-block for closing said bore, an automatic gas-check at the
front face of the breech-block; an automatic gas-check at the rear face of said block
and a breech-screw for locking said block against its seat.
30. The combination of a cannon body provided with a breech-block seat in rear of
the bore and with a screw-threaded breech-chamber, a breech-block, an automatic gas-
check, at the front face of said breech-block, an automatic gas-check at the rear of said
breech-block, a tubular breech-screw for locking the breech-block against its scat,
and a screw-threaded calking thimble within the breech-screw, the inner end of
which is seated against the breech-block.
31. The combination of a cannon body provided with a breech-block seat in rear
of the bore and with a screw-threaded breech-chamber, a breech-block for closing the
bore, an automatic gas-check at the front face of the breech-block, an automatic gas-
check at the rear face of the breech-block, said breech-block, being provided with an
annular gland on its rear face, and a screw-threaded calking thimble within the breech-
screw provided at its inner end with an annular stuffing box which fits over said gland.

page_text: 32. The combination of a cannon body provided with a breech-block chamber and a
breech-block seat at the rear end of the bore, a breech-block within said chamber and
means for clamping said breech-block to said seat, the front face of said breech-block
and the rear face of said seat being ground in unison.
33. The combination of a cannon body provided with a breech-block seat at the rear
end of the bore and with a breech-block chamber having internal screw-threads and a
tubular breech-screw engaging said screw-threads for clamping said breech-block against
its sent, the rear face of said breech-block and the inner end of said breech-screw being
ground in unison.
34. A cannon constructed substantially as heroin set forth.