IMPROVEMENTS IN REVOLVING CANNON AND OTHER GUNS
Year: 1879

page_text: LETTERS PATENT to Benjamin Berkley Hotchkiss, of 38, Southampton Buildings,
Chancery Lane, London, Engineer, for the Invention of "IMPROVEMENTS IN
REVOLVING CANNON AND OTHER GUNS."
PROVISIONAL SPECIFICATION left by the said Benjamin Berkley Hotchkiss
at the Office of the Commissioners of Patents on the 1st November 1879.
BENJAMIN BERKLEY HOTCHKISS, of 38, Southampton Buildings, Chancery Lane,
London, Engineer. IMPROVEMENTS IN REVOLVING CANNON AND OTHER GUNS."
"
This Invention refers more particularly to improvements in revolving cannons,
but some of its parts are applicable also to other classes of cannons, and even to fire
arms in general; but I will here describe and have shewn in the five Figures
of Drawings accompanying this Specification the improvements as applied to a
revolving cannon.
In these Drawings is,—
Figure 1, a longitudinal elevation of a revolving cannon, some parts being repre-
sented in section.
Figure 2 is a plan of some details.
Figure shews a modification in elevation of some of the parts shewn in
Figure 1.
These three Figures represent the first part of my Invention, which has reference
to means for elevating the gun.
Figure 3 is a longitudinal sectional elevation of a similar gun; and Figure 4 is a
cross section of the same taken near the rear end of the piece through the chamber
of the mechanism.
These last two Figures illustrate the second part of the Invention, having reference
to the manner in which the discharge is effected.
FIRST IMPROVEMENT-MECHANISM FOR ELEVATING OR POINTING THE CANNON.

page_text: shoulder piece S both with regard to the elevation and to the lateral direction,
becomes very fatiguing. To obviate this difficulty and to render a more accurate
pointing possible I arrange a mechanism under the piece, by means of which the
elevation can be regulated with extreme facility without tiring the gunner, and
which permits the piece to be invariably left at the elevation required. For this
purpose I arrange on the rear under part of the gun a segment A with inside teeth;
with this segment engages a worm B, the shaft of which turns in the arm C,
extending from the forked support or pivot piece U, and carries a pinion b, with
which engages the worm D fixed on the shaft d, which extends backward toward
the left of the gunner, and at the same time slightly downward, and carries on its
free extremity a hand wheel or crank d' in convenient position to be readily grasped
and manipulated by the gunner. As the worm B with its pinion b cannot be dis-
placed vertically in the line of its axis, it follows that the rotation of the hand
wheel d¹, and consequently of the pinion b and worm B, must cause the segment A,
and with it the rear part of the piece, to rise or fall, whereby the desired elevation of
the cannon can be obtained.
On
When points of widely different elevations have to be aimed at in rapid succes-
sion, this method of sighting would however prove too slow; in such cases, to obtain
satisfactory results, the ability of the gunner alone can be relied upon, who will
then have to effect the pointing by seizing the piece directly at any convenient
point, and by moving it with his hand, whereby the shoulder piece S will afford
considerable aid; but for this purpose the rack A has to be disengaged from the
worm B. To effect this, instead of fixing the rack rigidly on the body of the piece,
I attach it thereto by means of a knuckle joint E, so that under certain conditions
it can swing backwards away from the worm B. On the arm C I form a projec-
tion c, having a slot through which the rack passes downward, and which is also of
sufficient length to permit a certain amount of swinging motion of the rack.
the projection c, opposite the exterior or smooth edge of the rack, I adapt a cam F of
the form represented, the shaft of which extends laterally outward, and carries on
its extremity a small hand crank f. When this crank is in the position represented
in full lines the cam F presents its full side toward the edge of the rack A, and
holds the same pressed inward in gear with the worm B, but when the handle f is
turned into the position indicated by dotted lines the cut-out part of the cam F
permits the rack to recede backwards in obedience to the spring a fixed thereon, as
shewn, and now, the rack being brought out of contact with the worm B, the piece
is free to follow any impulse given to it by the hand or shoulder of the gunner. To
again engage the parts and make the piece relatively fixed it is only necessary to
turn the crank back again into its original position; thereby the cam F will again
press the rack in contact with the worm in opposition to the force of the spring a,
and hold it firmly engaged as long as desired.
Another manner of carrying out this object is shewn in Figure 5. According to
this construction the rack is formed with a slot concentric to the pitch line of the
teeth, and through this slot passes an excentric or crank pin F', extending from the
end of the shaft carrying the hand crank f. The rack A is hinged to the rear end
of the piece in the same manner as in Figure 1, but the spring a is omitted, this
element being rendered superfluous, as the pin F¹ acting against one side or the
other of the slot in the rack A, according to the direction in which the handle fis
turned, serves to positively move the rack into or out of gear with the worm B, and
to hold it firmly in the required position. The other parts of the apparatus con-
structed with this modification are or may be exactly the same as those represented
in Figures 1 and 2, and are therefore not repeated in Figure 5.
SECOND IMPROVEMENT-MECHANISM FOR EFFECTING THE DISCHARGE.
Bicures 2 and 4

page_text: also all the other parts of the mechanism of the piece are operated. In guns of
heavier calibers it has been found that the operations of pointing the gun and also
working the mechanism cannot well be performed by one and the same man; there
are other machine guns which also require the manipulation of more than one man,
and the object of these improvements is to give the pointer of the gun the help of
other men in elevating, or depressing, or working the gun, and at the same time,
by the aid of a trigger in connection with the mechanism, to enable the pointer to
avail himself of the supernumary aid mentioned, whilst he himself and alone has
the power of arresting their movements, and of discharging the gun himself and
unaided. Such guns have therefore been operated by two men, one of which effected
the pointing, whilst the other turned the crank; but from this combined operation
resulted the inconvenience that the firing of the piece did not always take place at
exactly the moment desired, because it could not be sufficiently controlled by the
pointer. I obviate this difficulty by an arrangement whereby the pointing and
the firing of the gun are accomplished by one man, whilst the second man imparts
only the motive power to work the gun. For this purpose the parts are so arranged
that the rotation of the crank, besides the loading, revolving of the barrels, and
extracting of the shells, effects only the backward movement of the firing pin, what
might be termed the cocking of the gun, then the parts of the mechanism arrive in
such position that the further turning of the crank is rendered impossible until the
gun is discharged, which is effected, according to this part of the Invention, after
pointing the piece, by a slight movement of the finger of the pointer acting on a
piece corresponding to the trigger of a rifle. To obtain this result I arrange under
the rear of the cannon a handle V, which may be formed more or less in the shape
of a pistol grip, and which carries in a manner somewhat corresponding to the
arrangement of a pistol or rifle a trigger H, preferably protected by a trigger guard,
as shewn, and to the front end of which is hinged the pin h, which extends up-
wards through a hole formed in the metal of the case of the cannon mechanism,
and the bevilled end of which penetrates into the canal formed as a guide for
the firing pin. A spring I pressing against a tail piece formed on the trigger H
tends to hold the extremity of the pin h constantly projecting in the interior of
the firing pin canal. On the arm w of the firing pin W, which is acted upon by
the cam J, I form a small projection facing toward the lateral surface of the worm
K, and on this latter surface I form a second small projection or stop 8. in such
position that when the firing pin is moved backwards to its full extent by the
cam J, and when it is then attempted to turn the shaft G and consequently the
cams I and K still further, this stop s strikes against the projection formed on
the arm w of the firing pin W, and thus prevents the further rotation of the
shaft G.
The operation of this mechanism is as follows:-Supposing the firing pin to be
in the forward position, having struck and ignited a cartridge in the barrel
presented in position. When the shaft G is now turned by the gunner or by an
assistant by means of the crank G', the revolution of this shaft will cause the firing
pin W to be pushed backward by the cam J acting on its arm w, and at the same
time the worm K will cause the barrels to revolve so as to present the following
barrel to the action of the firing pin, all in the ordinary manner; but during the
backward motion of the firing pin the enlarged part thereof near its rear end, which
serves at the same time as a guide acting on the inclined face of the projecting pin h,
pushes the same downward in opposition to the force of the spring I. At the end
of the backward stroke of the firing pin, when one revolution of the shaft G is nearly
completed, the head of the pin / being liberated rises in front of the swell formed
on the firing pin, thus retaining the latter in the rear, even when on further turning
the shaft G the cam J leaves the arm of the firing pin. At that moment, when the
cam J ceases to touch the said arm w, the lateral projection s formed on the cam K
strikes against the corresponding projection on the arm w of the firing pin, and thus
prevents the further rotation of the shaft G. Under these conditions the piece is
what may be termed cocked, and the gunner, if he has not previously done so, has

page_text: now full time to point his piece, and can thereupon, without causing the slightest
disturbance by bringing any heavy parts of the mechanism in motion, discharge
the barrel at any desired moment by a slight pressure with his finger exerted on
the trigger H, whereby the pin h is pulled downward, thus liberating the firing
pin, which plies forward with the force imparted to it by its spring in the usual
manner to effect the discharge. At this forward motion of the firing pin the pro-
jection on its arm w slides away from over the stop s formed on the lateral face of
the worm K, thus liberating the same, and leaving the parts free to be operated
again in the manner described by a new revolution of the shaft G. In order to
facilitate the release of the firing pin W the upper surface of the stop 8 and the under
surface of the projection on the arm w are slightly bevilled. If continuous firing
is desired at any moment, the pointer has only to hold the trigger down firmly, and
order the crank to be turned continuously.
I do not limit myself to this particular mode of construction, as it is obvious that
other means may be arranged producing exactly the same result, viz., making the
striking motion of the firing pin independent from the general mechanism, and
placing it entirely under the direct control of the gunner by means of a trigger or
its equivalent.
THIRD IMPROVEMENT-ARRANGEMENT OF THE SIGHT.
Heretofore the numbers of the sights of all kinds of fire-arms have been produced
thereon by means of engraving the same in the metal. This method must be con-
sidered as very defective, in so much that such engraved numbers are under some
circumstances, specially at night, difficult to read, and become often by some
accident or atmospheric influences absolutely illegible. I replace therefore these
engraved sights by novel ones, which are formed of a plate of metal enamelled in a
bright colour, preferably white, and on which the letters or other marks are written
also in enamel, but of a colour having a strong contrast from the ground colour.
When the ground is, for instance, white, the marks will by preference be black;
but it is evident that any other colours may be used with nearly equally good
results. These sights are not only much more plainly visible when new, but they
are also very durable, and can under no ordinary conditions lose their superior
qualities.
Heretofore the numbers of the sights of all kinds of fire-arms have been produced
thereon by means of engraving the same in the metal. This method must be con-
sidered as very defective, in so much that such engraved numbers are under some
circumstances, specially at night, difficult to read, and become often by some
accident or atmospheric influences absolutely illegible. I replace therefore these
engraved sights by novel ones, which are formed of a plate of metal enamelled in a
bright colour, preferably white, and on which the letters or other marks are written
also in enamel, but of a colour having a strong contrast from the ground colour.
When the ground is, for instance, white, the marks will by preference be black;
but it is evident that any other colours may be used with nearly equally good
results. These sights are not only much more plainly visible when new, but they
are also very durable, and can under no ordinary conditions lose their superior
qualities.

page_text: through which the rack passes downward, and which is also of sufficient length to
permit a certain amount of swinging motion of the rack. On the projection c,
opposite the exterior or smooth edge of the rack, I adapt a cam F of the form repre-
sented, the shaft of which extends laterally outward, and carries on its extremity a
small hand crank f. When this crank is in the position represented in full lines the
cam F presents its full side toward the edge of the rack A, and holds the same
pressed inward in gear with the worm B, but when the handle f is turned into the
position indicated by dotted lines the cut out part of the cam F permits the rack to
recede backwards in obedience to the spring a fixed thereon, as shown, and now,
rack being brought out of contact with the worm B, the piece is free to follow any
impulse given to it by the hand or shoulder of the gunner. To again engage the
parts and make the piece relatively fixed it is only necessary to turn the crank f
back again into its original position; thereby the cam F will again press the rack
in contact with the worm in opposition to the force of the spring a, and hold it
firmly engaged as long as desired.
the
Another manner of carrying out this object is shown in Figure 5. According to
this construction the rack is formed with a slot concentric to the pitch-line of the
teeth, and through this slot passes an excentric or crank pin F, extending from the
end of the shaft carrying the hand crank f. The rack A is hinged to the rear end
of the piece in the same manner as in Figure 1, but the spring a is omitted, this
element being rendered superfluous, as the pin F1 acting against one side or the
other of the slot in the rack A, according to the direction in which the bandle f is
turned, serves to positively move the rack into or out of gear with the worm B, and
to hold it firmly in the required position. The other parts of the apparatus con-
structed with this modification are or may be exactly the same as those represented
in Figures 1 and 2, and are therefore not repeated in Figure 5.
SECOND IMPROVEMENT-MECHANISM FOR EFFECTING THE DISCHARGE.
Figures 3 and 4.
As actus estructed, the discharge of the revolving cannon is effected by the
continued turni of the crank G¹ on the outer extremity of the shaft G, whereby
also all the other parts of the mechanism of the piece are operated. In guns of
heavier calibres it has been found that the operations of pointing the gun and also
working the mechanism cannot well be performed by one and the same man; there
are other machine guns which also require the manipulation of more than one man,
and the object of these improvements is to give the pointer of the gun the help of
other men in elevating, or depressing, or working the gun, and at the same time,
by the aid of a trigger in connection with the mechanism, to enable the pointer to
avail himself of the supernumary aid mentioned, whilst he himself and alone has
the power of arresting their movements, and of discharging the gun himself and
unaided. Such guns have therefore been operated by two men, one of which effected
the pointing, whilst the other turned the crank; but from this combined operation
resulted the inconvenience that the firing of the piece did not always take place at
exactly the moment desired, because it could not be sufficiently controlled by the
pointer. I obviate this difficulty by an arrangement whereby the pointing and
the firing of the gun are accomplished by one man, whilst the second man imparts
only the motive power to work the gun. For this purpose the parts are so arranged
that the rotation of the crank, besides the loading, revolving of the barrels, and
extracting of the shells, effects only the backward movement of the firing pin, what
might be termed the cocking of the gun, then the parts of the mechanism arrive in
such position that the further turning of the crank is rendered impossible until the
gun is discharged, which is affected, according to this part of the Invention, after
pointing the piece, by a slight movement of the finger of the pointer acting on a
piece corresponding to the trigger of a rifle. To obtain this result I arrange under
the rear of the cannon a handle V, which may be formed more or less in the shape
of a pistol grip, and which carries in a manner somewhat corresponding to the

page_text: arrangement of a pistol or rifle a trigger H, preferably protected by a trigger guard,
as shown, and to the front end of which is hinged the pin h, which extends up-
ward through a hole formed in the metal of the case of the cannon mechanism,
and the bevilled end of which penetrates into the canal formed as a guide for the
firing pin. A spring I pressing against a tail piece formed on the trigger H tends
to hold the extremity of the h constantly projecting in the interior of the firing
pin canal. On the arm w of the firing pin W, which is acted upon by the cam J, I
form a small projection facing toward the lateral surface of the worm K, and on this
latter surface I form a second small projection or stop s in such position that when
the firing pin is moved backwards to its full extent by the cam J, and when it is
then attempted to turn the shaft G, and consequently the cams J and K still further,
this stop 8 strikes against the projection formed on the arm w of the firing pin W,
and thus prevents the further rotation of the shaft G.
The operation of this mechanism is as follows:-Supposing the firing pin to be
in the forward position, having struck and ignited a cartridge in the barrel presented
in position. When the shaft G is now turned by the gunner or by an assistant by
means of the crank G¹, the revolution of this shaft will cause the firing pin W to be
pushed backward by the cam J acting on its arm w, and at the same time the
worm K will cause the barrels to revolve so as to present the following barrel to
the action of the firing pin, all in the ordinary manner. But during the backward
motion of the firing pin the enlarged part thereof near its rear end, which serves at
the same time as a guide acting on the inclined face of the projecting pin h, pushes
the same downward in opposition to the force of the spring I. At the end of the
backward stroke of the firing pin, when one revolution of the shaft G is nearly
completed, the head of the pin being liberated rises in front of the swell formed
on the firing pin, thus retaining the latter in the rear, even when on further turning
the shaft G the cam J leaves the arm of the firing pin. At that moment, when the
cam J ceases to touch the said arm w, the lateral projection s formed on the cam K
strikes against the corresponding projection on the arm wof the firing pin, and thus
prevents the further rotation of the shaft G. Under these conditions the piece is
what may be termed cocked, and the gunner, if he has not previously done so, has
now full time to point his piece, and can thereupon, without causing the slightest
disturbance by bringing any heavy parts of the mechanism in motion, discharge the
barrel at any desired moment by a slight pressure with his finger exerted on the
trigger H, whereby the pin h is pulled downward, thus libérating the firing pin
which flies forward with the force imparted to it by its spring in the usual manner
to effect the discharge. At this forward motion of the firing pin the projection on
its arm w slides away from over the stops formed on the lateral face of the worm K,
thus liberating the same, and leaving the parts free to be operated again in the
manner described by a new revolution of the shaft G. In order to facilitate the
release of the firing pin W the upper surface of the stops and the under surface of
the projection on the arm w are slightly bevelled. If continuous firing is desired
at any moment the pointer has only to hold the trigger down firmly and order the
crank to be turned continuously.
I do not limit myself to this particular mode of construction, as it is obvious
that other means may be arranged producing exactly the same result, viz., making
the striking motion of the firing pin independent from the general mechanism, and
placing it entirely under the direct control of the gunner by means of a trigger or
its equivalent.
THIRD IMPROVEMENT ARRANGEMENT OF THE SIGHT.

page_text: '
by novel ones, which are formed of a plate of metal enamelled in a bright colour,
preferably white, and on which the, letters or other marks are written also in
enamel, but of a colour having a strong contrast from the ground colour. When
the ground is for instance white, the marks will by preference be black. But it is
evident that any other colours may be used witli nearly equally good results.
These sights are not only much more plainly visible when new, but they are also
very durable, and can under no ordinary conditions lose their superior qualities.
I claim as my Invention,―
First. In a revolving cannon or other system of gun the rack A attached to the
rear part of the piece in combination with the worms and suitable operating means
carried on a suitable arm fixed on the support U, which participates in the horizontal
movement of the piece when it is pointed, but is not affected by its vertical move-
ment, substantially as described and shown and for the purposes set forth.
Second. A rack A hinged to the body of the cannon in combination with the
worms and their operating means, and with a cam F serving to engage the said
rack with or liberate it from the worm B in conjunction with the spring a,
substantially as shown and described and for the purposes set forth.
Third. The mode of bringing the rack A in and out of gear of the worm B by
slotting the said rack and adapting within the said slot the pin F¹ fitted excentrically
on the shaft of the hand crank f in such a manner that, according to one position
of the latter, the rack will be geared with the worm, and according to another
position it will be out of gear, and positively maintained in either of these two
positions.
Fourth. A revolving cannon or other system of machine gun in which the
liberation of the firing pin is effected for producing the discharge by means under
the direct control of the gunner, and absolutely independent from the working of
the general mechanism of the piece, substantially as described.
Fifth. On a revolving pon or other system of machine gun the trigger H,
arranged substantially as s vn, and acted upon by the spring I, which trigger
serves either directly or thi h an intermediate pin h to hold the firing pin in the
cocked position, and permits the firing of the gun without having recourse to the
ordinary mechanism, substantially as set forth and shown.
Sixth. The trigger H with its spring I or equivalent means serving to arrest
and liberate the firing pin in combination with the two projections, one on the firing
pin arm w and the other s on the face of the worm K, which prevents the
continuance of the revolution of the shaft G when the piece is cocked, substantially
as set forth and shown.
Seventh. A sight for fire arms consisting of an enamelled metal plate with the
numbers or other marks thereon equally in enamel but of a marked different
colour.
Eighth. I claim the construction of a machine gun so arranged that single shots
or repeated shots can be fired by the use of a trigger, or by holding on to the
trigger the guns may be fired continuously, substantially as in the manner
described.
In witness whereof, I, the said Benjamin Berkley Hotchkiss, have hereunto
set my hand and seal, this Sixteenth day of April, in the year of our Lord
Witnesses,
D. H. BRANDON,
TH. FAVARGER.
B. B, HOTCHKISS. (L.S.)