IMPROVEMENTS IN THE MECHANISM OF AND IN THE MODE OF SUPPORTING ROCK-DRILLING MACHINES
Year: 1874

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn Fields,
in the County of Middlesex, Gentleman, for the Invention of
"IMPROVEMENTS IN THE MECHANISM OF AND IN THE MODE OF SUPPORTING
ROCK-DRILLING MACHINES."- - A communication from abroad by
John B. Waring, of the City of New York, United States of
America.
-
Sealed the 10th July 1874, and dated the 14th May 1874.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson
at the Office of the Commissioners of Patents, with his Petition,
on the 14th May 1874.
I, JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the
County of Middlesex, Gentleman, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN THE MECHANISM OF AND IN THE MODE
OF SUPPORTING ROCK-DRILLING MACHINES," a communication to me from
abroad by John B. Waring, of the City of New York, United States of
America, to be as follows:-
This Invention relates to rock-drilling machines in which the drill rod

page_text: or plunger is operated by steam or compressed air, and in the mode of
supporting the same, and consists,-
Firstly. In operating the valve on which depends the reciprocating
action of the drill rod directly from the piston by simple mechanism,
which will permit the free rotation of the said piston and of the drill rod
which forms a part of the same.
Secondly. In an improved construction of tool holder formed of two
parts or of one part split throughout the greater portion of its length,
and confined by bolts and by a ring having a flaring flange for shielding
the stuffing box of the cylinder from the detritus which is discharged
from the hole in which the tool is operating. Also a peculiar arrange-
ment of mechanism for imparting a direct movement to the piston rod
in a forward direction, but turning the same during its rearward motion
and for feeding the centre cylinder and its appliances forward in its
ways with ease, when a longer forward movement of the piston than
usual is required by the drilling tool meeting with a crevice in the
rock.
And, Thirdly. In the construction of a tripod for supporting the
machine by which it can be readily adjusted to and retained in any
position which the direction of the hole to be drilled may suggest, an
especial feature of this part of the Invention being the ready adjustment
by means of ball-and-socket joints of the legs to such cavities in the rock
as may present themselves.
In describing the first part of this Invention it will be understood
that midway or thereabout between the opposite ends of the cylinder of
a rock drilling machine, are the depressed valve faces or seats separated
from each other by an opening extending therefrom through to the bore
of the cylinder. In these valve faces or seats are two inlet ports and
two exhaust ports, the ports of one valve face or seat communicating
with one end of the cylinder, and those of the other face or seat with
the opposite end of the cylinder. The steam chest enclosing the valve
faces or seats, and also the form and direction of the inlet and outlet
passages to and from the cylinder being of the usual construction will
be readily understood by those familiar with rock drilling machinery
without further description.
The piston of the cylinder consists of two collars formed at some
distance apart on a rod which passes through a stuffing box in the

page_text: cylinder head, and which constitutes the drill rod for receiving at its
outer end the usual boring tool. This piston must not only be at liberty
to reciprocate freely in the cylinder, but must admit of being turned
therein as the requirements of the boring tool demand, and the main aim
of this Invention is to permit the piston to be rotated freely, and at the
same time to cause it to impart the desired transverse reciprocating
motion to the valve. This is brought about mainly through the
intervention of what may be termed a "sleeve," which in the present
instance is made in halves for ready adjustment to the piston rod to
which it is fitted between the collars thereof, so that while it can have
no longitudinal movement independently of the piston the latter can
turn freely in the sleeve which has a cam slot for receiving a central lug
formed on the under side of a valve of the duplex character so constructed
and so adapted to the seats and ports and has such a reciprocating action
imparted to it by the action of the cam slot in the said sleeve as to
direct steam or compressed air admitted to the chest, inclosing the valve
alternately to and exhaust it alternately from the opposite ends of the
cylinder. It is essential however that the sleeve in order that it may be
an effective medium through which the piston actuates the valve should
be prevented from turning. This is accomplished in the present instance.
by a frame consisting of two parallel bars connected together at right
angles by strips underneath the said bars. This frame is adapted to the
cylinder by its parallel bars being fitted to the corners of the recessed
valve faces or seats and serving as guides for the valve, the strips
connecting the said bars passing through the opening in the cylinder
between the valve faces or seats and projecting into longitudinal parallel
slots formed in the sleeve, so that the said sleeve is thereby prevented
from turning without interfering with its longitudinal movement.
It is not essential that the sleeve should entirely surround the piston
rod between the collars; one half for instance may be dispensed with,
leaving the other portion or plate to perform the duties explained
above, but it is preferred to use both portions which together insure a
more uniform wear of the piston.
In place of the cam slot a groove or ways may be formed in the sleeve
or its equivalent for acting on the lug or projection of the valve.
The character of the differential or intermittent reciprocating
movement of the valve will depend on the form of the slot or ways of

page_text: the sleeve, and the movement of the valve may have to be changed in
accordance with the character of the blow to be imparted by the drilling
tool or in accordance with the point in the stroke where it is desirable to
cut off the steam or compressed air; hence it is preferred in all cases to
so make the sleeve that it can be readily removed to make way for a
different sleeve, as in the present instance.
"
In the second part of this Invention the tool holder carried by the
outer end of the piston rod is made in two parts, or in one part split
throughout the greater portion of its length, the two parts being secured
together at the tool or front end by bolts, so as to embrace the drilling 1
tool, the tapering back end of the holder being encircled by a ring, the
tightening of which on the tool. holder is insured by the striking of the
drilling tool against the rock. This ring has a flaring flange which
shields the stuffing box of the cylinder from the detritus which is
discharged from the hole in which the tool is operating.
The piston rod passes through a sleeve inserted into a contracted
chamber at one end of the cylinder between it and the stuffing box, and
has spiral grooves and ribs corresponding with similar grooves or ribs in
the sleeve.
The forward movement of the piston rod will be in a direct course, the
sleeve turning and accommodating itself to the rod, but on moving back
the rod must turn owing to a clutch in combination with the said sleeve,
a portion of which clutch is stationary and secured within and to the
cylinder, whilst its other part turns with the sleeve and is furnished withi
inclined teeth on its face, which engage with corresponding teeth on the
face of the stationary portion of the clutch in such a manner that when
forced by a spring against the latter, and the piston rod moves forward
the teeth on its face slip over the teeth on the stationary part of the
clutch, thereby causing the moveable part to turn idly with the said
sleeve on the piston rod, but when the latter is moving backwards the
moveable part of the clutch, and with it the sleeve, are held fast by the
teeth of the stationary part, and the piston rod is consequently compelled
to rotate by the action of the said ribs or grooves.
The piston is chambered for the reception of a second sleeve which
has grooves adapted to corresponding projections on the piston; these
grooves being straight throughout the greater portion of their length,
but curved or spiral near their termination.
]

page_text: Under ordinary circumstances the projections on the piston do not
reach the spiral portions of the grooves on the second sleeve, but should
the drilling tool reach a crevice in the rock, and a longer forward
movement of the piston than usual takes place, the projections on the
latter reaching the said spiral portion of the grooves will turn the second
sleeve, and by means of a clutch, similar to that previously described,
will turn a nut inserted in the other end of the cylinder, and working
over a long screw extending externally to the cylinder, and fixed to a
convenient part of the frame of the machine so as to cause the entire
cylinder and its appliances to feed or move forward, the cylinder being
adapted to ways in the frame which is secured to a tripod in the manner
hereafter described. The said screw is connected to the frame through
the medium of an arm, and the second sleeve is so confined to the
cylinder that while it can turn freely it can have no longitudinal
movement, the nut being also confined in the head of the cylinder, and
so combine with the said clutch that the sleeve can turn in one direction
independently of the nut, but must be accompanied with the latter when
turned in the opposite direction.
The third part of this Invention which relates to an improved tripod
for supporting the rock drilling machine consists of three legs supporting
a frame or shell which in the present instance is of a semi-cylindrical
form and has guides or ways for receiving corresponding projections or
ribs on the cylinder of the rock-drilling machine. Each leg of the tripod.
consists of an external tube of wrought iron and an internal rod so fitted
to the tube that it can be turned freely and adjusted longitudinally
therein, and secured after adjustment by a set screw passing through a
collar or enlargement at the lower end of the tube.
The forked upper end of the rear leg is adapted to a bolt which passes.
through the cylindrical portion of a second frame forming the top of
the tripod and having two arms, to each of which one of the front
legs is connected in the following manner:-A socket is formed on the.
end of each arm, into which is inserted a ball or sphere formed on or
attached to the upper end of each of the front legs of the tripod, the
said ball or sphere being confined to its place by a plate or follower
acted on by a screw passing through a plate or cover screwed into the
top of the said socket. It will thus be observed that each front leg is
connected to the said second frame by a ball-and-socket joint which
permits the leg to be moved in any direction the joint being readily
1

page_text: made permanent after adjustment by the said screw through the plate
or cover. The frame or shell just mentioned is connected to the second
frame of the tripod in this manner:-A circular dovetailed recess is
formed on the under side of the said frame or shell, and to this recess is
adapted a circular projection having a corresponding edge, one half of
the projection being formed on one half and the other on the other half
of a clamp embracing the cylindrical portion of the above mentioned
second frame, the two portions of the clamp being connected and
tightened together on the latter by a bolt hinged to the lower lug or lip
of one half of the clamp and adapted to a slot in the lug or lip of the
other half where it is fitted with a nut, the tightening of which against
the clamp expands or separates the two half portions of the circular pro-
jection of the clamp against the surface of the circular dovetailed recess,
and thus secures the frame or shell to the second frame of the tripod,
and the loosening of the nut of the bolt permits such a contraction of
the said portions of the projection that they can be withdrawn from the
said recess, or the clamp can be so loosened as to permit the frame or
shell to be turned laterally to any desired position without detaching it
from the tripod, after which adjustment it may be secured by simply
tightening the clamp in the manner described.
The main feature of this Invention however is the attachment of the
front legs of the tripod to the second frame by means of ball-and-socket
joints, for these joints permit the ready adjustment of the lower pointed
ends of the legs to any cavity in the rock which may be present, and so
affords a secure lodgment for the said pointed ends of the legs. After
the tripod, for instance, has been placed in the position determined by
the direction in which the hole has to be bored it may be found that
one of the legs has not a secure lodgment, in which case it may be
adjusted to any neighbouring cavity without any change in the position
of the frame or shell, for the leg must be elongated or contracted in
accordance with its position as determined by the cavity. This adjust-
ment of the tripod may be in a measure effected by connecting one of
its legs only to the second frame with a ball-and-socket joint, or all the
legs may be thus connected to the said frame, but it is found best in
practice to confine these joints to the two front legs described above.
In many cases it is necessary to so adjust a rock drill that it will bore
holes near the ground, hence the adjustable rod of cach leg is provided
with an adjustable spur or short leg sliding on and at right angles to the

page_text: said adjustable rod so that the legs may be outstretched to permit the
depression of the frame or shell, in which case the said spurs are
adjusted to cavities in the rock.
It is necessary when the rock drill is in operation that the tripod
should be weighted, for which purpose cach leg is furnished with a
hooked projection carrying a weight and adapted to a recess therein, the
said weight also having a groove for receiving and being steadied
laterally by the leg from which the weight can be readily detached.
It will be noted without further description that the frame or shell
and consequently the drilling machine attached to it can be vibrated
freely on the cylindrical portion of the second frame and can be turned
laterally on the circular projection of the clamp while the legs afford
ample opportunities for the vertical'adjustment of the frame or shell.
:
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Henry Johnson in the Great Seal Patent
Office on the 5th November 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of
Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fourteenth day of May, in the year
of our Lord One thousand eight hundred and seventy-four, in the.
37th year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, 'the said John Henry Johnson, Her special
license that I, the said John Henry Johnson, my executors, admi-
nistrators, and assigns, or such others as I, the said John Henry
Johnson, my executors, administrators, or assigns, should at any time
agree with, and no others, from time to time and at all times thereafter
.during the term therein expressed, should and lawfully might make,
use, exercise, and vend, within the United Kingdom of Great Britain
and Ireland, the Channel Islands, and Isle of Man, an Invention for
"IMPROVEMENTS IN THE MECHANISM OF AND IN THE MODE OF SUPPORTING ROCK-
DRILLING MACHINES," a communication to me from abroad by John

page_text: B. Waring, of the City of New York, United States of Americà, upon
the condition (amongst others) that I, the said John Henry Johnson,
my executors or administrators, by an instrument in writing under my
hand and seal, should particularly describe and ascertain the nature
of the said Invention, and in what manner the same was to be performed,
and cause the same to be filed in the Great Seal Patent Office within
six calendar months next and immediately after the date of the said
Letters Patent.
NOW KNOW YE, that I, the said John Henry Johnson, do hereby
declare the nature of the said Invention, and in what manner the
same is to be performed, to be particularly described and ascertained in
and by the following statement, reference being had to the accompanying
Drawings, and to the letters and figures marked thereon, that is to
say :-
This Invention relates to rock-drilling machines, in which the drill
rod or plunger is operated by steam or compressed air, and to the mode
of supporting the same, and consists,―
Firstly. In operating the valve on which depends the reciprocating
action of the drill rod directly from the piston by simple mechanism
which will permit the free rotation of the said piston and of the drill rod
which forms a part of the same.
Secondly. In an improved construction of tool holder formed of two
parts or of one part split throughout the greater portion of its length and
confined by bolts and by a ring having a flaring flange for shielding the
stuffing box of the cylinder from the detritus which is discharged from
the hole in which the tool is operating. Also in a peculiar arrangement
of mechanism for imparting a direct movement to the piston rod in a
forward direction, but turning the same during its rearward motion, a
for feeding the entire cylinder and its appliances forward in its ways
with ease when a longer forward movement of the piston than usual is
required by the drilling tool meeting with a crevice in the rock.
and
And, Thirdly. In the construction of a tripod for supporting the
machine, by which it can be readily adjusted to and retained in any
position which the direction of the hole to be drilled may suggest; an
especial feature of this part of the Invention being the ready adjustment
by means of ball-and-socket joints of the legs to such cavities in the
rock as may present themselves.

page_text: And in order that the said Invention may be fully understood I shall
now proceed more particularly to describe the same, and for that purpose
shall refer to the several Figures on the annexed Sheet of Drawings, the
same letters of reference indicating corresponding parts in all the
Figures.
In the perspective view, Figure 1 of the accompanying Drawing,
A represents a portion of the cylinder of a rock-drilling machine, and
midway, or thereabout, between the opposite ends of this cylinder are
the depressed valve seats a and a¹, separated from each other by. an
opening extending from the faces of the valve through to the bore of
the cylinder. In these valve faces are two inlet ports b, b, and two exhaust
ports d, d, the ports of one valve face or seat communicating with one
end of the cylinder and those of the other face or seat with the opposite
end of the cylinder. The usual steam chest for inclosing the valve and
seats, and also the inlet and outlet passages, have been omitted in the
Drawing, for their character will be readly understood by those familiar
with machinery of this class. A valve B of the duplex character (best
observed in the transverse section Figure 2) is so constructed, so adapted
to the seats and ports, and has such a reciprocating motion imparted to
it as to direct steam or compressed air admitted to the chest inclosing
the valve alternately to and exhaust it alternately from the opposite ends
of the cylinder in a manner which will be readily understood without
explanation.
The piston of this cylinder is illustrated in the perspective view,
Figure 3, and consists of two collars e, e, formed on a rod f which
passes through a stuffing box in the cylinder head, and which constitutes
the drill rod for receiving at its outer end the usual boring tool. This
piston must not only be at liberty to reciprocate freely in the cylinder
but must admit of being turned therein, as the requirements of the
boring tool demand; and the main aim of this Invention is to permit
the piston to be rotated freely, and at the same time to cause it to
impart the desired transverse reciprocating motion to the valve. This
is brought about mainly through the intervention of what may be
termed a "sleeve" D, a perspective view of which as it appears when
detached from the piston is shown in Figure 4, the sleeve being in the
present instance made in two parts for ready adjustment to the rod f
to which it is fitted between the collars e, e, so that while it can have
no longitudinal movement independently of the piston, the latter can

page_text: turn freely in the sleeve which has a cam slot x for receiving a central
lug y on the valve, as shown in Figure 2. It is essential however
that the sleeve in order that it may be an effective medium through
which the piston actuates the valve should be prevented from turning.
This is accomplished in the present instance by the frame G (shown in
the perspective view, Figure 5) and consisting of two parallel bars h, h,
'connected together by strips i, i. This frame is adapted to the cylinder,
as shewn in the plan view, Figure 6, the bars h, h, being fitted to the
corners of the recessed valve faces and serving as guides for the valve
and the strips i, i, passing through the opening x in the cylinder, and
projecting into longitudinal slots m, m, formed in the sleeve, as shewn
in Figure 4, so that the said strips prevent the sleeve from turning
without interfering with its longitudinal movement.
It is not essential that the sleeve should entirely surround the piston
rod between the collars e, e. One half D³, Figure 4, for instance, may
be dispensed with, leaving the other portion or plate D to perform the
duties explained above, but it is preferred to use both portions, which
together insure a more uniform wear of the piston.
In the place of the cam slot a groove or ways may be formed in the
'sleeve or its equivalent for acting on the projection y of the valve.
The character of the differential or intermittent reciprocating move-
ment of the valve will depend on the form of the slot or ways of the
sleeve, and the movement of the valve may have to be clianged in
accordance with the character of the blow to be imparted by the drilling
tool, or in accordance with the point in the stroke where it is desirable
to cut off the steam or compressed air, hence it is preferred in all cases
to so make the sleeve that it can be readily removed to make way for a
different sleeve, as in the present instance.
Figure 7 is a longitudinal section of my improved rock drilling
mechanism.
Figure 8, an end view of the tool holder.
Figure 9, an enlarged sectional view of the front part of the
mechanism.
Figure 10, a transverse section on the line 1, 2, looking in the direction
of the arrow 1, Figure 1.
Figure 11. an enlarged view of the rear portion of Figure 1.

page_text: Figure 12, a transverse section on the line 3, 4, looking in the direction
of the arrow 2, Figure 1; and Figure 13, a transverse section on the
line 5, 6, looking in the same direction.
B is the piston rod attached to or forming a part of the piston B¹
adapted to the cylinder A', and at the outer end of the piston rod is the
tool holder c, which is made in two parts, or in one part split throughout
the greater portion of its length, the two parts being secured together
at the front end by bolts, as shewn in Figure 8, so as to embrace the
drilling tool, the tapering rear of the holder being embraced by a ring c¹,
the tightening of which on the tool holder is insured by the striking of
the drilling tool against the rock. The ring c¹ has a flaring flange
which shields the stuffing box of the cylinder from the detritus which is
discharged from the hole in which the tool is operating.
The piston rod B passes through a sleeve A, and has spiral grooves
and ribs corresponding with those in the sleeve.
The forward movement of the piston rod will be in a direct. course,
the sleeve turning and accommodating itself to the rod, but on moving
back the rod must turn owing to the clutch, the stationary portion a¹ of
which is secured within the cylinder A³, the other part a of the clutch
turning with the sleeve and being forced by a spring against the portion
a', so that the inclined teeth of the face of the portion a will slip over
the teeth of the portion a¹ when the piston rod moves forward, but will
engage into the teeth when the piston moves backwards.
The piston B¹ is chambered for the reception of the sleeve b, which
has grooves e adapted to projections on the piston (see transverse
section Figure 12); these grooves being straight throughout the greater
portion of their length, but curved or spiral near their termination.
Under ordinary circumstances the projections f do not reach tho
spiral portions of the grooves, but should the drilling tool reach a crevice
in the rock, and a longer forward movement of the piston than usual
takes place, the projections freaching the grooves will turn the sleeve,
and through the clutch y will turn the nut W of the screw X, and will
consequently feed the entire cylinder and its appliances forward, for the
cylinder is adapted to ways in the frame Y, the latter being secured to
the tripod in the manner hereafter described. The screw is connected
to the frame through the medium of an arm i, and the sleeve b is so

page_text: confined to the cylinder that while it can turn freely it can have no
longitudinal movement, the nut y being also confined in the head of the
cylinder, as shewn in Figure 11, and so combined with a clutchy similar
to that above described and acted on by a spring that the sleeve can turn
in one direction independently of the nut, but must be accompanied
with the latter when turned in the opposite direction.
Figure 14 in the accompanying Drawing represents a perspective view
of the improved tripod comprised under the third part of this Invention..
A, A¹, and B are the three legs for supporting the frame or shell D,
which in the present instance is of a semi-cylindrical form, and has
guides or ways a, a, for receiving projections on the cylinder of the rock-
drilling machine, the latter forming no part of the present Invention.
Each leg of the tripod consists of an external tube of wrought iron,
and an internal rod d so fitted to the tube that it can be turned freely
and adjusted longitudinally therein, and secured after adjustment by a
set screw e passing through a collar or enlargement at the lower end of
the tube, all as shown in enlarged sectional view Figure 15.
-The forked upper end 6 of the rear leg B is adapted to a bolt c which
passes through the cylindrical portion of the frame E (see Figures 16
and 17), the said frame forming the top of the tripod and having two
arms f, to each of which one of the front legs is connected in the manner
best observed in the sectional view, Figure 18, in which f¹ represents a
socket formed on the end of each arm, and adapted to a sphere
The
formed
on or attached to the upper end of the leg A, the said sphero being
confined to its place by a follower i acted on by a screw m, which passes
through a plate n screwed into the said socket. It will thus be scen
that each front leg is connected to the frame E by a ball-and-socket
joint, which permits the leg to be moved in any direction, the joint.
being readily made permanent after adjustment by the screw m.
shell D is connected to the frame E of the tripod in the manner best
observed in the sectional views, Figures 16 and 19. A circular recess p
with an under-cut edge is formed in the under side of the shell, and to
this recess is adapted a circular projection q having a bevilled edge
adapted to the under-cut edge of the projection, one half of the pro-
jection being formed on one portion, and the other on the other of
clamps G, which are arranged to embrace the cylindrical portion g of the
above-mentioned frame E, the two portions of the clamp being connected
together by a bolt hinged to a lip on onc portion, and adapted to a slot.

page_text: in the lip of another portion in a manner too clearly shown in Figure 19
to need explanation. The tightening of the nut of the bolt t expands
the bevilled projection 9 of the clamps against the under cut edges of
the recess p, and thus secures the shell D to the frame E of the tripod,
and the loosening of the nut of the bolt permits such a contraction of
the bevilled projection 9 that it can be withdrawn from the said recess,
or the clamps can be so loosened as to permit the shell D to be turned
laterally to any desired position without detaching it from the tripod,
after which adjustment the shell may be secured by simply tightening
the clamps in the manner described.
Չ
:
The main feature of this Invention however is the attachment of the
front legs of the tripod to its frame by means of ball-and-socket joints,
for these joints permit the ready adjustment of the lower pointed ends
of the legs to any cavity in the rock which may be present to afford a
secure lodgement for the said pointed ends of the legs. After the tripod,
for instance, has been placed in the position determined by the direction
in which the hole has to be bored, it may be found that one of the legs.
has not a secure lodgment, in which case it may be adjusted to any
neighboring cavity without any change in the position of the frame or
shell D, for the leg may be elongated or contracted in accordance with
its position as determined by the cavity. This adjustment of the tripod
may be in a measure effected by connecting one of its legs only to the
frame with a ball-and-socket joint, or all the legs may be thus connected
to the frame, but it is found best in practice to confine these joints to the
two front legs, as shown in the Drawing and as described above.
In many cases it is necessary to so adjust a rock drill that it will
bore holes near the ground, hence the adjustable rod d of each leg is
provided with an adjustable spur I, so that the legs may be outstretched
to permit the depression of the shell D, as shown in Figure 19, in
which case the said spurs are adjusted to cavities in the rock, as shown.
It is necessary when the rock drill is in operation that the tripod
should be weighted, for which purpose each leg is furnished with a
hooked projection w adapted to a recess in a weight m', as shown in
Figure 20, the said weight having a groove for receiving, and being
steadied laterally by the leg from which the weight can be readily.
detached.

page_text: It will be seen without further description that the shell D, and con-
sequently the drilling machine attached to it, can be vibrated freely on
the cylindrical portion E of the frame F, and can be turned laterally on
the bevilled projection 2 of the clamps G, while the legs afford ample
opportunities for the vertical adjustment of the shell D.
Having now described and particularly ascertained the nature of the
said Invention, and the manner in which the same is or may be used or
carried into effect, I would observe in conclusion that what I consider to
be novel and original, and therefore claim as the Invention secured to
me by the herein-before in part recited Letters Patent is,-
First. The combination of a transverse valve with the cylinder and
piston of a rock-drilling machine, substantially as hercin-before described
and illustrated by Figures 1 to 6 of the accompanying Drawings.
Second. The combination of the cylinder and piston of a rock-drilling
machine with a transverse valve operated from the said piston through
the medium of a cam slot or ways on a sleeve or plate, which is carried
by and reciprocates but cannot turn with the piston, substantially as
herein-before described and illustrated by Figures 1 to 6 of the accom-
panying Drawings.
Third. The arrangement of sleeve made in two parts D and D¹ adapted
to cach other and to the piston, substantially as and for the purpose
herein-before described and illustrated by Figures 2, 3, and 4 on the
accompanying Drawings.
Fourth. The construction and arrangement of the frame G adapted to
the transverse valve, the cylinder piston, and sleeve, substantially as and 2
for the purpose herein-before described and illustrated by Figures 1 to 6
of the accompanying Drawings.
Fifth. The construction and arrangement of the tool holder c con-
sisting of two parts, or of one part split throughout the greater portion
of its length and confined by bolts and by a ring c¹ adapted to the a
tapering part of the holder, substantially as and for the purpose herein-
before described and illustrated by Figures 7 and 8 on the accompanying
Drawings.
Sixth. The construction of the flaring flange on the tool holder, sub-
stantially as and for the purpose herein-before described and illustrated 3
by Figures 7 and 8 of the accompanying Drawings.

page_text: the leg, substantially as and for the purpose herein-before described and
illustrated by Figures 14 and 20 on the accompanying Drawings.
In witness whereof, I, the said John Henry Johnson, have to this my
Specification set my hand and seal, this Fifth day of November,
One thousand eight hundred and seventy-four.