IMPROVEMENTS IN APPARATUS FOR MINING COAL
Year: 1883

page_text: LETTERS PATENT to William Robert Lake, of the firm of Haseltine Lake
& Co Patent Agents, Southampton Buildings London for an Invention of
"IMPROVEMENTS IN APPARATUS FOR MINING COAL" communicated to him
from abroad by Benjamin Franklin Asper, of Pittsburgh, Pennsylvania,
United States of America Mechanical Engineer
-
PROVISIONAL SPECIFICATION' left by the said William Robert Lake at the
Office of the Commissioners of Patents on the 4th December 1883.
WILLIAM ROBERT LAKE, of the firm of Haseltine, Lake and C° Patent Agents,
Southampton Buildings, London, "IMPROVEMENTS IN APPARATUS FOR MINING
COAL "
[A communication to bin from abroad by Benjamin Franklin Asper, of
Pittsburgh Pennsylvania, United States of America Mechanical Engineer.]
.
This invention relates to apparatus for cutting or mining coal, and has for its
object to greatly facilitate the operation and thereby reduce the expense of mining
coal, by the substitution for the ordinary and tedious manual labor, of automatic
machinery actuated by steam or other equivalent motive power.
The said invention consists in the novel construction and arrangement of parts
and comprises a series of reciprocating picks or digging implements, the strokes of
which are produced by the contraction of powerful springs, which are distended
through the medium of a motor shaft carrying tappet arms for such purpose;
mechanism for feeding the said picks forward as the channelling progresses, the said
mechanism comprising a peculiar combination of right and left hand screws, one of
which is attached to the main frame or carriage while the other is connected to the
pick frame and telescoped within the former in such a manner that it will reciprocate
with the frame while being caused to rotate with the outer screw; means whereby
the picks may be adjusted relatively to accommodate themselves to any condition
of obliquity in the vein or mine; means for giving the carriage or main frame a
lateral feeding movement on its base, such movement being obtained by suitable
intermediate bearing from the motor shaft causing the picks to travel laterally the
width of the channel being cut, such travel being continuously to and fro, so that
the mining proceeds in both directions, that is from left to right and right to left

page_text: alternately cleaning chains which clean out and empty the channel as the work
proceeds, such chains being arranged to feed forward and laterally with the
respective picks; devices whereby the machines may be adjusted to any pitch or
inclination, according to the nature of the coal vein; and various details of
construction pertaining to devices whereby the aim and object of the invention
may be fully accomplished.
In carrying the said invention into practice I provide a rectangular frame or bed
upon the end of which are mounted the moving parts of the apparatus. The said
frame comprises side bars, end pieces, and intermediate ties. Upon the end pieces
are formed grooves or ways which receive the end bars of the carriage, the latter
being designed and adapted to travel laterally thereon.
The bed is supported at its corners upon casters, fitted to threaded standards,
which screw into suitable screw sockets, the bed may be adjusted by means of
screws to any height, pitch, or inclination required by the peculiar form or other
conditions of the vein, or the locality of the channel to be cut.
The carriage is a wrought or cast iron structure of rectangular form. The side
bars are slotted for the reception of the transverse bars of the pick-frame.
The said picks consist of heads of wedge or chisel form, or they may be of any
shape found best adapted to their functions. These heads are mounted on the ends
of long bars fitting in the head sockets and fastened by set screws, by loosening
which the heads may be removed.
The said long bars extend completely through the carriage and beyond the ends,
which have holes for their passage and play.
The transverse bars constituting the pick frame, are arranged to slide on the
floors of slots in the sides of the carriage, and are held together and braced by bolt
bars, threaded on their ends and secured by nuts.
The pick rods pass loosely through one of the said bars relatively to which the
other bars are adjustable through the medium of the feeding screws, but are
fastened to the first bar by means of set screws; and clamp collars abut against the
forward side of the first bar, and are preferably made in two semi-cylindrical
sections hinged together, and interlocked by set screws which secure them to the
pick rods.
The object of the clamp collars is to provide a more secure fastening between the
bar and the pick-rods, and they are made in two sections to enable them to
be removed and replaced without difficulty.
The stroke of the pick forward is effected by powerful coiled springs located
between, and secured at their ends to, the forward end of the carriage and one of
the bars.
When the pick frame is retracted, the springs are distended, and when released
the springs forcibly contract, thus driving the picks forward with a force
commensurate only with the power and tension of the springs. The retraction
of the pick frame with the picks is accomplished by the agency of the motor shaft
driven by some suitable motor such as a steam, gas, or other engine.
The motor shaft is mounted upon, and transversely of, the carriage, in suitable
bearings and coupled in any desirable manner with the engine or motor, so as to
obtain therefrom a continuous rotary motion.
Upon this shaft are mounted collars having radial tappet arms carrying anti-
friction rollers on their ends. As the shaft rotates these arms, through their rollers,
come successively in contact with rollers firmly sustained upon one of the bars by
standards, and in the act of impinging against, or of passing the said rollers force
the pick-frame back. As soon as released the frame is projected forward and the
result is a rapid reciprocating action of the pick frame and picks, the stroke
occurring between each period of contact of the tappet arms and pick-frame.
The lateral feed of the picks is accomplished in the following manner, that is
to say
To the intermediate ties are secured toothed racks with which engage pinions
mounted on a horizontal shaft having its bearings in a frame. One of the said

page_text: pinions gears with a spur wheel mounted in the said frame and carries on its shaft
opposing bevelled gear wheels with which engage alternately the teeth of a
mutilated bevelled gear wheel. The said mutilated gear wheel is mounted on the
same shaft with a worm wheel engaging with a worm which is turned from the
main shaft through bevelled gearing. Now, as the shaft turns and the picks
operate, the gearing above described causes the carriage to travel slowly in a lateral
direction, so that the picks will cut a horizontal channel in the coal of a width
corresponding to the length of the rack on the bed and the semi-circumference of
the mutilated wheel. The parts are so proportioned that the picks shall travel the
distance between the adjacent picks one pick reaching the point where the next
adjacent pick began. When such point is reached, the picks are led forward and
the carriage begins to travel in a reverse direction. This reversal is effected under
the continuous rotary motion of the main shaft by the conjoint action of the,
mutilated wheel and one of the opposing pinions, for as soon as the teeth of said
wheel leave the pinion which turns the shaft in a direction necessary for the travel
of the carriage as first described, they immediately engage with another pinion, and
cause a reverse movement. Thus the carriage travels to and fro continuously and
the picks require no attention other than the regulation and control of their forward
feed as the sides of the channel are alternately reached. Now while the machine
is primarily designed to operate with all the picks which its construction will
accommodate, yet as the picks, although attached to the one frame, are otherwise
independent of each other, any number may be employed less than the full rank,
those not required being displaced from the pick frame, and only those operated
that are required or expedient to use according to the work to be done.
Again the picks are susceptible of relative or independent, adjustment, by moving
and setting the pick rods in the pick frame, so that they will operate in a right
line, or at any degree of obliquity or irregularity required by the varying conditions
of the vein, or the form of the mining shaft, thus rendering the machine available
under all circumstances, and even capable of use when manual labor would be
impossible, inexpedient, or unsafe.
To feed the picks forward to their work I employ the following means that is to
say a hollow or tubular screw is located in the rear half of the carriage with its
bearings in the end thereof, and the frame.
Upon the rear end of this screw is a toothed pinion driven by a toothed wheel
having sprockets or arms and journalled to the carriage. This hollow screw passes
through and carries a cross head to which are attached clearing rods, and when the
said screw is turned the cross head moves thereon, carrying with it, forward or
backward according to the direction of revolution, the said chain rods.
A second screw is threaded reversely to the hollow screw and is fitted within, or
telescoped into, the said hollow screw and is also tubular, its bore being squared to
receive a square rod, which is attached at its rear end to a pinion so as to turn
therewith and with the second screw. The telescoping arrangement of the two
screws and the square rod is employed in order to give the requisite feeding move-
ment, and at the same time allow the second screw to reciprocate freely within,
and independently of, the hollow screw and upon the rod. The second screw is
journalled at its forward end in the first bar of the pick frame, and passes through
a threaded opening in one of the other bars. Now as the hollow screw is turned in
the direction necessary for feeding the picks to their work, the cross head is forced
forward with the chain rods and the chains. At the same time the second screw,
turning in its threaded socket in the bar, is bodily moved forward, forcing before it
the bars, and pick frame, and with the same uniform movement, as the chain bars
and chains, thus preserving the relation of the chains and picks, and keeping them
in line. This capability of the second screw of thus being moved forward does not
interfere with the play of the pick frame, as while the latter reciprocates, the second
screw moves freely within the hollow screw and upon the rod.
The chains are carried upon, and over, sprocket wheels or rollers upon the ends

page_text: of the chain rods and are propelled by sprocket wheels mounted upon the main
shaft. Slots are provided in the ends of the carriage for the passage of the chain.
The chain projects to nearly a line with the ends of the picks so as to enter the
channel formed thereby and clear out the cuttings as they are cut. To facilitate
cleaning, the chain may be provided with scrapers located at proper intervals. The
sprocket wheels or rollers are mounted in the forked ends of sockets or ferrules
secured to the ends of the chain rods by set screws and capable of adjustment so as
to take up slack in the chains.
In order to avoid any tendency in the first bar to become strained or bent owing
to the screw connection therewith being in the middle part of the bar, and working
against the resistance of the pick rods, or either side thereof, I provide a device
which consists of a pair of rack bars secured by nuts on their threaded ends to the
cross bars and passing under or through slots in one of the bars, which bar carries
dogs engaging with the teeth of the said rack in one direction only.
These rack bars and dogs serve to brace and strengthen the first bar against the
thrust of the screw, the rack resisting the counter tendency of the ends of the bars.
The feeding action of the pick frame is in no wise interfered with by the rack and
dog device as the dog rides freely over the teeth, as the frame moves forward.
I also provide a device which may be employed when it is desired to rotate the
main shaft by hand instead of steam or other equivalent power. This device
consists of a lever fulcrummed upon a standard and provided with spring dogs
engaging with a ratchet wheel mounted on the main shaft. When the lever is
raised the dog engages the wheel and turns it the distance of a tooth, and by several
movements the pick springs are distended sufficiently for striking purposes. A
detent is attached to the standard and serves to hold the ratchet wheel at any
desired position.
A form of pick head which is very serviceable is forked, this forked construction
adapting it to dig closely at the ends of the channels as well as to cut shorter
channels than could well be formed when pointed picks are used.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Robert Lake in the Patent Office on the 4th June 1884.
WILLIAM ROBERT LAKE of the firm of Haseltine, Lake & Co, Patent Agents,
Southampton Buildings London "IMPROVEMENTS IN APPARATUS FOR MINING
COAL "A communication to me from abroad by Benjamin Franklin Asper, of
Pittsburgh, Pennsylvania, United States of America, Mechanical Engineer
This invention relates to apparatus for cutting or mining coal, and has for its
object to greatly.facilitate the operation and thereby reduce the expense of mining
coal, by the substitution, for the ordinary and tedious manual labor, of automatic
machinery actuated by steam or other equivalent motive power.
The said invention consists in the novel construction and arrangement of parts,
and comprises a series of reciprocating picks or digging implements, the strokes of
which are produced by the contraction of powerful springs, which are distended
through the medium of a motor shaft carrying tappet arms for such purpose;
mechanism for feeding the said picks forward as the channelling progresses, the
said mechanism comprising a peculiar combination of right and left hand screws,
one of which is attached to the main frame or carriage, while the other is connected
to the pick frame and telescoped within the former in such a manner that it will
reciprocate with the frame while being caused to rotate with the outer screw;
means whereby the picks may be adjusted relatively to accommodate themselves to
any condition of obliquity in the vein or mine; means for giving the carriage or
main frame a lateral feeding movement on its base, such movement being obtained
by a suitable intermediate bearing, from the motor shaft, causing the picks to
travel laterally the width of the channel being cut, such travel being continuously
to and fro, so that the mining proceeds in both directions, that is, from left to right
and right to left alternately; cleaning chains which clean out and empty the
channel as the work proceeds, such chains being arranged to feed forward and
laterally with the respective picks; devices whereby the machines may be adjusted.
to any pitch or inclination, according to the nature of the coal vein; and various
details of construction pertaining to devices whereby the aim and object of the
invention may be fully accomplished.
'
In the accompanying drawing
Figure 1 is a plan or top view of a mining machine constructed according to this
invention
Figure 2 is a central longitudinal section of same
Figures 3, 4, 5, 6, 7, 8 and 9 are views of details
A indicates a rectangular frame or bed upon which are mounted the moving parts
of the apparatus. The said frame comprises the side bars a the end pieces a¹ and
the intermediate ties a³, a³. Upon the end pieces a' are formed grooves or ways at
which receive the end bars of the carriage B, the latter being designed and adapted
to travel laterally thereon.
The bed A is supported at its corners upon casters b, fitted to threaded
standards b¹ which screw into suitable screw sockets, and may be adjusted by
means of screws v to any height, pitch or inclination required by the peculiar form
or other conditions of the vein, or the locality of the channel to be cut
The carriage is a wrought or cast iron structure of rectangular form having the
sides B¹ and ends B². The side bars are slotted at 63, as shown, for the reception
of the transverse bars of the pick frame.
CC indicate the picks consisting of the heads c of wedge or chisel form, or they
may be of any. shape found best adapted to their functions. These heads are,

page_text: mounted on the ends of long bars D fitting in the head sockets d and are fastened
by set screws d³, by loosening which the heads may be removed.
The bars D extend completely through the carriage and beyond the ends, which
have holes d for their passage and play.
E, E¹ E' indicate transverse bars constituting the pick frame, which bars are
arranged to slide on the floors of the slots 6s in the sides of the carriage. The
bars E E' are held together and braced by the bolt bars e, e¹, threaded on their
ends and secured by nuts e³, e³.
The pick rods pass loosely through the bar E', relatively to which the bars E, E¹
are adjustable through the medium of the feeding screws, but are fastened to the
bar E' by means of set screws e³, es. Clamp collars e abut against the forward
side of the bar E and are preferably made in two semi-cylindrical sections hinged
together, and interlocked by set screws e" which secure them to the pick-rods.
The object of the clamp collars is to provide a more secure fastening between
the bar E¹ and the pick rods, and they are made in two sections to enable them to
be removed and replaced without difficulty.
The stroke of the pick forward is effected by powerful coiled springs F, F,
located between, and secured at their ends to, the forward end of the carriage and
the bar E.
When the pick frame is retracted, the springs are distended, and when released
the springs forcibly contract, thus driving the picks forward with a force com-
mensurate only with the power and tension of the springs. The retraction of the
pick frame with the picks is accomplished through the agency of the motor shaft
driven by some suitable motor such as a steam, gas or other engine.
G indicates the motor shaft mounted upon and transversely of, the carriage in
suitable bearings g, g, and coupled in any desirable manner with the engine or
motor, so as to obtain therefrom a continuous rotary motion.
Upon this shaft are mounted the collars H having the radial tappet arms h
carrying anti-friction rollers h¹, on their ends. As the shaft rotates these arms,
through their rollers come successively in contact with rollers he firmly sustained
upon the bar E by standards h³, and in the act of impinging against or of passing
the said rollers ha force the pick-frame back. As soon as released the frame is
projected forward, and the result is a rapid reciprocating action of the pick-frame
and picks, the stroke occurring between each period of contact of the tappet arms
and pick-frame.
The lateral feed of the picks is accomplished in the following manner, that is to
say-To the cross bars a², a³ are secured the tooth racks I, II with which engage
the pinions I I³ mounted on a horizontal shaft I having its bearings in the
frame K K¹. The pinion I² gears with a spur wheel L mounted in the frame K,
and carries on its shaft L' the opposing bevelled gear wheels l, l' with which
engages alternately the teeth of a mutilated bevelled gear wheel m. The wheel m
is mounted on the same shaft with a worm wheel m³, engaging with a worm m²,
which is turned from the main shaft through the bevelled gearing m³ m². Now
as the shaft turns and the picks operate, the gearing above described causes the
carriage to travel slowly, in a lateral direction, so that the picks will cut a hori-
zontal channel in the coal, of a width corresponding to the length of the rack on
the bed and the semi-circumference of the mutilated wheel. The parts are so
proportioned that the picks shall travel the distance between the adjacent picks,
one pick reaching the point where the next adjacent pick began. When such point
is reached, the picks are led forward and the carriage begins to travel in a reverse
direction. This reversal is effected under the continuous rotary motion of the main
shaft, by the conjoint action of the mutilated wheel and one of the opposing
pinions, for as soon as the teeth of said wheel leave the pinion which turns the
shaft L' in a direction necessary for the travel of the carriage as first described,
they immediately engage with the pinion , and cause a reverse movement. Thus
the carriage travels to and fro, continuously, and the picks require no attention
other than the regulation and control of their forward feed as the sides of the

page_text: channel are alternately reached. Now while the machine is primarily designed to
operate with all the picks which its construction will accommodate, yet, as the
picks although attached to the one frame are otherwise independent of each other,
any number may be employed less than the full rank, those not required being
displaced from the pick frame, and only those operated that are required or
expedient to use according to the work to be done.
Again the picks are susceptible of relative or independent adjustment, by
moving and setting the pick rods in the pick frame, so that they will operate in a
right line or at any degree of obliquity, or irregularity, required by the varying
conditions of the vein, or the form of the mining shaft, thus rendering the machine
available under all circumstances, and even capable of use when manual labor
would be impossible, inexpedient or unsafe.
To feed the picks forward to their work, I employ the following means.
A hollow or tubular screw N is located in the rear half of the carriage, with its
bearings in the end thereof and the frame K. Upon the rear end of this screw is
a toothed pinion n driven by a toothed wheel n¹ having sprockets or arms n³ and
journalled to the carriage. This screw passes through and carries a cross head O
to which are attached the clearing rods O¹ and when the screw is turned the cross
head moves thereon, carrying with it, forward or backward, according to the
direction of revolution, the said chain rods.
P indicates a second screw which is threaded reversely to the screw N, and
fitted or telescoped therein. The screw P is also tubular, its bore being squared
to receive a square rod N¹ which is attached at its rear end to the pinion n so as.
to turn therewith and with the screw P. The telescoping arrangement of the two
screws and the square rod is employed in order to give the requisite feeding
movement, and at the same time allow the screw P to reciprocate freely within
and independently of, the screw N and upon the rod. The screw P is journalled
at its forward end in the bar E¹ of the pick frame, and passes through a threaded
opening in the bar E'. Now as the screw N is turned in the direction necessary
for feeding the picks to their work, the cross head O is forced forward with the
chain rods and the chains. At the same time the screw P turning in its threaded
socket in the bar E' is bodily moved forward, forcing before it the bars E, E' and
pick frame, and with the same uniform movement as the chain bars, and chains,
thus preserving the relation of the chains and picks, and keeping them in line.
This capability in the screw P of thus being moved forward does not interfere
with the play of the pick frame, as while the latter reciprocates the screw P moves
freely within the screw N and upon the rod N¹
The chains 0, 0³ are carried upon and over sprocket wheels or rollers g' g' upon
the ends of the chain rods, and are propelled by sprocket wheels 98 9₁ mounted
upon the main shaft, Slots R, R, are provided in the ends of the carriage for the
passage of the chain.
The chain projects to nearly a line with the ends of the picks so as to enter the
channel formed thereby and clear out the cuttings as they are cut. To facilitate
cleaning, the chain may be provided with scrapers R₁ located at proper intervals.
The sprocket wheels or rollers g¹, g₁ are mounted in the forked ends of sockets or
ferrules R R2, secured to the ends of the chain rods by set screws and capable of
adjustment, so as to take up slack in the chains.
.
In Figure 6 I have shewn an expedient, whereby I avoid any tendency in the
bar E to become strained or bent owing to the screw connection therewith being
in the middle part of the bar, and working against the resistance of the pick rods
or either side thereof. Such expedient consists of a pair of rack bars e¹ secured by
nuts on their threaded ends to the cross bars E, E³, and passing under or through
slots in the bars E¹ which bar carries dogs S¹, S¹ engaging with the teeth of the
said rack in one direction only. These rack bars and dogs serve to brace and
strengthen the bars E against the thrust of the screw, the rack resisting the counter
tendency of the ends of the bars. The feeding action of the pick frame is in no

page_text: wise interfered with by the rack and dog device as the dog rides freely over the
teeth, as the frame moves forward.
In Figure 7 is shewn a device which may be employed when it is desired to
rotate the main shaft by hand instead of steam or other equivalent power. This
device consists of a lever T fulcrummed upon a standard T¹, and provided with
spring dogs t and t engaging with a ratchet wheel T' mounted on the main shaft.
When the lever is raised the dog engages the wheel and turns it the distance of a
tooth, and by several movements the pick springs are distended sufficiently for
striking purposes.
U indicates a detent attached to the standard T¹, and serving
to hold the ratchet wheel T2 at any desired position.
Figure 8 shows a form of pick head which is very serviceable, its forked
construction adapting it to digging closely at the ends of the channels as well as to
cut shorter channels than could well be formed when the picks shown in Figures 1
and 2 are used
Having thus fully described the said invention as communicated to me by my
foreign Correspondent and the manner of performing the same I wish it understood
that I Claim In apparatus for mining coal
First A series of horizontally reciprocating picks, a reciprocating frame to which
the said picks are attached, and in which they are adjustable by means of a cross
head attached to them and its operating screws, a motor shaft with tappets and
connections for retracting the said frame, and springs arranged substantially as
described so as to be distended when the frame recedes, and to alternately contract
and project or drive the frame forward, as set forth
Second. The combination with the reciprocating pick frame E E¹ E³, and the
feeding screw P attached to the bar E' and working through a nut or bar E2, of the
rack bars e el coupling the bars E E², and the dogs S¹ pivotted upon the bar E¹,
substantially as, and for the purpose, set forth.
Third. A laterally moving carriage carrying picks which reciprocate therein, in
combination with bevelled pinions which face each other upon their shaft, suitable
gearing connecting the said shaft with the laterally moving carriage, a mutilated
gear wheel which engages with the said bevelled pinions, alternately, and suitable
gearing connecting the said mutilated gear wheel with the driving shaft, substantially:
as described
Fourth. A laterally moving carriage carrying picks which reciprocate therein
and are attached to a reciprocating frame, in combination with a driving shaft
carrying tappets through which the frame is retracted, bevelled pinions which face
each other upon their shaft, suitable gearing connecting the said shaft with the
lateral moving carriage, a mutilated gear wheel which engages with the said
bevelled pinions alternately, and suitable gearing connecting the said mutilated.
gear wheel, with the driving shaft, substantially as described and for the purpose
set forth.
Fifth. The combination of the supporting fraine A, a laterally moving carriage
thereon carrying the reciprocating picks C and the driving shaft G, the worm m².
driven from the said shaft by suitable gearing, the worm wheel m' engaging with
the said worm, the mutilated bevel gear wheel m upon the shaft of the said worm
wheel, the bevel pinions i i'upon the shaft L' arranged to be alternately engaged by
the said mutilated gear wheel, the spur wheel L on the shaft L1, and the pinions.
12 13 driven by the said wheel L and engaging with the racks I I¹ upon the
frame a, whereby the said carriage is fed laterally across the face of the coal and
alternately reversed and fed back again, substantially as described
Sixth. The combination of the reciprocating pick frame composed of the bars
E E and connecting rods e e¹, the picks mounted in the said frame, the cross-
head E¹ secured to the said picks, and the screw P swivelled in the said cross-head.
and engaging a nut fixed in the cross bar E2, whereby the said picks may be.
adjusted longitudinally with respect to the pick frame, substantially as described...
Seventh. The combination of the reciprocating pick. frame, the picks C loosely:

page_text: mounted therein, the adjusting screw P swivelled to the cross-bar E' of the said
frame (which cross-bar is secured to the pick rods) and engaging with a nut in the
cross bar E, and the square revolving rod N¹ entering a square hole in the said
screw, whereby the latter can be revolved without interfering with the reciprocation
of the frame, substantially as described
Eighth. The combination of the hollow adjusting screw N, the cross head O
carrying the chain supporting rods operated thereby, the clearing chains running
over the said rods, the reciprocating pick frames and picks mounted therein, the
hollow screw P connected to the said frame for adjusting the picks the said screw
reciprocating within the screw N, and means for revolving the said screws,
substantially as described
Ninth. The combination of the reciprocating picks made longitudinally
adjustable with respect to the reciprocating mechanism, and clearing chains
arranged parallel thereto and running in longitudinally adjustable supports,
substantially as described.
Tenth. The combination of the cross-head O, the screw N for advancing the
same, the chain rods 02 attached thereto, the clearing chains running over pulleys
mounted on the said rods, and mechanism for operating the said chains,
substantially as described
Eleventh. The combination with a reciprocating frame carrying the picks C, and
mechanism, substantially as described, for actuating the said picks, of the hollow
screw N journalled in the carriage B B¹ B2, the square rod N₁ coupled to the said
screw, and the hollow screw P reciprocating in the screw N and upon rod N¹, said
screw P being connected to the pick frame and the said screw N being connected to
a cross head carrying the clearing chain rods, substantially as described, so as to
feed the picks and the clearing chains forward, as set forth.
In witness. whereof I the said William Robert Lake have hereunto set my hand
and seal this Thirtieth day of May in the year of Our Lord One thousand eight
hundred and eighty four.