IMPROVEMENTS IN CUTTING WOOD AND OTHER SUBSTANCES, AND IN THE MACHINERY OR APPARATUS EMPLOYED THEREIN, AND IN THE APPLICATION OF POWER TO THE SAME, PARTS OF WHICH IMPROVEMENTS ARE APPLICABLE TO THE TRANSMISSION OF POWER GENERALLY
Year: 1852

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
MCDOWALL, of Walkinshaw Foundry, Johnstone, in the County of Renfrew,
North Britain, Engineer, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent, under the Great Seal of the United Kingdom of Great"
Britain and Ireland, bearing date at Westminster, the Twentieth day of
March, in the fifteenth year of Her reign, did, for Herself, Her heirs and
successors, give and grant unto me, the said John McDowall, Her especial
licence, full power, sole privilege and authority, that I, the said John
McDowall, my exors, adñors, and assigns; and such others as I, the said
John McDowall, my exors, adñiors, or assigns, should at any time agree
with and no others, from time to time and at all times during the term
of years therein mentioned, should and lawfully might make, use, exercise,
and vend, within England, Wales, and the Town of Berwick-upon-Tweed,
and also within the Islands of Jersey, Guernsey, Alderney, Sark, and Man,
and in all Her Majesty's Colonies and Plantations abroad, my Invention
of "IMPROVEMENTS IN CUTTING WOOD AND OTHER SUBSTANCES, AND IN THE MACHINERY
OR APPARATUS EMPLOYED THEREIN, AND IN THE APPLICATION OF POWER TO THE SAME,
PARTS OF WHICH IMPROVEMENTS ARE APPLICABLE TO THE TRANSMISSION OF POWER
GENERALLY;" in which said Letters Patent is contained a proviso, obliging me,
the said John McDowall, by an instrument in writing under my hand and
seal, particularly to describe and ascertain the nature of my said Invention,
and in what manner the same is to be performed, and to cause the same to
be enrolled in Her Majesty's High Court of Chancery within six calendar

page_text: months next and immediately after the date of the said in part recited
Letters Patent.
NOW KNOW YE, that, in compliance with the said proviso, I, the said
John McDowall, do hereby declare the nature of my Invention, and in
what manner the same is to be performed, to be particularly described and
ascertained in and by this present Instrument in writing as follows, reference
being had to the accompanying Drawings, and to the letters and figures
marked thereon, that is to say:-
My said Invention relates to various arrangements of mechanism, apparatus,
or means for cutting up or sawing timber or other convertible materials in a
more economical, speedy, and accurate manner than by the machinery or
modes hitherto in use. And in order that my said Invention may be properly
understood, I shall now proceed to describe the several Figures on the Sheets
of Drawings hereunto attached.
Figure 1, on Sheet 1 of my Drawings, is a complete front elevation of one
modification of my improved sawing machinery on my duplex plan, that is,
with two separate saws, one on each side of the main frame.
Figure 2 is a corresponding side elevation of the same machine at right
angles to Figure 1, looking on the edges of the saws with the timber being
cut in end elevation.
Figure 3 is a similar elevation, partly in section, shewing the details of the
feed and adjustable fence apparatus.
Figure 4 is a plan of the saw guides and tension apparatus detached.
Figure 5 is a side elevation of my adjustable saw buckle in detail on a
larger scale;
And Figure 6 is a corresponding edge view of the same.
The leading essential feature of my Invention has reference to the so
arranging sawing machinery that an effective amount of tension may be given
to the saw without the necessity of using the ordinary heavy saw frame and
buckles, whilst the machine may be driven at a much higher velocity than is
usual at present, and the "rake" or "overhang" of the saw easily and
accurately adjusted to suit the amount of feed given to the timber. By the
existing mode of procedure a whole log or baulk is usually cut up into
planks or boards at once, a heavy frame being used with as many saws
Loss frequently
set on it as shall give the required number of cuts.
occurs from this system by reason of the impossibility of judging from
external appearances as to the actual state of the heart of the log, so that
a number of boards are frequently lost in the centre, owing to the log being
It is therefore desirable that the log
spungy or unsound at the heart.

page_text: should first be opened up the centre, in order to shew how the wood is and to
enable the sawyer to cut it up in such way as will best economise the
material, laying the flat side against a fence. But this single cut cannot be
economically effected with the existing machinery, as loss would arise from
working a single saw at the present slow rate which the heavy saw frame
revolves. According to my Invention, then, I purpose to work in most cases
with a single saw, driving it at such increased rate of speed as will enable me to
perform as much or nearly as much work as when using a series or frame full
of saws, whilst the machinery is exceedingly manageable, and may be readily
adjusted or altered to suit various purposes. The main framing A, of my
machines, consist of a pair of strong cast iron columns, connected together by
a cross beam and surmounted by an entabulature, and carried upon a base or
foundation plate B. It is actuated by the main horizontal shaft C, carrying
fast and loose strap pulleys D, receiving motion in the usual way. This shaft
is passed through the space intervening between the cross beam of the framing
and the entablature, being carried in bearings E, E, in the upper portion of the
framing pillars, and having fast upon it two strong metal dises or fly wheels F,
the one at the overhanging end of the shaft being employed to communicate
motion to the saws by a pin G upon its face, acting like a common crank pin.
To this pin is jointed a connecting rod H, which is again jointed at its lower
end to the pin I of the longer crank lever J, fast on one end of the bottom
horizontal shaft K, which is carried in bearings at L, in the bases of the pillars.
Then as the crank pin G above constantly revolves, it gives a continuous reci-
procatory motion to the longer lever J, and bottom shaft K. This shaft has
keyed upon its centre a broad strap pulley M, to the periphery of which is
fixed by its longitudinal centre a band of leather or thin flexible steel or other
material N, the two ends of which hang loose, and are respectively connected
at O, O, by buckles or coupling joints on each side to the lower ends of the
two opposite parallel saws P, P. The upper ends of these saws are attached
by what I term my adjustable buckles at Q, Q, to a flexible strap or link
piece R, passed over and attached to the corresponding overhead pulley S,
just as in the arrangement beneath. The pulley S is fast upon a short shaft
T, working in bearings in the upper end of the vertical adjustable slide
frame U, by which the tension of the same is adjusted. This slide is fitted to
work up and down on the inside and edge faces of the fixed frame V, which
is bolted by its base to the surface of the entablature of the main frame.
The lower shaft K and pulley M being held in fixed bearings, the tensional
adjustment is given entirely from above by means of the vertical screw. W,
passed through the entablature on which it rests by a collar X, fiting into a

page_text: slight recess, the upper screwed end being entered into a nut Y, fast in the
bottom of the sliding frame U. The portion of the screw spindle beneath the
collar X is plain and projects through the entablature, beneath which it has
fast upon it a spur wheel Z, in gear with a pinion a, fast on the upper end of
a vertical shaft b. The upper end of this shaft is carried in a collar bearing c,
on the side of the main frame, whilst its lower end is supported in the cross
slide framing beneath. This gearing and screw is actuated by a handle d, on
the projecting end of the horizontal shaft e, which is connected at its opposite
end of the pair of bevil pinions f to the shaft b, so that by turning the
handle d in either direction, any required tension may be given to the pair of
saws by the corresponding vertical traverse of the frame U, when acted on by
the adjusting screw. Thus, when the requisite degree of tension has been given
to the pair of saws, the rapid revolution of the shaft C causes the two pulleys M
and S to work in a continuous series of reciprocating partial revolutions, work-
ing the two saws alternately up and down in their vertical plane at a rapid
rate for sawing. In order to guide the saws in an accurate vertical line,
upper and lower guides are set on each side the main framing. The upper
guides are sustained by the bracket g bolted to one side of the fixed standard
or frame V, two curved arms projecting out, one on each side, and terminating
in vertical guides h, with V groove faces to receive the small slides i, attached
to the buckles. The lower ends of these guides are steadied by the cross beam
of the main framing, angular legs or bent bracket pieces ; being cast on them
for bolting by a long bolt k, passed through two short tubular pieces b, set one
on each side the cross beam through which the bolt also passes, a nut at each
end of the bolt affording the power of screwing up the guides to a firm bearing
against the collars of the tubular pieces. On the back of each of these guides
there is groove, in which a small slide piece M is fitted to set up or down,
being adjustable by a bolt passed through both pieces. At the lower end of
the piece M a forked piece of metal N is jointed to it stiffly by a tightening
nut, the forked or slit portion being fitted to receive or embrace the saw and
steady it laterally during working, whilst its adjustable slide admits of its
being raised or lowered to suit the various thicknesses of wood to be sawed,
so that the steadying resistance may always be brought as near to the point
of greatest strain or vibration as possible. To steady the saw beneath, an
adjustable piece O is fixed to each edge of the loose plates set on the top of
the cross slide framing where the wood is carried, so that these pieces, being
set up towards each other, embrace the saw between them.
guides p are precisely similar to the upper ones, except that they are bolted by
bottom flanges to the surface of the foundation plate. In my Drawings I
The lower

page_text: have represented one of the saws as cutting up a "log" through the centre,
and the other sawing a "deal." The timber with the traverse apparatus and
fence and feed rollers are carried on separate framings supported by the four
short pillars, the rectangular entablature or table of which is set transversely
in relation to the main framing and between the pillars A. It is steadied by
flanges r bolted to blank flanges cast on the insides of the pillars A, and is
fitted upon one side like the slide rest of a lathe, angular or dovetail fittings
being provided for the reception of the four adjustable slides 8, t, which are
respectively the fence and feed-roller slides for each saw. These details are
the same on each side of the machine, that is, for each saw. The log u is
traversed along the table between the two sets of rollers v, u, of which there are
three on each side of the timber. The three rollers v are the "fence" rollers
or guides for the guage of the boards to be sawn. They are set to revolve ver-
tically in bearings in the slide s, so as to move with it, the bearings for the
upper ends of the roller spindles being, in the top plates x, carried on pillars y.
The set of rollers are geared together by spur wheels z overhead, so as to
work in concert, and the fence rollers are set up to the required distance from
the line of cut of the saw by the handle 1 on the projecting end of a screw 2,
which works through a nut attached to the under side of the slide. The set of
the fence is adjusted by a graduated scale on the edge of the framing, the edge
of the slide being made to act as the index. The opposite set of rollers w may
be similarly actuated to bear against the log by the handle and screw 3.
When once set up in this way to grasp the log on both sides, both the fence
and feed rollers are made to act in feeding forward the log to the cut. The
motion for this purpose is derived from the main shaft C, which has fast
upon it
a cone pulley 4, from which an endless band passes down to a similar but larger
pulley 5, fast on the feed shaft 6 beneath. This shaft works in bearings 7 in
the framing, and carries a worm or endless screw 8, gearing with a worm
wheel 9 on the horizontal shaft 10, working in end bearings 11, beneath the
slides. This shaft has a long sunk feather upon it, upon which are set the
four bevil pinions 12, so as to be capable of traversing with the roller slides
whilst they are carried round with the shaft. These bevil pinions gear with
similar pinions 13, fast on the ends of the centre roller spindle in each set.
By this means the timber is gradually traversed up against the cut of the saw,
the rate of feed being adjustable by shifting the band of the cone pulleyes 4
and 5, the proportions of the speeds of which are calculated to give all the
different feeds in exact unison with the overhang of the saw obtained by the
adjustable buckle. This is delineated in the two views, Figures 5 and 6.
The end of the flexible strap of the vibrating pulley has a metal plate 14

page_text: rivetted on each side of it, leaving a space between the prolonged portions of
these plates to embrace the stout piece of metal 15 fast on the upper end of
the saw to connect the plates 14 and 15. A bolt 16 is passed through the
three, a short horizontal slot being formed in the piece 15 to admit of adjust-
ment. This adjustment is effected by the thumb-nut 17 working on a small
screw 18, the opposite end of which has an eye 19, by which it is jointed to
the edge of the piece 15. The loose end of the screw is passed through an
eye 20 formed on the curved projecting end of the slide piece i, which is also
secured between the two plates 14. The centre of the side of one of the
plates 14, immediately beneath the connecting bolt, has a line cut upon it
to screw as an index for a graduated scale on the plate 15. Then when
the saw is ready for operation, the speeds 4 and 5, being adjusted to
the desired rate of feed, the upper end of the saw is adjusted to the proper
amount of rake for that rate of feed by slackening the bolt 16, when the
thumb-nut 17 may be turned back or forward to traverse the piece 15
between its holding plates until the index line on the latter stands at the point
on the scale coinciding with the rake required, when the bolt 16 is again
tightened up for use, as represented in my Drawings. This machine is
intended to be driven by any convenient power by means of the pulleys D;
but I may remark, that it may be actuated by direct steam power of its own,
a vertical steam cylinder being placed by the side of the main frame to work
a crank fast on the main shaft G, instead of the pulleys D; or the steam power
may be made to act not only as a moving power, but also for giving tension to
the saws, instead of the system of pulley adjustment herein-before described.
This may be effected, according to one modification, by placing two steam
cylinders in the foundation plate in place of the lower pulley, the centre of each
cylinder being in the same vertical line as the corresponding saw, and having
their piston rods connected to the lower buckles of the saws. The saws are
hung by a flexible band passed over an overhead pulley, just as delineated on
Sheet 1 of my Drawings. Both cylinders have their upper ports in free
communication with the steam boiler, and may have a steam pipe common to
both, so that a constant uniform pressure is kept up in the upper side of each
piston, the two being thus balanced and exerting their full power in giving
tension to the saws by pulling downwards. No valves are necessary for the
upper ports of the cylinders, but the lower ports require valves for the purpose
of admitting steam beneath the pistons at the proper intervals, to destroy the
balance of the two pressures and give motion to the saws. If, then, it is
supposed that one piston is at the top of its stroke, and the other at the
bottom, steam all the time pressing with equal force on each piston, then, to

page_text: bring the elevated saw and piston down for the cut, the valve of the opposite
one is opened to admit a portion of steam from the boiler beneath the piston,
to counteract, as far as may be necessary, the downward pressure of the steam
above it. The effect of this is, that the downward pressure on the piston is to
a certain extent negatived, or, in other words, the piston in that cylinder
becomes weaker, or exerts less downward tension upon the saw. This allows
the elevated piston to bring down its saw, elevating the other, when the same
movement is repeated for the cut of the other saw. In this way tension on the
saws is constantly kept up by the direct steam pressure on the top of the
pistons, whilst the periodical momentary arrangement of the balance affords the
necessary movement for the sawing action.
Figure 1, on Sheet 2 of my Drawings, is a front elevation of an arrangement
of sawing machinery, exhibiting another inode of applying direct steam power
both for the actuation of the saws and the tension thereof.
Figure 2 is a corresponding side view at right angles to Figure 1, one of the
standards being removed to shew the internal details. The main framing is
composed of two side standards A, A, which have each a plummer on their
upper end to carry the short horizontal engine crank shaft B. This shaft has
at one end a crank C, driven by the connecting rod D from the small direct
action steam cylinder E, whilst at the other end of the shaft a small fly wheel or
metal disc F is placed. So far as these details are concerned, the arrangement
is merely a small direct acting portable engine, which may be used either
simply as an engine for actuating any manufacturing or other machinery, by
taking off the power from the crank shaft B, or disc F; or it may be turned
to its more immediately legitimate use of sawing. To render it suitable for
this purpose, the disc F carries a crank pin G, from which a connecting rod
Hpasses downwards to a pin at I, in the small end of the long lever J, fast on
the end of the short horizontal shaft K, near the floor line of the lever, being
set to coincide with the vertical centre line of the saw guide L. This shaft
extends across the width of the frame, being carried in bearings in brackets M,
cast on the side standards, and it has fast upon it a second lever N, coinciding
in position with the centre line of the saw O, to the bottom end of which it is
attached. For this connection a short cross head O₁ is attached to the end of
the saw, and this cross head is attached by two short links P¹ to the end of
5 the lever N. This cross head is guided so as to work truly parallel in the
vertical guide L. The upper end of the saw is similarly connected by my
adjustable buckle, a cross head and links to the side rods P being guided
vertically by the guides Q, depending from the entablature or upper cross
piece R of the frame. The side rods P are attached at S to the cross head of

page_text: the piston rod of an overhead steam cylinder T, standing upon the entablature,
this cylinder being employed for the purpose of giving tension to the saw,
steam being constantly admitted beneath the piston. No valves are required
for this cylinder, the steam being kept constantly acting against the under side
of the piston tending to stretch or draw up the saw, and thus giving tension to
it to stiffen it during sawing. The lower steam cylinder E is of double the
area of the upper one, and when applied for sawing, the steam is only admitted
to the upper side of its piston, whilst the lower side of the cylinder is always
open to the exhaust pipe. By this arrangement it is to be understood that
both the upper and lower pistons come to the bottom and top of their respective
cylinders simultaneously. When both are at the bottom of their stroke, the
action will be that the upper side of the lower cylinder will be open to its
exhaust pipe, so as to free the lower end of the saw from downward pressure,
whilst at the same time the constant upward pressure of the steam in the upper
cylinder beneath the piston will still be acting, and will draw up the saw for
the upstroke. At the termination of this stroke, steam from the boiler is again
admitted to the top of the lower piston in the lower cylinder, the superior area
of which overcomes the upward pressure of the upper piston, carries the saw
down for the down or cutting stroke. In this way the two single-action
cylinders combined are equivalent to one double-action cylinder. It is obvious
that instead of this arrangement the tension cylinder might be beneath the
frame, the upper end of the saw being in such case connected with the shaft
above by a crank; or there might be a tension cylinder both at the top and
bottom of the frame, one piston rod being connected to each end of the
saw, either the top or bottom cylinder being made to act as the moving
power. A great advantage of this arrangement of saw frame is, that when
the saw is not required it may be disconnected from the moving powers,
and the engine may then be used simply as a prime mover for driving
circular saws, lathes, and other machinery. When necessary, the lower
steam cylinder E, or whatever other cylinder may be used for the purpose
which it fulfils, may be at once made double-acting, to work as a steam engine
by shifting a valve at the bottom, whilst the tension cylinder may be entirely
shut off in like manner. The saw may have the proper tension given to it in
another way, as shewn by the portions drawn in red, by placing a second
lever U on a shaft V, working in bearings near the upper end of the framing,
and connected to the upper end of the saw, this detail corresponding exactly
with the same parts in connection with the lower end of the saw.
The same
shaft V has also upon one end a lever W, exactly similar to the lever J;
beneath and from the pin of the lever W a connecting rod passes downwards

page_text: to the corresponding pin of the lever J, below. In this way, by lengthening
the rod X, by a screw or otherwise, or by shortening the saw itself, the latter
may have any required degree of tension given to it, and this arrangement may
be easily adopted without the use of the steam cylinder A, simply by putting a
fast and loose pulley on the crank shaft B instead of the crank, and connecting
this shaft with any suitable driving power. The log a, which is being sawn,
is traversed by the feed apparatus over the two bearing rollers b, b, working
in end bearings in the bottoms of the vertical slide openings of the feed
gearing, these rollers being drawn by my core pulleys, or other apparatus, to
give a regular adjustable feed. The log is kept down and steadied by the
upper pair of rollers c, c, carried in bearings adjustable in the slide openings,
in which are set the two vertical screws d, d, which may be actuated to move
the rollers up or down by the pair of bevil wheels e, e, and the horizontal
shaft and pair of end hand wheels f, f.
Figures 3 and 4, on Sheet 2 of my Drawings, exhibit a plan by which I
apply power to what are known as "belt" saws. A is the endless belt saw,
which is passed between two pairs of binding or nipping pulleys B, B, and
C, C, one pair being placed above and the other below the log to be sawn.
Each pair of these binding or friction pulleys is connected by gearing, so as to
have a simultaneous movement, an upper and a lower pulley on the same side
being carried in fixed bearings, whilst the corresponding opposite pulleys aro
hung on weighted levers to give the necessary frictional pressure. Both pairs
of pulleys may be actuated by straps from the same drum; but, in order to
give the necessary stiff tension to their saw, it is intended that the lower pair
shall be driven at a rate slightly higher than that of the other pair. By this
arrangement of endless belt saw, all awkward sudden bends over drums are
avoided, the loose portion a of the saw being left to follow its own natural
curvature, so that it may work at a high velocity without risk of accident.
The nipping pulleys may either be faced with leather or other frictional
material, or built up of rings of leather or other suitable substance.
Another branch of my improvements refers to the cutting of veneers by
means of my vertical sawing apparatus. A metal plate or sword is fixed
perpendicularly in the centre of the frame. This plate or sword is fixed
firmly into the frame close to the saw, so that the thin saw may bear on the
entire length of the plate, which is bevilled off on the edge next to the saw
teeth, just as in a common veneer wheel.
Figure 5, on Sheet 2 of my Drawings, exhibits a side elevation in detail of
a feeding motion, which is intended for feeding the timber up to the saw
instead of the ordinary ratchet movement, where teeth are actuated by

page_text: reciprocating catches and detents. In this arrangement, the wheel A supplies
the place of the ordinary toothed ratchet wheel, being plain on its periphery,
and truly turned like a pulley. A link B is set on each side of it, each having
an eye to work on the stud shaft of the wheel as a fixed centre, the opposite
ends of the links being inade to project slightly beyond the periphery of the
wheel, and having eyes C, to which the actuating rod D is jointed, and from
the pin of which joint is hung a short jointed link, carrying a saddle or friction
detent E. This saddle piece is curved to fit the curvature of the wheel's
periphery, and its connecting link is of such length as to bring it to a slight
angle with the centre line of the two links B. The rod actuates the apparatus
in the same way as with a common ratchet wheel, and when pushed in the
direction of the arrow, the links B, turning on their fixed centre, will draw the
saddle E freely and loosely over the wheel's periphery; but in the return
movement, when it is necessary that the feed action should be given,
the slight angle of the link of the saddle will cause the latter to bite or
squeeze firmly upon the wheel's periphery, and thus cause it to turn the
required distance upon its centre. To prevent the wheel from any back
action during the relaxation of the action of the rod D, a similar fixed friction
detent F is set on a fixed centre at G. This saddle, having its link set at a
slight angle with the radial line from the centre of the wheel A, it follows
that its action is similar to that of the saddle E, that is, when the latter is
slided over the wheel's periphery. In the back stroke the detent F holds the
wheel from a like retrogade action. On the other hand, when the detent E
draws forward the wheel, the second detent F slides to allow of the free
motion. This motion is perfectly noiseless, and the amount of feed given
through it may be adjusted to the greatest nicety without being dependant
upon tho pitch of the teeth of the common ratchet wheel. It is also obviously
applicable for several other purposes when power or motion is to be trans-
mitted, as for example, for purchases of various kinds, windlasses, the taking
up motions of looms, and other purposes.
Another modification of what I have termed my silent feed motion, for
feeding up the log to the cut, is represented in side elevation in Figure 6, on
Sheet 2 of my Drawings, and Figure 7 is a corresponding plan of the motion.
Here the log A is urged forward by the frictional contact of the two
pulleys B, on which it rests, these pulleys being arranged to revolve on fixed
centres C, whilst their shafts carry toothed wheels D in gear, with an inter-
mediate pinion E, fast on the shaft of the main driving pulley F. It is this
pulley F which takes the place of the usual ratchet wheel, being actuated by
a rod G, descending from an overhead eccentric, whence it derives its

page_text: reciprocating motion. The lower end of this connecting rod is jointed at H
to a segmental guide J, formed by two side plates of metal, connected
together transversely, and having their lower edges curved to the radius of the
pulley. The pulley has a plain cylindrical periphery, projecting laterally
on each side beyond the thickness of the rim, where the spokes join up
to the latter, forming the section indicated in Figure 7. Each side
plate of the guide J has two pairs of internal projections K at right
angles to the planes of the plates, and these projections are just far enough
asunder to embrace closely both the concave and convex surfaces of the
periphery of the pulley on each side, when bolted up. In this way the
end of the rod G is guided as it reciprocates, so as to move in the line of
curvature of the pulley's periphery. A stud bolt is passed at L through two
corresponding projections on the side plates of this guide, and this bolt has
fitted upon it a brass bearing, squared externally to fit to a short longitudinal
slot in the upper end of the curved link M, which is thus entered upon the
bearing. A small eccentrically ended lever N is also fitted to turn upon a
stud centre O, in the extreme end of the link, so that when turned down, in
the position shewn in the Drawings, the eccentric pressing down upon the
brass draws the link slightly upwards. The lower end of the link M has a
face piece P, bearing against the periphery of the pulley and two flat side
pieces Q, bolted transversely to embrace the projecting ring of the pulley.
The projecting ends of the frame pieces R, which carry the main pulley,
have a transverse stud fitted into them to carry a detent link S, formed
in the same manner as the catch link M. As represented in the Drawings,
the feed motion is adjusted for action. As the rod G reciprocates, the catches of
the link M slide loosely over the pulley's periphery during the rod's downward
stroke, the upper end of the link being pressed outwards, so as to release the
jam, whilst the pulley itself is prevented from moving in that direction by the
constant friction of the lower link or detent S; but as the rod G returns
upwards, the link M takes a firm hold of the pulley and turns it partially
round in the direction of the arrow, the detent S allowing it to slip through
its catches. Both the motion and detent links are secured in their hold upon
the pulley by the jamming arising from the counter pressures on the external
and internal surfaces of the pulley rim. When the lever N is turned over in
the reverse direction, the link is allowed to fall, and the change in the anglo
at which it stands, in relation to the rim of the pulley, releases the latter from
the jamming pressure; the same thing occurs with the detent S; the pulley
being thus simply released, when the log is to be quickly run back. But
when both links are brought into action, then the downward action of the rod
G always slackens the jam of the link M, whilst the upward motion again

page_text: engages it. The detent link being motionless, has a constant frictional hold.
I would here remark, that my improved vertical sawing apparatus may be
easily adapted to work in connection with a circular saw bench, so that the
compound machine may be used either as a vertical or circular sawing
machine. The feed apparatus for the circular saw may be used for the
vertical saw, so that with my pulley tension saw so adapted, nothing is
required to be fitted to the circular saw bench but the pillar, tension pulleys
and driving shaft. The vertical saw may be driven from the circular saw
spindle by means of a twisted or angular belt.
Although I have herein-before described my machinery as being actuated
either by direct or separately connected steam power, it will be obvious to the
practical man that the motive power is obtainable from the pressure of water, air,
or elastic gases; and although I have in one case mentioned that one of the
direct acting steam cylinders is to be double the area of the other, I would have
it understood that the proportions of the two cylinders may be varied to suit the
different modifications of the apparatus or the particular effect required, the
object in all cases of directly applied actuating cylinders being, the obtainment
of sufficient tensional strain upon the saw to enable it to cut accurately in
combination with the regular periodical arrangement of the equilibrium of
pressure on the opposed pistons, or the transfer of the balance of motive
power from one to the other. By giving the effective tension to the saws in
the modes which I have herein-before described, together with my system of
lateral guides or steadying apparatus near the cutting strain, I am enabled to
work with a much thinner saw than is usual at present, and thus considerable
economy results from there being less of the wood cut away. By the adoption
of my direct rotatory feed motion, that is by conveying the movement to the
feed rollers continuously, I present the timber to the saw with a constant
uniform pressure, which I consider to have a better effect as regards the
regularity and accuracy of cut than the ordinary broken or picking movement.
Having now described and particularly ascertained the nature of my
Invention, and the manner in which the same is or may be used or carried
into effect, I may observe, in conclusion, that I do not confine or restrict
myself to the precise details or arrangements which I have had occasion
to describe or refer to, as many variations may be made therefrom without
deviating from the principles or main features of my Invention. But 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 system or mode of constructing or arranging sawing machinery,
wherein the tension is given to the saw or saws, by means of adjustable
pulleys or levers, as herein-before described.

page_text: Second, the application and use, in sawing machinery, of one or more
saws formed into an endless belt for the purpose of giving tension thereto,
as herein-before described.
Third, the system or mode of constructing or arranging sawing machinery,
with a duplex alternate working action, as described in reference to Sheet 1 of
my Drawings.
Fourth, the system or mode of effecting the double purpose of actuating
and giving tension to the saws by means of variable pressure cylinders, as
described in reference to Sheet 1 of my Drawings.
Fifth, the system or mode, herein-before described, of actuating and
giving tension to the saws by means of two single-acting engines combined.
Sixth, the system or mode of constructing or arranging sawing machinery
so that the actuating power may be employed for other motive purposes, as
more particularly described in reference to Sheet 2 of my Drawings.
Seventh, the application and use of my continuous adjustable cone pulley
feed apparatus, as herein-before described.
Eighth, the application and use of my graduated adjustable saw-buckle,
as herein-before described.
Ninth, the system or mode of adjusting the overhang or rake of the saw,
in accordance with the rate of feed, as herein-before described.
Tenth, the system or mode of steadying the saws laterally by upper and
lower adjustable pins, capable of shifting to or from the point of cutting
resistance, as herein-before described.
Eleventh, the system or mode, herein-before described, of adapting my
vertical sawing machinery for cutting veneers.
Twelfth, the application and use of the noiseless feed motion, as described
in reference to Figures 5, 6, and 7, on Sheet 2 of my Drawings.
Thirteenth, the application and use of the jam counter-pressure catches,
as described in reference to Figures 6 and 7, on Sheet 2 of my Drawings.
Fourteenth, the system or mode of actuating endless belt saws by
differential speed-nipping pulleys, as herein-before described.
In witness whereof, I have hereunto set my hand and seal, the Seven-
teenth day of September, in the year of our Lord One thousand eight
hundred and fifty-two.
5
JOHN
(L.S.) MCDOWALL.
Signed, sealed, and delivered, in the

page_text: AND BE IT REMEMBERED, that on the Seventeenth day of September,
in the year of our Lord 1852, the aforesaid John McDowall, came before
our said Lady the Queen in Her Chancery, and acknowledged the Specifi-
in form above written.
cation aforesaid, and all and every thing therein contained and specified,
And also the
And also the Specification aforesaid was stamped
the Statute made for that purpose.
according to the tenor of