VARIOUS NEW AND IMPROVED METHODS AND MEANS OF WORKING WOOD, METAL, AND OTHER MATERIALS
Year: 1793

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I,
SAMUEL BENTHAM, of Queen Square Place, Westminster, in the County
of Middlesex, Esquire, send greeting.
WHEREAS His most Excellent Majesty King George the Third
did, by His Letters Patent under the Great Seal of Great Britain,
bearing date at Westminster, the Twenty-third day of April, in the
thirty-third year of His reign, give and grant unto me, the said Samuel
Bentham, His especial license, that I, the said Samuel Bentham, during
the term of years therein mentioned, should and lawfully might use,
exercise, and vend, within England, Wales, and the Town of Berwick
upon Tweed, my Invention of my "VARIOUS NEW AND IMPROVED
METHODS AND MEANS OF WORKING WOOD, METAL, AND OTHER MATERIALS ;"
in which said Letters Patent there is contained a proviso, obligeing
me, the said Samuel Bentham, by an instrument in writing under
my hand and seal, to cause a particular description of the nature of
my said Invention, and in what manner the same is to be performed,
to be inrolled in His Majesty's High Court of Chancery within four
calendar months after the date of the said recited Letters Patent.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the
said Samuel Bentham, do hereby declare that my said Invention is
described in manner following, that is to say:
1st. FORMATION of LEMINATED WORK FROM SHAVINGS.
:
Boards, when reduced to a certain thickness, which is different,
according to the nature of the wood, easily break in the direction of
the grain take two or more strata, cement them one on the other,
the grain of one crossing that of the other, or of the two others to
which it is contiguous, and the strength of the whole, as is well known
to workmen in wood; is very much increased. In this way, out of no
more than three, or even two shavings, I make a new kind of paste-
boards, which are applicable, with advantage, to a variety of purposes.
That the grain of the wood may receive as little injury in its texture as
possible in the operation of making the shaving, the plane I use for
the purpose is one in which the iron is much more inclined than ordi-
nary; in some instances, so much so as to be more like a spokeshave,
or a cucumber slicer, than what is commonly meant by a plane;
inasmuch as nothing but the cutting iron is made to pass between
the shaving and the wood from which the shaving is cut. Another
precaution, taken in the same view, is to wet the wood well just before
the shaving is taken off; this may be done with cold water, but with
still better advantage, hot water or steam. For the method of making
purpose to any breadth, see
a plane capable of taking shavings for this
the Specification belonging to the Patent lately granted to me for
my New Mode of Plaining. For strength in proportion to weight,
the great object to accomplish is, that a disconnecting force, in what-
ever direction applied, shall in that direction find the texture of the
substance, whether in respect of natural grain or artificial configuration,
such as shall enable it to oppose the greatest degree of resistance. On
these principles not only boards, but tubes of wood and other materials,
may be composed of a hitherto unprecedented degree of lightness in
proportion to strength, or strength in proportion to lightness, according
as the one or the other quality is principally in view. This may be
done by the winding a single veneer or shaving spiral-wise tight round a

page_text: mandril, the edge of each succeeding coil fitting exactly close to that
of the preceding one, and being made to stick to it by means of a
glue or any proper cement. A tube composed in this manner of a
single stratum may serve for some purposes, for other purposes, the
stratum, thus formed, may be strengthened by a stratum of paper or
linen, or other cloth, either within side or without. For others, again,
the strengthening may be given by a second stratum of thin wood com-
posed of ribands, of which the grain runs in a direction parallel to that
of the axis of the spiral. For others, again, on the first spiral wind
another, turning in the opposite direction. Two strata thus applied
to each other may be cemented together not only at their edges but
throughout the whole extent of their contiguous surfaces. In this
way tubes may be made either round or oval, or even angular, so
long as the angles are not sharp enough to break the texture of
the wood or other substance. A tube thus formed will be the more
perfect if while it is on the mandril, but before the cement is set,
it has been made to undergo an uniform pressure on the outside,
in the manner, for instance, in which metal is pressed into shape
by swedges. To make in lengths a tube for pipes of any length
required, make the component lengths taper in such manner that
the smaller end of one shall fit into the larger end of another. To
make a bent tube, the ribon, if applied with the same regularity
as above supposed, must, it is plain, have their edges not parallel
to each other, but sometimes converging, sometimes diverging, in
such manner as that the ribon shall be broader when it comes to
the outer part of the bend and narrower when it comes to the
inner. In this manner tubes, though bent, may be made without
any difficulty so long as the diameter of the tube is either all
along the same, or tapering, and the bend such as will admit of
the mandrils being drawn out of the tube; where no such degree
of regularity takes place, different contrivances may require to be
employed. 1. In some cases, where the value of the mandril is not
regarded, for instance, if it be of clay it may be got out piece-meal.
2. Where the mandril is to be preserved one method is to use a
hollow mandril, and in the part where a swell, for example, is to be,

page_text: let it be pieced or laid open, leaving only so much substance as is
necessary for strength. Over the part thus laid open tie at each
end a bag, composed of some flexible substance, leather, for example;
have ready a mould opening in two cheeks, like swedges, to the
size and shape of the swell; at one end of the mandril introduce
any kind of powder, such as sand, sawdust, &c., which, when rammed,
shall fill up the bag to the swell required, the bag being supported
externally and kept to its shape by the mould which is then to
be taken off. Having now formed the tube upon the mandril, bore or
pick out a core from the sand or sawdust; the bag may thus be
emptied and the mandril may be drawn out. But to enable it to be
drawn out, it is evident that at the open or perforated part of it, where
it is enveloped by the bag, its diameter must have been reduced to the
amount of the thickness of the bag. 3. But instead of powder a fluid
may, in most instances, be employed to more advantage. This fluid must,
of course, be of such a sort as, when introduced into the bag, may be set
by cooling, or any other means by which it may alternately be made to
assume the fluid or the solid form. The means employed to produce
this alteration must, it is plain, be in every instance such as shall do no
injury to the materials of either the tube, the cement, or the mandril
(where that is intended to be preserved), and, at the same time, such
as admit of the fillings being easily got out, without the expence and
inconvenience of leaving any considerable residuum in the tube. In
all these points of view, the fusible metallic compounds which liquify
in a degree of heat not greater than that of boiling water may be
employed in many instances with evident advantage, especially as in
this way you may omit altogether the bag, the formation of which will,
on account of the puckers in it, be but a troublesome operation. In the
instance of a metal, such as iron, where, for want of a perfect fusion or
welding, or for any other cause, the same mass is in different parts of
it liable to possess different degrees of strength, the compounding it of
thin lamina may be productive of an advantage analogous to what is
obtained by decassating or twisting, in the case of wood, since, the
thinner the laminæ the more accurately their texture may be scruti-
nized into and tried, and the more numerous they are, the greater

page_text: the probability that, in a tube thus formed, the weakness will not in
any part of its length be found to pervade the whole thickness. The
component tubes may be twisted either in the same direction, or in
contrary directions. If in the same direction, care should be taken
that, in the second, or outward spiral, the joinings should be brought
not to the line where those of the first or inner spiral are, but rather
at the greatest distance from that line; by this means, whatever
imperfection results from the line of junction in one thickness will be
covered by an intire coating in the other. If the ribons are twisted
in opposite directions a similar advantage will be obtained, except that
at every point of intersection there will be a lozenge-shaped speck, of
which the comparative unsoundness or weakness will pervade both the
strata, which speck will of course be greater or less, according to the
accuracy of the work. To remedy this imperfection, if in any instance
it were thought worth while, the specks may be bored out, and the
hole closed again, with a screw of the same material with the main
substance of the tube. Several strata thus twisted together preserve
their form inuch better than a single one of the same thickness would
do during the operations of soldering, brazing, or welding. For these
purposes they may be heated in a reverberatory or other furnace, without
being in contact with the fuel, and, if requisite, they may be inclosed
in a case, to defend them from the blast of air: Where welding is
employed, it may be performed either by percussion applied to the end
or aperture of the tube, so as by shortening it by successive strokes to
close the clinks left between the threads (as in the mode called jumping,
at present used for gun barrels twisted in a single spiral), or by swedges,
pressing on the outside, while a mandril, forced in, either at the same
It is obvious
time or immediately after, serves to finish the inside.
that in this way may be made pistol and gun barrels. Cannon of any
size may also be formed in this manner, instead of by casting; and an
infinite variety of articles that at present are made solid, may thus, for
lightness sake, be made hollow, without prejudice to the requisite de-
gree of strength, and the different strata may be of different materials
as beauty, strength, inflexibility, durability, or other considerations may
require.

page_text: II. SAWING BY A RECIPROCATE MOTION, USUALLY AN
UP-AND-DOWN ONE.
The saw mills hitherto used have scarsely been employed to any
other purpose than that of sawing timber longitudinally into boards and
scantlings. A saw mill of this sort consists of a saw frame, moving
up and down, in which one or more saws are fixed, and a horizontal
bed, on which a piece of timber is held, while the bed is moved on
towards the saw; the saw frame is confined to its course by fixed
channels. By the up-and-down motion of the saw frame a progressive
motion is given to the bed on which the piece lies, whereby, at every
descent of the saw, the piece is cut to a certain depth, and at every
ascent the piece is advanced; this advancement is made by a rack and
pinion, set in motion by a ratchet wheel, of which a tooth is laid hold
of by a claw every time the saw goes up. Thus far, generally speaking,
I adapt the same-contrivance in my sawing machines. 1st, for dimi-
nishing the friction between the saw frame and the channels it moves
in, I employ friction wheels or rollers, so placed that the saw frame is
compleately guided by them without rubbing against any thing else;
or an apparatus may be employed, consisting of a combination of levers,
an example of which may be seen in a what is called the parallel
motion apparatus for the piston rods in Messrs. Boulton and Watts
steam engines. With respect to friction wheels, if the saw frame is
to move in a direction perpendicular, or nearly so, I make use of four
pairs of wheels, all of equal diameter, each pair connected with each
other by a common spindle, the length of the spindle being deter-
mined by the extent of the saw frame breadthways so that when
the spindles are placed in the fixed part of the machinery, the
wheels shall apply themselves to the perpendicular bars of the saw
frame;
the position of all the four spindles should be horizontal
and parallel to each other; at any rate, at right angles to the direction
of the saw frames. Two of these spindles should be placed on the
same level with each other, and a little below the bench or floor on
which the peice is to be cut is advanced; the other two spindles should
be placed over these, at a sufficient height, according to the length of

page_text: the saw frame. The centers or bearings in which these spindles turn
should be fixed in the framework of the machine, in such manner as to
be adjusted to their perfect position by wedges or otherwise, in any of
the ways in use among millwrights. These friction wheels, embracing
thus the saw frame on the front and back part of it, above and below,
will insure the straitness of its motion in one direction. To confine
it in the other direction you may fix perpendicular slips to the saw
frame, so as to act against the sides of the wheels, or you may apply
additional wheels to the side of the saw frame, in the manner those
above mentioned were applied to the front and back of it. If the
motion of the saw frame is to be horizontal, or very much inclined, the
rollers on the upper side may be omitted. In cases where, besides the
reciprocate motion, a progressive motion is given to the saw as it acts,
its frame may move between two pair of cylindrical rollers, the axes of
which are placed in the direction of the progressive motion of the saw ;
for example, in the cutting of stone by a horizontal motion, where the
saw is to sink perpendicularly as it enters the piece, for a simple
machine for cutting one cut at a time, the saw frame may, in its general
form, agree with those in use at present among stone cutters, but
instead of the twisted rope joining the upright bars of the saw. frame at
their upper ends, the contraction of which rope is to stretch the saw
fastened at the lower ends, let the upper ends be joined together firmly
by an additional horizontal fixed bar; or the horizontal bar, used at
present for no other purpose than that of resisting the action of the
rope, may be made of sufficient breadth and strength to resist the forse
with which the saw is to be stretched. The stretching may on this
plan be performed by screws, or otherwise, as in the saws for cutting
wood. For guiding a saw frame of this sort in its course, these up-
rights may be broad enough to slide to and fro the whole length of the
stroke between cylindrical rollers, which, in this position of the saw,
must be perpendicular, turning upon perpendicular axises, supported by
fixed frame work. These rollers must be of sufficient length, that is,
of sufficient height to guide the saw frame from the elevated situation
which it occupies at the entrance of the saw into the stone, to the
inferior situation which it occupies when the stone has been cut through.

page_text: It is evident that, in this case, the uprights must be perfectly straight
and out of winding, as well with respect to each other as with respect to
the saw.
Where several cuts are to be made in stone at once the
apparatus will require some such variations as the following: conceive
an oblong frame composed of two parallel longitudinal bars, joined
towards each end by two parallel transverse bars; between these trans-
verse bars are fix'd the requisite number of saws, so as to be stretched
by screws or otherwise, in the same manner as the saws for cutting
wood. This frame is of such dimentions as to receive within it the
largest block which the apparatus is intended to saw, in such manner
that as the saws in cutting sink into the block the block may thus rise up
as it were within the frame; moreover, in point of length, to the longest
block which the machine is intended to cut, must be added a further
length, equal to that of the stroke. This horizontal saw frame, in
which the saws are stretched, may be guided and confined to its course
by a vetical frame set down upon the middle line of it and firmly con-
nected with it by braces. This vertical guide may be of the same
figure as the vertical saw frame above described, for cutting with a
single saw, and confined in the same way to its course by perpendicular
rollers.
To return to wood. In the present saw mills it is in the descent of
the saw that the saw cuts, and in its ascent that the piece moves on
to it; on this account, though the motion of the saw is perpendicular,
the position of the front, or cutting part, of it is inclined, the upper end
overhanging the piece as much as the saw is intended to cut. In this
case, to vary the length cut at a stroke, the angle of inclination must
be varied. I find a convenience in giving such a position to the saw
as that the points of the teeth shall be in a line nearly parallel to its
motion, in which case I make the piece advance while the saw is
cutting in its descent; thus, by regulating the advancement of the peice
alone, I can regulate the length of the cut, the saw remaining always in
the same position. I have sometimes advanced the peice by a weight,
but then the weight should be prevented from acting while the saw is
ascending. For sawing a veneer, that the saw may work the easier
and the saw dust have the more room to escape, I fix to the bench or

page_text: floor a wedge, the edge of which applies itself as near as possible to the
back of the saw, so as to enter into the saw kerf as the peice is advanced,
and open it more or less, according to the sharpness of the wedge. If
a thin peice is to be cut from a thick one, a veneer for example, from
a thick block or log, then one side of this wedge should stand in a line
with that side of the saw which is towards the thick part of the peice,
so that the inclination of the wedge shall bear off the thin part only.
If the peice is to be cut in the middle, or nearly so, then the wedge
may stand so as for the middle line of its thickness to be straight with
the middle of the thickness of the saw; thus, by varying the position of
this wedge, the two parts into which a peice is cut may be borne off
from the saw, each more or less with respect to the other, according
to their relative degrees of flexibility. If two cuts are to be made
in a peice, so as to divide it into three parts, each of the two side
parts may thus be borne off from the middle part. If the friction of
the peice against this wedge be considerable, you may place a cylin-
drical roller close behind the wedge, or you may put friction rollers in
these wedges, so that when the peice is advanced so far as to bear upon
these rollers the sides of the wedge will be no longer rubbed against. If
the action of the wedge by thus bearing of one of the parts is so strong
as to bend the whole of the peice out of its direction, this effect may be
counteracted by a roller, stationed just before the teeth of the saw, so
as, by a spring or weight, to press against the side of the peice and
keep it to its direction. If, to make a saw stiffer or stronger, it be
made thicker at the back, like a knife or razor, although it would work
very hard till the whole of the saw had entered the peice, yet, by placing
a wedge or cylindrical roller close behind the back of the saw, the thin
peice or veneer would, as soon as it reached the roller, be borne off, so
as no longer to be touched by the thick back of the saw; this back
may be either of the same substance with the saw or may be fastened
to the side of it. A case in which a saw thus strengthened is par-
ticularly requisite, is where, for cutting as little as possible from the
rough side of a peice for the purpose of making it even, the saw will,
by reason of the inequality of resistance, be apt to be thrown off to the
outside, instead of penetrating the substance without deviation from the
B

page_text: straight line. To confine the saw the better to its direction, and prevent
its being twisted by the above or any other cause, I sometimes employ
a pair of guides, consisting of peices of hard wood or metal, having
each of them a slit, in which the saw itself moves, and by the sides of
which the whole breadth of the saw, the teeth only excepted, is embraced:
one of these guides is fixed as near as possible above the upper surface
of the peice, the other, as near as possible, below the under surface.
It is plain that, to move easily in these guides, the thickness of the saw
must be very regular.
For cross cutting, I give the saw a sort of frame, in which, instead
of the saws being stretched between the two uprights, the horizontal
bars are made to extend beyond the upright ones, and the saw is
stretched at the extremities of the horizontal bars, the saw being fixed
in a direction which, with respect to its frame, is at right angles to that
which it assumes when fixed for longitudinal cutting, that is to say, in
a direction crossing the sliding bed, instead of parallel to it. Of these
horizontal bars the projecting part must be of such a length as to admit
of the thickest peices being cut through before it is stoped by the
perpendicular bars. Provide the sliding beds now with stops and
supports, proper for confining the peice to the position required, and
by preserving the same stops and supports, any number of peices,
whether straight or curved, may be cut to the same length and angle
thus much where the cut is to go through. Now suppose it is to stop
short at a certain depth; if this partial cutting is to be performed on a
single peice only, or a small number of peices, it may be done by
stopping the action of the machine as soon as the cut is observed to
have attained the depth required. When a certain number of peices
are to be cut to the same depth, it will be proper to adjust the
machinery in such a manner that each peice shall be cut, one after
the other, invariably to the same depth. To produce this effect, it
might be sufficient to adjust matters as that the action of the machine
shall be stoped by an obstacle opposed to the bed, or to the peices, as
they are drawn on against the saw, but if the mode of advancement
above spoken of be used, such stoppage would damage the machine.
To avoid this inconvenience, effect the stoppage rather by disconnecting

page_text: the motion of its sliding bed from that of the saw, which will thus play
up and down without acting any more upon the peice. This effect
may be produced in a variety of ways; where, for example, the depth
of the cut does not exceed the quantity that corresponds to a revolution
of the ratchet wheel, fill up one of the notches into which the claw must
fall to pull on the wheel, so that when that part of the ratchet wheel
comes to the claw it shall no more be laid hold of. When the depth
is greater than as above, adjust to the bed something that, when the
bed has advanced to the required distance, shall apply itself to the claw,
and prevent its laying hold of the ratchet wheel. In this way tenons,
for example, may be shouldered by the apparatus for cross cutting, and
cut lengthwise by the apparatus for longitudinal cutting. For the
latter purpose, if many similar tenons are to be cut, it will be more
expeditious to use two saws in the frame, the distance between them
being adjusted to the thickness of the tenon.
in
For cutting curve fashion the saw may be fixed in its frame, either
in the manner just described, or, according to the nature of the work,
any other manner that admits of the supports being situated out of
the way. By a saw thus playing up and down to cut a curve, you need
only make the piece to advance in a direction adapted to such move.
In cutting circularwise (in cutting fillies of wheels for example) the
business of directing the course of the peice may be performed by a
pair of calipers, lying flat on the bench or floor and moving about a
center, which calipers are, at their extremities, furnished with teeth
proper for laying hold of the ends of the peice; the arms of these
calipers must be of a length equal at least to the radius of the circle
to be cut. To prevent their separating when the peice introduced
between them is to be laid fast hold of, employ a cross bar from one
arm to the other with pin holes adapted to the different angles to which
there may be occasion to open the calipers for receiving peices of
different lengths. The operation of advancing may in this case be
performed in the same manner as in that of rectilineal sawing, except
that the rack, instead of being straight, must be bent to the segment of
a circle and fixed concentrically to the calipers.
Pieces may be cut to an elliptical form by the apparatus described

page_text: above for cutting circular peices, only for holding the peice substitute
an oval trammel instead of the calipers. But in the following manner
a peice may be cut to any irregular curve: cut first a thin peice of wood
to the curve required, and near each end bore a hole to receive a sharp
point to serve as a tracer; lay this mould on the saw bench, in such
manner as that one end of the curve shall touch the teeth of the saw,
and point in a direction along the side of it; advance now the mould in
the direction it assumes in consequence of its being kept throughout its
progress as near as possible flat against the whole breadth of the saw,
and the points fixed near each end will have traced on the bench the
line they respectively disribed during the moving on of the mould;
then, according to each of these lines, cut in the bench a channel of
sufficient breadth to receive a stout pin; now lay the mould on the
peice to be cut, and mark on the peice the spots where the points or
traces were placed in the mould; at these two spots bore holes to
receive a stout pin in each, corresponding to the tracers in the mould;
lay the peice on the bench with the pin at each end inserted into the
corresponding channel, then will the end of the peice be applied as the
mould was before to the teeth of the saw, and when the saw is set in
motion, if the peice be advanced, the pins sliding along in the channels,
the peice will thereby be guided so as to be cut to the curvature of the
mould. In this way curved peices, the ribs, for instance, of a ship or
boat may be cut out.
How to cut to bevellings and to windings.-The angles which two
contiguous surfaces of a peice form together at their meeting, and
which is not a right angle, is called by some workmen the bevelling.
The cutting a peice then to any bevelling, the bevelling remaining
the same, may be easily effected by the position in which the peice is
confined on the sliding bed, and that in longitudinal sawing as well
as cross cutting; but if the bevelling is required to vary in the course
of the cut so as to produce a winding surface, forming certain given
bevellings, and those different ones at different positions of its length,
for this purpose the following apparatus may be employed:-Let
the frame or bench on which the sliding bed moves, when there is a
sliding bed, and on which the peice itself moves when there is no

page_text: sliding bed, be made to tilt or turn on a pin or gudgeon at each end,
so placed as that, if joined, they would form an axis, passing lengthways
through the middle of the bench at the height of the upper surface of
whatever is used to support the peice, and through the saw. On one
side of this axis let the bench be loaded in such a manner that if it had
no support it would drop on that side till it assumed nearly a vertical
instead of horizontal position. From the under part of this side project
a leg or support downwards towards the floor, then let a wedge or
waved mould, which may be called a director, the motion of which is
connected with that of the peice to be sawn, be made to slide on the
floor under this leg, and let the thickness or height of this director at
different parts of its length be adapted to raise the leg of the bench
more or less, according to the angle the bench should make with the
saw, in order to give the required bevelling to the peice at different
portions of its length, the saw itself moving all the while invariably up
and down in its perpendicular direction.
Reciprocate sawing machines have never, I believe, been applied to
the cutting any other substances than wood or stone; besides these I
apply them not only to ivory, bone, and such substances as are usually
cut with edged tools, but to metals and other substances, so as to perform
with machinery all sorts of sawing that is now performed by hand.
These machines may not only be worked by any of the greater forces
applicable to mill work, but also by manual labour, and that to great
advantage where a number of peices are to be cut alike. The size
and strength of the machine must of course be adapted to the work it
is to do; and when human labour is to produce the motion it may be
communicated not only by a crank and fly wheel, worked by a winch or
treadle, but by a lever, like a pump handle, or in any other of the modes
used for turning lathes or other machines. The saw is not the only
tool to which a reciprocate motion may thus be given with advantage.
By a similar apparatus it may equally be given to an edge tool without
teeth, to a kind of chisel or goudge or knife, as also to a file, rasp, or
any other grinding or polishing instrument, while the peice is presented
to the action of the tool in the direction required, and in a
suited in each case to the nature of the work.
manner

page_text: III. WORKING BY A RECIPROCATE LATHE.
From the reciprocate motion, as applied to sawing, it will be easy to
conceive a new mode of working by means of an engine, which I call
a reciprocating lathe. I call it a lathe, because it is by the motion of the
peice that the tool is made to act, the tool itself being supported on a
rest. In a turning lathe the motion of the peice is circular or oval, or
at any rate in a recurrent curve, whereas in the reciprocate lath the
motion of the peice is straight, or, if curved, not rotatory, but backward
and forwards, or in one word, reciprocate. Suppose that to either of the
reciprocate saw frames a peice of wood, for example, be fixed, instead of
a saw, so as to play up and down as the saw did. Now it is plain that
if a tool of any kind like a turning tool be held against the peice of
wood it may be made to receive a cut, which shall in the longitudinal
direction be strait, and in the transverse direction of any given figure,
depending on the shape or manner of application of the tool. A man
used to turning will thus make any straight moulding as easy as he
does a circular one in a turning lath. So most of the contrivances used
in engine lathes, to vary the figure of the peice, may, wherever it may
be thought worth while, be applied to this reciprocating lathe. In this
manner a peice of any sort of material, such as wood, ivory, metal, stone,
&c. may be held, not only for the purpose of receiving its form, but for
the purpose of being polished, the instrument, whatever it be, that is
made to act on the peice being presented either by hand or in any
other more advantageous manner, according to the nature of the work.
Under the head of Sawing there was occasion to mention the
necessity, in some cases at least, of the saws being of an exact and
regular thickness. Sometimes, to do without being set, it should be
thicker at the teeth than at the back, yet however tapering in the
direction of its breadth, in that of its length it should be all along of a
thickness exactly parallel. In the methods hitherto used for grinding
saws, neither this shape nor any other can be given with any degree
of accuracy. A reciprocate lathe is particularly suited to this purpose;
the saw may be stretched as if it were for cutting, then by holding an
edge tool or grinding instrument to one side, a support being provided

page_text: at once.
on the other, the two sides may be wrought successively, or by placing
two tools, one on. each side, acting one against both sides, may be done
These opposite tools may be made to close in upon the saw, by
screws or otherwise, till it is reduced to the form required. Instead of
this particular construction of the frame used for holding the saw, may
be substituted one more suitable to the task of supporting the peice
against the action of the tool, and this frame, which now be called
the reciprocating lathe bed, may be furnished with stops and con
trivances for the more ready laying fast hold of the peices to be
worked. The motion given to a reciprocate lathe need not be confined
to the perpendicular one usually given to the saw in the sawing
machine. No experienced engineer will be at a loss to produce a
reciprocate motion to any extent and in any direction required, per-
pendicular, horizontal, or inclined: The motion of a crank seems
particularly applicable to produce this reciprocate motion where the
extent of it is not too great, and the sort of crank for this purpose
should be such in which the crank pin being provided with different
holes in a flaunch, at different distances from the center (in any one of
which holes it may be inserted), or being made moveable in a slit, the
extent of the reciprocate motion may thus be varied at pleasure. By
varying the extent of the motion the lathe may easily be adjusted to
working any such peice as, though strait to a certain extent, has at
the extremities of the strait part projections, such as would prevent the
application of a plane. A mode in which the action of this reciprocate
lathe may be varied, is by making the bed move or vibrate in the
direction of the segment of a circle, an ellipsis, or any other curve, or,
in short, in any other direction, by means of guides. See the article
of Sawing, as applied to irregular curves.
IV. GIVING CURVATURE BY BENDING.
Bending is another, and in many instances more advantageous mode
of giving curvature to wood, and may be performed with or without
steaming, according as the case requires. Where the thickness required,
compared with the sharpness of the curvature, is such as renders it
impracticable to bend the peice entire, it may be divided for this
Bending is another, and in many instances more advantageous mode
of giving curvature to wood, and may be performed with or without
steaming, according as the case requires. Where the thickness required,
compared with the sharpness of the curvature, is such as renders it
impracticable to bend the peice entire, it may be divided for this

page_text: purpose into different thicknesses, with very little, if any, loss of strength,
and, if the strata are connected by proper fastenings, with a degree of
strength far superior to what a peice of the same dimensions would
possess if grain cut. The use of steaming wood for the purpose of
bending it is to supple it, so as to enable it the more easily to be
brought to the form required, as well as render it more apt to stay in
that form after the pressure by which it was originally brought to that
form has been removed. The effect of steaming the wood is the applying
heat and moisture to it. If it has already moisture sufficient as in the
case of green wood, heating in any other way, without the application
of steam, may suffice, or the effect may be produced by heating and
wetting at the same time. The above three modes of suppling by heat
and moisture have been practised from time immemorial in Russia,
and applied to wheels and some other sort of woodwork. In England
they, or some of them, have been long applied to the bending of planks
for ships in the King's and other dockyards, by Messrs. Jacob and
Viney, under a Patent now expired, to wheels; and by Mr. Bevan,
under a Patent still in force, to "circular wooden sashes, soffits, fan
lights, door mouldings, and hand rails for stairs," and prehaps, in some
few instances, by cabinet and chair makers in general, without Patent,
though in no instance that I have ever heard of, here or elsewhere,
has the expedient been recurred to of dividing a peice for this purpose
into thicknesses. But where curvature is required there is no branch
of woodwork to which, by help of the expedient of division into thick-
nesses, this mode of curvature may not be applied, and that even in
the cases where the peices at present employed are of the greatest thick-
ness. In this manner curvature may be given, where required, to the
woodwork of all sorts of engines, and of carriages of all sorts; also to
the timbers of all sorts that are or may be designed to receive a
curved shape, for the purpose of being employed in buildings; and to
any of the timbers, without exception, that are or may be employed in
the construction of boats or vessels, ships of the largest class not
excepted, in which latter instance a vast saving in point of quantity
and value, as well as a considerable increase in point of strength, might
be effected.

page_text: Screws may also thus be formed of wood; the male screw by
bending the thread about its stem, the female by twisting a slip
round a false step or mandril, on which it is confined by a shallow
channel, or otherwise, to the proper angle, while it is forced into a hole
prepared to receive it; a little glue on the outside of the spiral slip
would be sufficient to hold it in its place while the false stem is drawn
out, afterwards, the male thread and the spiral slip, the interstices of
which constitute the female skrew, may be secured in their respective
positions by pins or other meane.
-
In the operation of bending a very material caution is, that as fast
as you forse any peice to adapt itself to the curvature of the mould to
which you are bending it, you apply a pressure, by means of wedges or
skrews, &c. to that very part, and so all along the peice, particularly
at the sharpest convexities, not trusting to the force applied to any
other part of the peice, lest such force, though sufficient to keep the
peice to its curvature, should not prevent the exterior fibres from
starting out. In the forming, for example, ship ribs of all shapes and
sizes, in order to supersede altogether the use of crooked grown timber
in every instance where strait would be cheaper, there need no more
than the making use of one or other of the two methods following:-
First, having formed a mould or block to the shape of the rib in
question, comprehending the whole of its extent from top side to top
side, (that is on both sides the keel,) bend the component parts of the
rib according to the shape of the block, and fasten them together;
then, to confine the whole rib in its curvature, apply stays or cross bars,
according to the places where the form would be most apt to change,
and so convey the rib, stays, and all to its place, not taking the stays
off till the rib has been sufficiently confined to its curvature by the
connexion given to it with the planks, beams, and other parts of the
ship. Or, secondly, you may form the shell of the ship first without
timbers, beginning to build it, as it were, by the planks, using only a
set of temporary moulds or false ribs to determine the position of and
give a temporary support to the planks; this done, insert the timbers
afterwards, pressing and binding the component parts successively into
their places, and removing the false ribs in proportion as the real ones
a

page_text: are put together and secured. Or, thirdly, instead of these false ribs,
you may insert a sufficient number of real ribs, put together, as in the
first method, and then proced with the plank and the rest of the ribs, as
in the second method. As to bending, it may in this case be performed
with or without the assistance of steaming and with or without the use
of the expedient of dividing into thicknesses, according as the degree
of curvature may require. In clinker-work built boats, the ribs have
sometimes been inserted by bending them to the planks, but this only
in boats of the slightest class, and, I believe, in no instance in which
the peices of wood employed for the ribs have exceeded an inch in
thickness. In this kind of work, to make the junction between rib
and plank close and firm, the notches or recesses left by the lapping
over the planks ought first to be filled up at the place of insertion of
each rib and the surface thus made flush before the rib is inserted.
V. WORKING BY A ROTATIVE MOTION OF THE TOOL.
In the instance of circular saws, not to mention boring and grinding
tools, working by a rotative motion has already been used, as I under-
stand, in a few instances, such as cutting timber into boards, cross
cutting logs for fire wood, cutting mortises for ships blocks, cutting
the teeth of cog wheels, and other slight indentures in metal. But the
idea of adapting the rotative motion of a tool, with more or less ad-
vantage, to the given to all sorts of substances any shape that can be
required, is my own, and, as I believe, intirely new; I place it accord-
ingly amongst the inventions of which I claim the exclusive property,
in as far as it has not yet been reduced to practice by others, and in as
far as the contrivances here described afford sufficient instruction for
producing the effect. To take the simplest mode of fitting up a circular
saw for cutting in this way, conceive a spindle, furnished with a circular
saw, turning between two centers, as if in an ordinary turning lathe,
with a rigger or pulley to receive a band. Let the saw be strengthen'd
and confined to its position by two flaunches, one on each side of it, of
equal diameter one to the other; as this diameter limits the depth of
the cut which can be given by the saw, it should therefore be no
greater than what is necessary to give the saw the requisite degree of

page_text: stiffness. Immediately over the spindle fix a bench of a size adapted
to the support of the work you have to perform and crossing the
spindle at right angles. In this bench make a slit for the saw to play
in, projecting above it, more or less, according to the depth of the peice
which it has to cut. Standing now in the direction of the saw, put it
in motion in such a manner as to make the upper part move towards
you as it turns; shoving the peice on against the saw it will be cut
through. Where a rigger, if small enough not to come in the way of
the peice, would be too small to give motion to the saw, its office may
be performed by a cog wheel of somewhat less diameter than the
flaunches, to which cog wheel you may give motion by another cog
wheel fixed to a rigger of a larger size, turning on a seperate
spindle.
1. How, by means of a rotative saw, to shape a peice from the rough;
a peice of wood, for example, in the state of a trunk or log, or a small
branch of a tree, or a peice of metal as it comes from the crucible or
the forge. The first thing to be done is to give it a strait side;
for this purpose the business is to advance the piece in a direction
exactly strait against the saw. For securing this straitness more
methods may be employed than one; the following I have found as
commodious as any :-Cut in the bench a longitudinal channel, in a
direction parallel to the saw, and the nearer to it the better. Into
this channel or groove insert a bar or tongue so as to fit exactly, and
yet slide with ease, but without projecting above the bench. On this
longitudinal bar fix two transverse bars, projecting their whole thickness
above the bench; one of them fixt and the other moveable, so as to
be fixed at different distances from the former, the distance being
Of
adjustable to the length of the peice which is held between them.
these transverse bars the foremost, it is evident, cannot, at that end of
it which points to the saw, extend beyond the saw, since if it did it
would be cut off by it; the hinder may or may not, according as the
purpose requires or not that it should, pass the saw. The longitudinal
bar thus furnished with the two transverse ones forms what I term the
slider. To diminish the friction, between this bed and the bench or
floor on which it slides friction rollers may of course be applied, and

page_text: that either to the bench or to the bed. To this slider make, fast the
rough peice by any means, and so shove it along from end to end
against the saw; the consequence is, that if the saw be deep enough
either the peice will be simply cut to an even surface on one side or
it will be cut into two distinct peices, each having one such even or flat
side. Fix now one of these peices on the slider with the flat side
downwards, shove it against the saw as before, and in this manner this
peice will acquire a second smooth side contiguous to the former, or
be cut into two other peices, each having two such contiguous smooth
sides. The angle formed by these two contiguous sides will be a right
angle while the upper surface of the bench is parallel with the saw
spindle, but if it be required to give the piece any bevelling this may
be done by making the bench to turn or tilt on pins or gudgeons, like
that above described for cutting to any bevelling, by up and down saws;
or the saw spindle may be made to tilt, the bench remaining fixed; or,
the bench and spindle remaining as before, the peice itself may be tilted
and confined to the slider, so as to meet the saw at the angle required.
Peices of any figure, by being confined to this slider by stops and sup-
ports, may be cut lengthwise or traversely to any angle or length.
In speaking of cutting from the rough, we showed how to give a peice
two strait sides; as to the remaining sides, though the peice might
be fixed to the slider again, yet to save the time that might be con-
sumed in adjusting and confining the peice according to the dimensions
required, the following method may be employed: let a bar of wood or
metal, which we will call a guide, be applied to the bench longitudi-
nally, in a direction exactly parallel to the saw, and (as in general it
will be more convenient) not on the same side as the slider is. This
guide should move so as to be set at different distances from the saw,
preserving always its parallelism with respect to the saw.
If the peice
to be cut be applied with one of its flat sides lying on the bench, and
another pressed flat against this guide, advance it now against the saw,
and so much as extends beyonds the saw will be cut off, and thus
another flat side will be given to the peice, and so on, for any other side
or sides; the distance of this guide from the saw will, it is evident, give
the thickness or breadth of the peice thus cut, and the same distance

page_text: being preserved, any number of peices may be cut exactly to the same
thickness or breadth.
To cut a peice taper or wedge fashion. Provide a wedge of the
degree of taper required; apply this wedge to the longitudinal guide,
then, applying the peice to the other side of the wedge, shove up peice
and wedge together, as you would the peice alone to cut it parallel-
wise; this contrivance may equally be applyed to the up and down saw.
Where a very thin saw is employed in roughing out a peice, there is a
case in which its thinness, though supported by guides, like those to
the up and down saw, might render its work less true; this is, where
the quantity of matter it has to detach in different parts of a cut is so
unequal as that on one side, having here and there nothing to cut off,
it would be thrown off to that side and bent out of its course by the
inequality of resistance. To obviate this danger, the flanch on that side
may be made to extend nearly to the root of the teeth, at which place
it should be champfered off to nothing, so as by the inclination of its
surface to wedge off, as it were, and so bend or break whatever it finds
on that side. Where the diameter of such a saw is considerable, the
saw, instead of being of one peice, may be more advantageously com-
posed of annular segments fastened on the face of the flaunch.
To make in any peice a cut of a given depth, which shall not go
through, and which I call a score, you have only to adjust to the depth
required the height to which the saw through its slit projects above the
bench, which is done by making either the bench or the spindle so as
to rise or lower at pleasure. If after having given any such cut which
does not go through the peice, you turn the peice, so as to give it another
cut, meeting and making an angle with the former cut, you may thus cut
out a portion of the peice altogether, leaving in it the sort of channel
which is called a rubbet; by cutting out on different sides two such
rabbets you may leave between them a projecting part, such as is called
a tongue; and a tenon is at the end of a peice, the same thing as a
tongue on the side.
To cut a parallel siding groove or channel you have only to make
the circular saw, or (to use the name I call the tool by, wherever its effect
depends upon a degree of thickness greater than what is necessary to

page_text: give it strength) the circular cutter, of the thickness requisite to form
the breadth of the groove, the depth being determined, as before, by the
height of so much of the cutter as projects above the bench. If the
groove is to be dovetailed the cutter must be conical at its circum-
ference, that is, the cutter, instead of being square at its edge, must
bevel according to the angle of the dovetail, and the bench or the
spindle must be inclined, or the peice so supported as that its under
surface shall be parallel to the outer edge or circumference of the
cutter. If the peice be now advanced against the cutter one side of
the dovetail groove will be formed; to form the other, the peice must
be reversed end for end and shoved along as before. Another mode of
cutting out dovetail grooves may be by a mandril turning in a collar,
and at the end of it furnished with a conical cutter, the diameter of
which at the furthest end shall be equal to the breadth of the dovetail,
and the sides bevelling according to the angle of the dovetail. Suppose
the mandril to be placed perpendicularly, for example, in which case
the cutter itself will be horizontal, with its base parallel to the bench;
let that end of the mandril at which the cutter is be uppermost, the man-
dril being let through, and the cutter projecting above the bench and
raised to such a height above it as the depth of the dovetail channel to
be made requires; the peice now lying flat on the bench, advance it
against the cutter, and a dovetail channel will be cut at one operation.
It is evident that in this way, whatever be the breadth and length of
the groove or channel to be cut in a peice, so much of the stuff, by the
removal of which the channel is formed, is consumed, and the broader
the channel the greater the resistance the cutter meets with and the
greater the forse which is required to make it act. To save as much
as may be of this force will be an object in every case, and so it will be
to save the stuff where it is of a dear sort, and the breadth of the
required channel considerable. To effect both these savings, instead of
a thick conical cutter put on the same mandril, a thin saw forming the
base only of the cone; to this thin saw there must of course be a man-
dril for it to turn upon, which mandril must have some means of
making its way through the peice along with the saw itself, which is
mounted on it. This passage may be made by either of two expedients:

page_text: one is, to give to so much of the length of the mandril as enters the
wood a power of making its way through, for instance, by fluting or
forming it into sharp leaves and thus making it into a cutter in that
part; the other expedient is, by a previous operation, to form for the
reception of the mandril a preparatory groove. It is evident that the
narrower this preparatory groove or channel the greater the saving will
be in point of stuff and in point of force; on the other hand, the
narrower it is the weaker the mandril, and the greater the danger of its
not being strong and siff enough to support the saw which turns on it.
To obviate this danger the mandril may be supported by a bar of
metal, which by a perforation transverse in respect to the length of the
bar, encloses the mandril up to the very saw, and thus forms as it were
a continuation of the collar; this bar may be of any length, provided
only that its thickness and direction admit of its being received into the
preparatory groove as the peice is advanced against the saw. The
bottom of the groove or channel being thus cut, the saw kerfs forming
the sides of it may now be made according to the angle required, and
two bars or slips will have been cut out entire, one on each side of the
preparatory groove, or these two side cuts might have been made at
the same time with the middle or preparatory groove. A saw or cutter
working in this manner at the end of a mandril within the substance of
a piece may be called a root cutter. By a root cutter of this sort a
T shaped channel, used in some cases, particularly in metal, instead of
a dovetail groove, may in this manner be formed at once.
Cutting of mouldings.-If the circumference of a circular cutter be
formed to the shape of any moulding and projecting above the bench
no more than necessary, the peice by being shoved over the cutter will
thus be cut to a moulding corresponding to that of the cutter, that is,
the reverse of it, just as a plane iron cuts its reverse; accordingly, teeth
of such cutters may be considered as so many plane irons. If a à plain
cutter, such as that above spoken of for cutting a groove in the breadth
of a peice, be made so thick, or, as we might be apt now to say, so
broad or so long, as to cover the whole breadth of the peice, it will pre-
sent the idea of a roller; I accordingly call it in this case a cutting
roller: it may be employed, and in many cases with great advantage,

page_text: to perform the office of a plane. The recollection of what has been
said of the manner of producing a waving or winding surface by a
rectilineal reciprocating saw may be sufficient to suggest the means
by which similar effects may be produced, in much greater variety, by a
rotatory cutter, broad or narrow, plain or formed to a moulding. I shall
speak only of the cutting roller; it will be easy to apply the observa-
tions to the other cases. If a roller of this sort be placed with its axis
horizontal, and the bench underneath it be made to rise and lower, the
bench may be very readily adjusted so as to determine the thickness to
which a peice so will be reduced by being passed under the roller. It
is to be observed, that where the track of the peice is under the roller,
the influence of the rotation on the advancement of the peice is the
reverse of what it is where the track of the peice is above the roller;
therefore, if you choose that the advancement of the peice should,
instead of being performed in a direction the same with that of the
rotation, be performed in the opposite direction as before, the direction
of the rotation must be reversed. Whether the axis of the roller be
horizontal, perpendicular, or oblique, the peice by being passed against
it so as to receive its figure, may be made to receive not only a flat
and even surface, but any longitudinal curvature or waving by a com-
pound motion, the bench, during the advancement of the peice,
approaching and receding from the cutter; and, by given at the same
time a tilt to the bench or to the roller, any degree of winding may
be given to the surface of the peice. To gain time cutters may be
applyed to different sides of a peice at once, and such of them as make
parallel cuts may be mounted on the same spindle; if the cuts meet, a
peice of given depth may be slit by cutters of but half the diameter
that would otherwise be necessary.
Formation of saws and other cutters to work with a rotative
motion. The most obvious mode is the making the cutter of one
peice, consisting of steel or iron with steel welded on to it, as far as it
is necessary for strength and sharpness. In some instances, however,
there may be an advantage in making it in peices, for instance, in
annular segments fastened to an included cylinder; the larger it is the
greater will be the advantage in thus composing it, and if a part only

page_text: is worn out or damaged that part may be replaced without injury to the
Another mode of composition is, to make the teeth distinct from
each other, as well as from the cylinder from which they are to project ;
they will thus be seperatly bedded in the cylinder, taking on and
off, as occasion may require. This is a mode I have practised with
particular advantage in the instance of the moulding cutter and the
planing roller above spoken of. For the construction of borers, see
the article of boring.
And, in the first place, boring to any angle, i. e., so as that the axis
of the hole made by boring shall make an angle with the surface at
which it commences.-Provide a mandril lathe with different borers
fitting into it. In a line with the mandril station a bench, capable of
being raised or lowered at pleasure; on this bench fix the peice with
stops and supports in such a manner as to present to the borer the part
to be bored, and that in the direction corresponding to the required
angle. For the borer to perform its office, the mandril may be made
to slide to and from the bench, or on the bench may be adjusted
a sliding bed, on which the peice being held may slide to and from the
borer. A new kind of borer which I make use of consists of a tube
of metal open at the hinder end, the cutting end differently shaped,
according to the work it has to do; for example, like an anger-bit,
center-bit, gimlet-bit, &c. The reason of leaving it open at the hinder
end is, that it may afford passage to the chips, for which reason also,
if it be put to a mandril, the mandril must be a hollow one; so, if the
borer be turned by a handle, the handle can only embrace the outside
of the tube. One advantage of this sort of borer is, that having no
shank or stem to obstruct the passage of the chips it may go through
the piece without being repeatedly drawn out, as an anger or gimblet
must every time the pod is full of chips, for the purpose of clearing it.
Another advantage is, that as it has a smooth cylindrical outside it is
easy to apply bearings of any kind, or even the hand, to guide it at its
first entrance, and it will continue throughout its course to turn
smoothly in the hole it has made. The cutting parts it is most con-

page_text: venient to make seperate, and so to take on and off, for the purpose
of being sharpened or replaced when damaged, as well as that
different kinds may be applied to the same tube or stock, according to
the different sorts of work. The tube itself should of course be as thin
as it can be made, consistently with a sufficient degree of strength, and
the cutting parts should expand as it were a very little beyond the tube,
to clear it for a sufficient passage.
Enucleative or core extractive boring; boring so as to bring out
entire a nucleus or core.-This, when compared with boring in the
ordinary mode, is nothing but the making an annular groove instead
of a cylindrical hole. For small depths the properest instrument,
as being the simplest, is a kind of plough iron, which I call a
circum-ambient bit, turning so as that its cutting end shall describe
a circle; of this bit the edge must of course be adapted to the
breadth, and the stem to the curvature which it is designed the annular
channel shall assume; and for the better discharge of the abraded
matter, without the necessity of drawing out the tool from time to time,
this stem may be twisted or inclined spiral-wise, so as to worm out the
abraded matter as fast as formed. For greater depths, for which
the simple tool above described would be too weak, it may be neces-
sary that the stem should be an entire tube. This tube, that it may
occupy as little of the breadth of the channel, and thereby afford as
little obstruction to the discharge of the abraded matter as possible,
should, however, be as thin as can be made, consistently with the
necessary degree of strength. The edge of the cutter to which this
tube serves as a support, should be of a sufficient breadth not only to
make way for the introduction and advancement of the tube, but to
render the channel so much broader, as that there shall be vacant
space enough in it to receive the abraded matter as fast as it is
detached. This extra breadth should extend, not withinside but wholely
on the outside of the tube, since an equal breadth on the inside would
not contain so great a space. To effect the discharge of the abraded
matter, one mode is, so to form the cutting edge, as that the abraded
matter shall assume the form of a shaving, which being less in thick-
ness than the breadth of the vacant part of the channel, shall as soon

page_text: as formed be turned or twisted a little, so that by lying edgeways and
in the direction, not of a semi-diameter of a ring but of a chord of it,
it may find sufficient room to pass. Another mode is, to furnish the
end of the tube with two or more such cutters instead of one, and
these so shaped and disposed as to cut each of them a portion only of
the breadth of the proposed annular channel, and that portion less than
the portion of the channel left vacant by the thinness of the tube; a
borer of this kind I have seen applied to the boring of water pipes.
In either case, instead of a seperate cutter or cutters, the end of the
tube itself may be cut into teeth like a saw, and those teeth disposed
into two or more concentric rows, of which the outer one only shall
overhang the thickness of the tube. To worm out the abraded matter,
wind about the tube a spiral ribbon, which, that it may leave no part of
the channel unswept, should be of sufficient thickness to fill it up
entirely as far as the breadth of the ribbon extends; in the same view
it should, at the anterior end of the tube, commence as near as pos-
sible to the cutting part. Should the abraded matter be disposed,
by the nature of the material, to stick to the tube, its extension
may be ensured by a seperate spiral ribbon wound round the tube
as before, and advancing with it but not attached to it nor turning
with it; it may either not turn at all, or be made to rotate in the
direction opposite to that of the tube; thus will the whole business
be compleated where the borer is to be of the perforating or pervious
kind, that is, when the excavation is to go through. Where the bore.
is to be of the impervious kind there remains to be made the trans-
verse incision at the bottom of the channel for the extirpation of the
core. For this purpose the tube must be furnished with a cutter or
cutters, made so as to close in upon the core, approaching nearer and
nearer to the center as the tube works round, till they have got so near
and weakened the core so much at the root as to enable it to be
broken off. Suppose a single cutter; in this case, although if the
depth to be given to the bore be considerable this cutter must, for
the sake of strength, be supported by a tube, yet it must project beyond
it on a stem, which stem may be of the same thickness as the tube,
but must be of a breadth not too great to prevent it from being made

page_text: to bend inwards towards the axis, according to the required angle, that
is, the required degree of suddenness in the bend. To reconcile the
better the requisite flexibility in the one direction with the requisite
inflexibility in the other, the stem of this cutter may be made in joints,
curving inwards in a longitudinal direction but inflexible in a lateral
direction. When the stem of the cutter is in one piece, and not in
joints, to favour this centripetal inflection, not only the cutting edge
may curve that way but the stem of the cutter may be so contracted
as to have a tendency to spring inwards. When this cutter is in joints
the incurvation must be given by a separate spring placed on the out-
side of the cutter, and reflected upon it by the reaction of the concave
side of the excavated channel; when once the course of the tool has
received an inclination inwards, that inclination, be it ever so slight,
will, by the advancement of the tube, be continued till the extirpation
is performed. If the diameter of the core be very considerable, in
which case the stem of the cutter projecting beyond the tube must be
proportionably long, a sort of strengthening brace may be applied to
it. This strengthening brace may consist of a slight chain, attached
at one end to the anterior part of the cutter, and at the other to the
anterior end of the tube, at such a distance from the root of the cutter
as shall be found convenient. Where the nucleus, when bored out,
will not drop out of the borer of itself, an expeditious mode of clearing
the borer of the nucleus may be an object of importance; this will be
more particularly apt to be the case where, on account of the yielding-
ness of the substance or the thinness of it, the boring may be per-
formed by the mere sharpness of the tool without the necessity of its
working a passage for itself by abrasure. For effecting the discharge
at the posterior end of the boring tube the tube may have for its stock
a hollow mandril, open, as well as the tube, at the hinder end, and of
a bore ever so little larger than that of the tube; the reaction of a
suceeding nucleus as it forms will then push on the preceding one, in
which case, let the borer with its mandril contain ever so many of
these nuclei, it will discharge itself as fast as it fills. For effecting the
discharge of the anterior end of the boring tube you may make it closed
at the hinder end with a spring, by the reaction of which the nucleus

page_text: shall be discharged as soon as the pressure produced by the advance-
ment of the borer is removed. To effect the discharge by the drawing
back of the borer you may make in the breech of the tube a small
hole, in which you may fix one end of a rod which goes through the
mandril, and by its other end is fastened to the bench; this rod, re-
maining motionless while the borer is drawn back, will prevent the
nucleus from being drawn back with it, and so cause it to drop out.
To give a circular configuration to the outside of a peice without giving
a circular motion to the peice itself, the same apparatus may be employed
as for boring. For this purpose fix the peice on the sliding bed
in the direction required, and, instead of a borer, fix on the mandril a
concave tool adapted to the external figure required to be given to the
peice, so that when the mandril is set in motion the tool shall act on
the outside of the peice as the peice advances.
In this manner round
tenons, for example, may be formed at the end of spokes of wheels,
the spoke being placed on the bed, according to the angle of the
dishing.
For pervious boring, especially where the depth is considerable, I
prefer boring from the two ends or opposite points at once; the diffi-
culty, which increases greatly with the depth, is thus proportionably
reduced. Where there is force enough at command the business is
done in half the time, and both orifices are left smooth; whereas, in
fibrous substances, most sorts of wood especially, without a strong in-
cision previously made at the end at which the borer is to come out,
it is scarcely possible to get it through without breaking out the
stuff. These two opposite borers may each be mounted on a mandril,
and must, it is evident, be so adjusted as that their axises shall lie most
exatly in the same right line. To perform the operation, the peice
being placed on the bench and supported at the proper height
between the borers, the advancement of the mandrils may be either
simultaneous or alternate, continuing till each borer has reached
the middle; where simultaneous, care being taken to apply to each
the proper stops necessary to prevent collision; if alternate, to ensure
the compleatness of the perforation, one or both may be allowed: to
advance a little beyond the middle point. As good a way as any

page_text: against such collision is, to make the stoppage take place between
borer and borer, (for instance, by means of a stopping bar adding
to the stock of each,) instead of making it take place between the
borer and the bench; by this means there need be no difficulty
about making either of them advance beyond the middle line, since
in so doing one will repel the other before the points have come into
contact.
VII. MORTISING OR MORTISE-MAKING.
An ordinary mortise is only a square or oblong hole, pervious in some
cases, impervious in others. For mortising I employ boring as far as it
will go;
there remains the squaring of the hole, of which presently. The
boring bit I usually make use of for mortising is either a simple tool,
like a chissel, of a breadth equal to the diameter to be given to the bore, or
a tool composed at its cutting end of two such chissels, the edges exhibit.-
ing the form of a cross. For a square mortise there needs no more than
to make the bore of a diameter equal, mathematically speaking, to that
of the circle inscribed in the square. For an oblong mortise I make a
bore, the diameter of which is equal to the breadth of the intended
mortise, and in the operation of boring I make the bore traverse from
end to end. The boring tool is accordingly sharpened at the edges of
its leaves as well as at the sides; the rectilineal motion for this purpose
might be given to the borer, but I find it most convenient to give it to
the peice. The boring might be performed by compleating the depth
before you begin to traverse, but I find it most convenient to bore but a
little way in depth at a time and then traverse, advancing the borer by short
steps after each traverse. For strength or expedition you may multiply
the leaves of the borer so as to give it the form of the cutting mandril
above spoken of, except that the mandril does not (like the borer) cut at
its end; but the more these leaves are multiplied the more they will be
apt to clog. The extrusion of the abraded matter may be a little facili-
tated by given to the stems of the leaves a kind of spiral twist. The
borer, instead of being large enough to cover the whole surface and
consume the whole substance of the bore, may be as small as it can be
without prejudice to strength, and thus, by skirting the boundaries of

page_text: the intended bore, cut out, in what I call the circum-ambient method, a
core in the middle. This saving of substance may be extended in some
degree to impervious borers by employing a root-cutting tool, upon the
principal above explained. Having made the circum-ambient channel,
and at one end of the oblong compleated the bore to its depth by an or-
dinary borer, and that of the full size, now, in the room of the borer,
introduce a thin circular cutter or saw, of the same diameter, which, of
course, must be fixed to a cutting mandril, unless the way has been already
cleared for it by a preparatory groove. See article Working by a Rotative
Motion of the Tool. Two peices may in this way be extracted entire, one
on each side of the cutting spindle. It would be endless to enumerate
the purposes for which these various methods of boring may be employed,
and that with more or less advantage, according to the difficulty of the
work, the hardness of the stuff, or the value of the material. Shallow beds
may thus be made with the utmost nicety, for the purposes of inlaying
boxes in ivory, for instance, or any of the very valuable woods, by
excavation, instead of compaction; boxes, troughs, or other excavations
in any kind of stone, as also in metals, where casting or stamping would
either be impracticable or less adapted to the purpose. When the
bottom of the excavation is to be curve shaped, as in fluted work, the
end of the borer must, of course, be adapted to the curve.
In mortising
wood or other materials it is common enough to employ boring for
getting out part of the stuff, but then it is performed by hand, and at
random, and without the benefit of stops or guides, much less of the
traversing, the circum-ambient, or the root-cutting method above de-
scribed. The mortise or excavation being as yet left rounding at the
corners there remains the squaring of it. In the case of pervious
mortises one sort of tool for this purpose is a rasp or file, with a smooth
stripe on the cutting surface, occupying the middle part of its breadth
and running the whole length; on each of its sides it is uniformly
smooth, and the breadth from side to side is such as exactly to fill up
the mortise. The stuff of the rounded corner on each side being con-
sumed by the two rough stripes, one on each side, the further progress
of the abrasion will be stopped by the smooth stripe that lies between
them, whereby the tool will be prevented, as it is intended to be, from

page_text: advancing beyond the tangent to the circle; the tool may have its
opposite sides similar, so that when one end of the mortise has been
squared the other end may also be squared without taking out the tool.
This mortise-squaring file may be worked either by hand or with the
aid of mechanism. In the latter case it may move to and fro in a fixed
channel, in the manner of the reciprocating saw, one end capable of
being disconnected from its steadiments, for the purpose of being let
into the mortise, or the steadiment may be made strong enough at one
end to supersede the necessity of adding the steadiment at the other;
advance now the peice against the tool, first on one side, till the squaring
is compleat, then on the other, and the business will be done. Another
sort of tool for squaring a round-ended mortise is a stamping chissel.
Of this squaring stamp the stock must, as in other stamps, be
confined to its course, whatever it be, vertical or in any other direc
tion, by fixed channels. To be co-extensive with the curvature to
be squared, the chissel should be hollow, in the form of the half of a
hollow square.
A pair of such chissels for each end of the mortise
may be made to fit into the same stock, so as to act at once, by
inserting between them middle peices of different breadths, according
to the length of the intended mortise.
A stamping apparatus, in other
respects the same, may be made to serve for mortises of different
lengths. For the same reason that the boring should be performed
from both ends or sides so should the squaring be. It may be per-
formed either by a single stamp, the peice being turned upside down
for the purpose, or by a pair of stamps made to work in concert in
opposite directions, either simultaneously or alternately. A third sort
of tool that may be employed for this purpose is what I call a rasping
punch; this is a strong thick tool of which the lower end (viz., that end
which is to be the first to enter the mortise) is of the same shape and
size as the mortise is of before it is squared, and the other of the same
shape and size as the mortise is to be of when squared. This con-
figuration changes gradually from the one shape to the other, from end
to end. The tool, to enable it to make its way, is cut its whole length into
teeth, in the manner of a rasp, file, or saw. The length of the tool, that
is, the slowness of the change, should depend in some measure upon the

page_text: hardness of the stuff' which it is to abrade. A rasping punch of this kind
may be made either in one peice, and that of the size of the intended
mortise, with a cutting part for each end of the mortise, that is, on each
of two of the four sides of the tool, or in two peices, for the purpose of
adapting it, as in the case of the chisel, to mortises of different lengths,
by the insertion of a middle peice. For impervious mortises the
squaring, it is evident, cannot be performed by the file. For the
vertical cut the squaring chisel will serve in this sort of mortise as
well as in the other; but there remains the horizontal cuts necessary
to meet the vertical ones and complent the extirpation. These hori-
zontal cuts may be performed by two equal and similar chissels, which
I call root-squaring chissels. Each chissel consists of a horizontal and
an almost upright bar, joined to the horizontal one at an angle a little
less than right angle; the breadth of the horizontal bar is exactly equal
to that of the mortise, at least at the cutting edge. To perform the
operation these chissels are placed in the mortise back to back, exactly
at the middle line of the length of the mortise, a narrow wedge-shaped
space will then be left between them. A wedge now, of the proper
thickness, adapted to the length which they are to cut, being introduced
and forsced in between them, the operation will be performed. In soft
substances, such as wood, for example, the vertical cut will have been
sufficient, and the operation of squaring may accordingly be compleated
at a single stroke. In harder, such as metal, for example, or even
ivory, &c., repeated strokes may be necessary, though still the hori-
zontal cut may be dispensed with. For this purpose a chissel, cutting
one end of a mortise at a time, may be worked by a reciprocating appa-
ratus, the peice being advanced against the chissel, in such a manner
that but a small part shall be cut off at a time. Where the mortise is
to enter the peice obliquely it is evident that either the peice or the
tool must have a tilt, according to the angle. A squaring chissel,
mounted as above, may be employed, instead of the boring apparatus,
for lengthening the mortise; but as the boring apparatus must be
employed in the first instance there seem few cases, if any, in which
such substitution would be attended with any advantage. Some few
instances, however, there may be, in which the excavation may be
E

page_text: -performed by the stamping.chissel alone, .without any boring; one
is, that of mitring a sash-bar. This operation may be considered as
divided into two, consisting of a perpendicular incision, to the depth of
the mitre, on each side of the bar, and an incision on each side, in a
transverse direction to the former, compleating the excavation. For the
first operation I employ a stamping tool, composed as it were of two
chissels, crossing each other at right angles, which I call the scoring
cross; for the other, a pair of chissels, separate from each other, but
which I call the root-cutting chisels, or root cutters. The marking cross
would resemble in its form one of the borers I use for mortising, were
it not that the arms of the cross, instead of being in the same plane
with the center or point of intersection, must of course, extend below
it, according to the slope of the sides of the bar which they are to
stamp. To these root cutters, as well as to the scoring cross, I give
channels, to determine the direction of their motion, and stops to limit
performed by the stamping .chissel alone, .without any boring; one
is, that of mitring a sash-bar. This operation may be considered as
divided into two, consisting of a perpendicular incision, to the depth of
the mitre, on each side of the bar, and an incision on each side, in a
transverse direction to the former, compleating the excavation. For the
first operation I employ a stamping tool, composed as it were of two
chissels, crossing each other at right angles, which I call the scoring
cross; for the other, a pair of chissels, separate from each other, but
which I call the root-cutting chisels, or root cutters. The marking cross
would resemble in its form one of the borers I use for mortising, were
it not that the arms of the cross, instead of being in the same plane
with the center or point of intersection, must of course, extend below
it, according to the slope of the sides of the bar which they are to
stamp. To these root cutters, as well as to the scoring cross, I give
channels, to determine the direction of their motion, and stops to limit
the extent of it.
VIII. TURNING IN A LATHE.
In some cases there may be a convenience in employing a double
lathe, composed of two mandrils, like those spoken of under the article
of Boring; each mandril being furnished with a proportionably closing
chuck, of one of the kinds spoken of further on under the head of
Adjustment and Steadiment, the two mandrils being thereby adapted
to lay hold of each of them; or the face of the chuck, being flat, the
stendiment may be given by a degree of penetration, resulting either
from general roughness or from rows of pins, or ridges, or scores, like
those on a rasp or file, radially disposed. In this case it will be con-
venient that one of the mandrils should be made to press up towards
the other by a weight or spring, strong enough to steady the peice.
In some cases it may be convenient to give simultaneous motion to
the mandrils; this may be done by furnishing each of them with a
cog wheel, working in two similar cog wheels, fixed on to a sepa-
rate spindle. In other cases a pair of chucks, of either kind, may
be fixed previously to each end of a peice to be turned, and these
chucks may, instead of being afterwards fixed. on the mandril, be

page_text: furnished with only a plain center, of the male or the female kind,
at the back of each, adapted to the center pins of a lathe.
The
peice may by this means be instantaneously applied to any ordinary
lathe, and that without being penetrated or so much as touched.
by the center pins of the lathe. For the more readily presenting
a number of similar peices in procession to a turning lathe the
following contrivance may be employed :-Where a peice is to be
supported between the center pins of an ordinary lathe, or between the
mandrils of a double lathe, then, if the peice be of any regular figure,
prepare a moveable bed for it to lie in, in such manner that the centre
of magnitude of each end of the peice shall be in the direction of the
centres of the lathe. Give the peice then whatever support it requires
in the lathe, and having so done move the bed out of the way, so
much as is necessary to prevent its obstructing the rotative motion of
the peice, but let the bed be so fitted to the lathe as that it may be:
instantaneously replaced in exactly the same position, for the adjust-
ment of any similar peice. If the peice be square or circular, that
is, if a transverse section of it, made at right angles to the axis, be a
square or a circle, let the bed be made in the shape of a V, the arms
of which form a right angle; so that by sliding up and down to and fro
from the center of the center pin, it may be made to serve for square
or circular peices of various dimensions, and that without any other.
variation than adjusting the height of the bed to the diameter of the
peice. A bed of this sort I call a presenting bed. The turning a
number of peices exactly of the same figure may be facilitated by
enabling the tool to receive a more effectual guidance from the rest..
If the length of the peice to be turned comes within the compass
of the breadth that can conveniently be given to the tool, then, having
ready any tool adapted to the figure required, let there be a channel for
the rest, in which channel the tool may slide up towards the peice
till the work is finished, a moveable stop being adjusted on the tool
80 as to prevent its. being shoved too far. But if the peice be so
long as that the tool must, in order to enable it to compleat its work,
be moved along the peice; provide a rest extending the whole length of.
the peice, in which rest make along. its whole length a channel, con-

page_text: formable to the general external figure (whether strait or curved)
which the peice is to be of when finished, no regard being had on this
occasion (for reasons that will hereafter be seen) to small identures or
projections. Let there, moreover, be a block, with two equal round
pins projecting from the under side of it, each of them fitted into the
groove of the rest, so as to slide in it without shaking. In this block
let the tool slide up to the peice, through a groove or mortise, with a
screw through the top of the mortise, to fix it at any part of its course,
and with a stop or shoulder, to prevent its being advanced too far. The
tool may, in that part of its edge which is to be first presented to the
peice, be adapted to cutting away the roughest part, in the other part,
to the smoothing of the work, and these two parts of the tool it may
be convenient should be separable from each other. Apply now this
tool to one end of the peice, and as the peice turns let the tool advance
along the channel in the rest. The peice will thus receive its configu-
ration, according to that of the channel, supposing no sharp projection
to be included in its figure. If, on the other hand, any such projection
is to be left, a stop must be provided for stopping the tool at that part
of the rest; at this period let the tool be drawn back through its mortise,
and when it has passed the place of the projection it may be advanced
again up to its shoulder, and the operation continued as before. To
finish any such projection, provide, as before, at that part of the rest, a
fixed block, with another tool on it, sliding up to the work through
a mortice or channel; and so in case of a cavity, or any number of
cavities or projections. For turning long and slender articles, besides
the channel already described for the guidance of the tool, let there be
on the other side a corresponding channel, in which moves a slider,
similar to the one employed for the application of the tool; to this
second slider fix a support, which is to be made to keep pace with
the tool, keeping only so much behind as not to touch the peice,
except where it has already received its figure. Instead of a simple
cutting tool sliding in a channel, as above, a circular cutter may
be employed, turning. upon its axis; and for hard substances, such as
hardened steel, or stone, or any other substances that are best wrought
upon by grinding, may be employed grindstones, laps, or any other of

page_text: the instruments best adapted to the nature of the substance. If certain
parts of the same peice, or the whole of it, be required, instead of being
round, to be of any number of sides, and yet of a figure corresponding
to that of the channel in the rest, keep the peice stationery in the lathe,
instead of keeping it turning, and the sides may be successively formed
by a simple cutter, like a plane or chissel, guided by the channel as
before, each side being formed either at one stroke, or by repeated
strokes, according to the nature of the case. Or, instead of a cutter of
the sort just mentioned, may be employed a circular cutting or grinding
instrument, turning on a spindle which plays in a support, which sup-.
port slides in the channel above spoken of. By the introduction of a
dividing plate and index the number of the sides may be determined
at pleasure; in this way, similar polygons may accordingly be worked.
Instead of guiding the tool in its motion along the peice, as above
spoken of, by a fixed channel or otherwise, another mode is, to make
the lathe itself, with the peice suspended in it, to reciprocate or traverse
longitudinally, the tool remaining stationary. This longitudinal motion
may be either straight, waved, or otherwise curved. A tool with a
rotative motion may be equally applied to the cutting of skrews of
all sorts and sizes, and in all variety of materials. For the cutting of a
skrew, or nothing more than the cutting a channel or furrow in a
spiral form, with respect to making the peice move on as it turns
about its axis, according to the angle of the spiral, the modes already
in use in screw cutting may be employed. Adapt the edge of a cir-
cular cutter to the shape of the thread or spiral channel, and adjust the
spindle of the cutter to the angle of the spiral, give then a quick motion
to the cutter while the peice is turning gently round in the opposite
direction, at such a rate as to give time for the cutter to clear its way,
and the skrew will be compleatly cut as the peice advances.
operation may in some cases be facilitated by employing before, or even
instead of, the above cutter, two thin cutters or saws, so adjusted as that
their kerfs shall meet, and thus take out an angular spiral slip entire
the whole length of the skrew. If the peice in which the skrew is to
be cut be as yet in a rough state, it may be brought to shape and the
skrew cut in it at the same time; the cutter being so shaped as that,
The

page_text: while one part of its breadth forms the ridge, another shall cut the
furrow. For cutting taper skrews of all sorts, and fusees for watches,
clocks, &c., circular cutters may very advantageously be employed;
all you have to do is, to make them advance to and recede from the
axis of the peice, according as the taper or shape requires. If while
the peice rotates without advancing you present to it at the proper angle
a long straight knife guided by a channeled rest, upon the principal of
that above described, or otherwise, the combination of the two motions,
the rotarory with the longitudinal, will produce the drawing stroke
necessary for the cutting cork and other soft and elastic substances.
In this case, that the business may be done at one stroke, so that the
tool shall finish as it goes, the rotative motion of the piece should .be
derived from the longitudinal one of the knife, and the knife should be
long enough to apply itself during the whole course of the operation
to the whole of the length of the peice.
IX. ADJUSTMENT AND STEADIMENT.
Throughout the whole system of the operations above delineated the
accuracy of the work, as well as the expedition with which it is per-
formed, will depend in a great degree on the exactness with which the
peice is placed in the position in which it is to undergo the action of
the tool, and the firmness with which it is fixed there, especially where
a-number of peices are to receive similar configurations, in which case
the exact similarity will depend on the exactness with which their
respective positions successively coincide. One way of adjusting the
the position of a peice would be by lines traced on its bed, and this is
the only mode which is of a peice with common practice; but for
working to similar shapes a much more suitable and advantageous way
is, to prepare stops and supports, so placed on the bed or bench as that
every one of a number of similar peices, when applied successively
against these stops, shall unavoidably have been brought into the same
position. Besides the great advantage which, when the similar peices
are numerous, is gained in point of expedition, the accuracy of the work
is by this means rendered independent, in good measure, even of
attention and altogether of dexterity. The contrivance and arrange-

page_text: ment of these stops, according to the figure and dimensions of the
peices to be worked, as well as the most eligible modes of steading the
peice in its position, are what an experienced mechanic can be. at no
loss to accomplish. For some purposes I find it convenient to have
pins or studs, projecting from tongues, sliding in grooves cut in the bed
or bench, so as to be stationable by means of screws or wedges.
Sometimes it will be convenient to have the stops fixed for only one
end and one side of the peice, while the opposite ones are made move-
able; such a moveable stop may then consist of a screw or wedge,
acting so as to open for the purpose of receiving the piece, and close in
again with a forse sufficient to hold the peice steady enough to resist
the action of the tool.
How to present the same determinate parts of a number of similar
pieces successively to the action of the tool :--1. Where the intended
stations are disposed along the length of a peice. In this case fix the
peice on a sliding bed in such a manner as to be moveable in the
direction of its length; let the sliding bed be furnished with a stop, in
the form of a pin or bolt, projecting, for example, from the side to be
inserted, or to drop of itself into holes or notches in the bench, one for
each of the positions required. Or, instead of being made in the bench
itself, these holes or notches may be made in a peice of wood or metal,
moveable in a groove or otherwise, along the course which the sliding
bed is to take. In this way similar peices may, at equidistant or other-
wise correspondent points of their respective lengths, be exposed to the
action of a borer; for example a saw, a file, or any other tool adapted to
the hole, incision, or mark which they may be intended to receive. If,
as in the above described method of making oblong mortises, for
example, it be required that when arrived at any one of the proposed
stations the peice, instead of being absolutely fixed at that station,
should, in order to receive a perforation or incision so much the longer,
move to and fro within certain limits, the purpose may be effected by
giving a correspondent extent to the notch or hole within which the
pin or other projection is, for this purpose, to be allowed to traverse.
2. Where the intended stations are disposed along the transverse
dimention of the peice. In this case the simplest way, if circum-

page_text: stances will admit, is to lay the piece successively upon its different
sides, its position, in respect of its length, being all the while preserved
by stops applying themselves at each end; but under other circum-
stances, particularly in the instance of circular peices or many-sided
peices approaching to circular, it may be more convenient to give the
peice such a mode of support as may allow it to turn freely upon its
axis, for the purpose of being connected with the dividing plate, into
which a stop may be inserted by means of holes corresponding to the
station required; thus the nave of a wheel, for example, may be sup-
ported by poppets projecting from a sliding bed while the mortises are
cutting in it for the spokes; thus, again, a pillar, for example, may be
stopped for fluting, or a rough log, for being formed into a regular
polygon, supported on the slider of a saw frame.
How to hold successively, between two supports, peices of various
dimensions, in such manner as that the middle of each peice shall suc-
cessively be adjusted to the bed in the same position:-For example, I
make two opposite stops or supports moveable towards each other, and
connected in their motions in such manner as that one cannot advance
without the others advances towards it an equal distance in the same
time. If, instead of the middle, it be any other proportionable part
that requires to be brought into a certain position, any such variation
of the effect may be produced by only adjusting the simultaneous mo-
tion of the supports, according to the proportion required. Suppose,
for example, one of the supports is made to receive a motion always
twice as great as the other, then, whatever be the breadth of the peice
which is held between them, the imaginary line dividing that peice into
thirds will be brought to the same position on the bed. A number
peices may successively be held breadthways in this manner, upon a
sliding bed, for the purpose of being advanced, for example, against
a saw, in order each of them to receive an incision in the middle, or
in any proportionate part, in order to be formed into a tenon at the
end; thus, again, may a number of sash bars, of ever such different
breadths, be successively brought into positions in such manner that
the middle line of each shall coincide exactly with the center or point
of intersection of the squaring cross. See above, article Mortising.

page_text: If the peice require to be adjusted depthwise also, then another such
pair of supports may be made to embrace it in that direction; thus,
for example, a number of peices of various dimentions may each of
them, at the middle or any other given part of either of its extremities;
be exposed to the action of a borer. A third pair of such propor-
tionally-closing supports may, by embracing the peice endways, com-
pleat the similarity of adjustment in all directions. The business of
making the opposite stops move to and from each other, as required,
is what may be, accomplished in any one of a variety of ways;
by two screws, for example, turning in concert, in fixed nuts, pointing
towards each other, or by one double skrew, of the sort called a
right and left handed skrew, on which two nuts, one on the right-
handed the other on the left-handed part, are made to approach
towards or recede from each other by turning the skrew one way
or the other.. I have never heard of the threads on such a skrew
being made any otherwise than of an equal inclination, the nut
on the right-handed part moving consequently the one way, as far
as the nut on the left-handed part moves the other way but it is
plain that by a difference in the inclination of the two threads the nuts
may be made to move in different proportions, and that according to
any difference that may be required. Wedges acting against supports
stationed on each side a peice may, by being advanced. equally and
simultaneously, be made to produce the same effect; the lengths of the
wedges and the quantities of their respective longitudinal advancement
being always made equal, the proportions in which they respectively
close in upon the peice will be regulated by their respective breadths
or thicknesses. If it be required that the same wedge shall move a
support backwards as well as forwards the connection must be effected
in such manner as not to impede the sliding, for example, by a dovetail
or T shaped tongue and groove; in some cases the effect of a wedge
may be produced to more advantage by the application of a pin to an
inclined slit. Where the motion to and fro of these supports is to be
extendible to greater lengths, the effect may be produced by two racks
moyed parallel to each other by a common pinion or cogged wheel
placed between them, one rack being on one side the axis of the pinion
F

page_text: or cogged wheel, the other on the other side. Where the peice must, for
example, on account of its great length, be held by several such closing
supports situated at different parts of its length, matters may easily
be ordered so that these supports shall all of them be put in motion at
once. If for this purpose wedges or levers be employed, a simple bar
connected with these wedges or levers will produce the simultaneity
required. If skrews are employed a small wheel to each will enable
all to be turned at once by a racked bar. In this case any proportional
difference required to be made in the advancement of the supports may
be accomplished either by a difference in the diameter of the cogged
wheels by which the screws receive their rotative motion, or by a
difference in the inclinations of the threads of the skrews. Thus by
differrent skrews unequal motions may be given to any number of sup-
ports although their respective motions be received simultaneously, and
that from one and the same bar. Thus by means of wedges moving in
concert, or skrews, or racks, not only may peices of any shape be pressed
in as many parts at once as may be required for any purpose, but the
business of simple adjustment without pressure may be effected in a
parallel or any other direction by a simultaneous motion of stops or
supports. So a bench, for instance, may be raised at once by means of
supports, in such number and such situations as to insure its position in
a horizontal direction, or any other. So, for example, the guides used
to the sawing apparatus may be adjusted according to the breadth of
the peice to be sawed, and thus the borers and other tools may be
advanced to act simultaneously on the peice.
How to make any number of supports move equally to and from a
center:--For this purpose arrange in a circular ring as many skrews
as you please, all pointing towards the center, and furnished each with
a small cog'd wheel, so that a circular cog'd wheel, bar, or ring,
acting at once upon all those wheels, by being moved one way, makes
all the skrews advance towards the center, and by moving the other
way makes them recede from it. Upon this principle I have made
chucks for turning lathes with different numbers of supports, so as to
embrace a circular or polygonal peice on all sides at once, and that in
a situation exactly concentric with the axis of the mandril; I have also

page_text: produced the same effect by a circular bar or ring of wedges acting
upon the outer ends of the supports. When any number of peices are
to be put together in a circular form, for instance, the component parts
of wheels, the staves of casks, &c., a contrivance of this kind may be as
useful to bring the parts together, by uniform pressure into form, as to
hold them in that form afterwards, for the purpose of being turned or
otherwise worked. It is plain that all these contrivances for pressing
and laying hold of the outside of a peice by contraction may be equally
adapted to the acting on the inside of a hollow peice by distension. In
this way a chuck may be made an universal chuck of the male kind as
well as of the female. A chuck on this principal may be made to take
in peices of as great a difference in diameter as can ever be required.
For this purpose the supports in question should be in the form of
sliding bars, moving in grooves or channels cut in the face of the chuck
and pointing in the form of radii towards the center; these sliding bars
may themselves be flush with the face of the chuck, and when pressed
up they may extend as near to the center as their breadths at that end
will admit, at which part, too, they may be tapered away for the purpose
of being enabled to close in upon the smallest peice. Outwards, these
sliding bars may be enabled to extend as much beyond the chuck as
the dimensions of the peices to be held may require. For laying hold
of a peice of any size, from the smallest to the greatest, to which the
sliders can extend, let them be furnished throughout their whole length
with ranges of equally distant pin holes; then, for supports to the
peice, insert stout pins into such of the equi-distant holes as correspond
the nearest to the dimensions of the peice, and on giving motion to the
sliders the piece will be embraced as required. For many purposes a
chuck of a more simple construction
suffice; it
may
may be furnished,
on its face, with one pair only of equally moving supports, especially
if the supports are furnished each with a pair of equi-distant and similar
horns, so as to support the peice at four points. For other purposes
there may be two pairs of supports, moving each pair separately towards
the center and at right angles to each other.

page_text: ✗. ADVANCEMENT, VIZ., OF THE PEICE TO THE TOOL, OR OF THE TOOL TO
THE PEICE.
For the case where the motion by which the work is performed is of
the reciprocating kind, instructions have, under the head of Sawing by
a Reciprocate Motion, but given by reference to present practise.
When the motion is of the rotative kind, though the advancement may
be: performed by hand, yet regularity may be more effectually insured
by the aid of mechanism. For this purpose one expedient is, the
connecting, for instance, by cogged wheels the advancing motion of the
peice with the rotative motion of the tool; another expedient is, em-
ploying a power so as to gain purchase, in which case the facility of
insuring regularity will be according to the quantity of purchase gained.
For short distances this may be done commodiously enough by a lever
or a screw, but where the advancement is to have a long range the
rack and pinion is more convenient, a rack, for example, being fixed to
the sliding bed in a direction parallel to that of its motion and the
pinion which moves it turned by a wynch. Or, instead of the action
of the hand, a weight may be employed, or, for very short spaces, a
spring.
XI. CLEARANCE, VIZ., CLEARING AWAY THE CHIPS OR OTHER ABRADED
MATTER.
In some instances provision is made for this object in the configura-
tion given to the tool itself, see article Boring, in others separate
contrivances may be requisite. After boring, sawing is the operation
which, from the nature of the tool, is most exposed to the inconvenience
of clogging; this, therefore, appears to afford the fittest example of the
expedients that may be employed for the purpose of clearance. Whether,
even in this case, any expedient for this purpose will be worth applying
will depend upon circumstances, viz., upon the shape and magnitude of
the spaces between the teeth, and upon the quality of the substance
sawed. Where a slight power is sufficient for the purpose of clearance
it may be afforded by
a blast of air. Any workman will know how to
apply the nozzle of a pair of bellows to blow for this purpose against

page_text: the teeth of the saw; the bellows, it is evident, may be played either by
the
power that works the saw or by any other power, as convenience
may dictate. In cases where air would be ineffectual, as in the
instance of a wood abounding with turpentine or any other adhesive
rosin, a solid instrument must be employed to perform the office of
a brush, not that it is necessary that the substance of it should, as
in a brush, be flexible. Of this clearing tool the form may be
that of a thin cogged wheel, the spaces more extensive than the
cogs, the position transverse to that of the saw, and so near
for the cogs of the wheel to enter between tooth and tooth of the saw,
the motion derived from and connected in such manner with that
of the saw, that not only each cog shall pass between tooth and tooth
of the saw, but each tooth of the saw between cog and cog of the
wheel;
and whether the sawing apparatus be of the rotatory or reci-
procating kind the form of the clearing tools may be still the same.
As to the derivation of the proper rotative motion of the clearing tool
from the rotative motion of the circular saw, or from the reciprocating
motion of the reciprocate saw, it need not be particularized, being one
of the most common operations on mill work. Where the saw, being
of the rotative kind, works above the bench, the clearing tool, in order
to be out of the way, will naturally be placed below the bench. Where
the saw is of the reciprocating kind, as some of the teeth come out
on one side, say the upper side of the peice, others on the other, say
the lower side, there must accordingly be two such clearing tools, one
above the peice the other below it. It follows that for the saw to
have all its teeth cleared in this way, the length of the saw must be
such as that, partly on one side, partly on the other, all the teeth shall
come out of the peice for the purpose of meeting the action of the
clearing tool. If the rotation of the clearing tools be produced imme
diately from the reciprocating motion of the saw it will be-vibratory,
turning one way as the saw ascends and the opposite way as the saw
descends, by which means the brush will pass and repass between the
In the case
teeth within the period of such reciprocation of the saw.
of the reciprocating saw, instead of the circular sort of clearing tool,

page_text: may be employed a longitudinal one, in form of a rack or cogged bar,
placed in front of the saw, the cogs alternating with the teeth of the
saw and sweeping the spaces between them in the manner of a comb;
upon the arrival of the saw at the greatest height, one of these combs
clears the upper half of it, as upon the descent of the saw to its
greatest depth another does the lower half. The accuracy with which
in all these several cases the projecting parts of the clearing tool adapt
themselves to the spaces between the teeth of the saw, instead of
running foul of the teeth themselves, will depend upon the nicety of
the connection between the motion of the tool and the motion of the
saw,
and need be no greater than what is commonly exemplified in
mill work.
The several modes of working above spoken of are the fruit of my
own Invention, matured more or less by own practise. The descrip-
tion I have given of them is such as, according to the best of my
judgment, would be sufficient to enable any man that chose it to put
them in practise to advantage. In some of the instances the con-
trivance is no more than what any intelligent machanic conversant in
the particular branch of work which it is calculated to facilitate, may,
by help of these instructions, be able to execute for himself, for the
purpose at least of that particular branch of work. In others, espe-
cially where the Invention is such as to comprise a new and entire
machine, the assistance of a millwright, or engineer by profession,
whose business implies an acquaintance with machinery in general,
may require to be called in. These several Inventions I accordingly
claim the exclusive right of exercising, and that in all the variations of
which they are susceptible, and in respect of all sorts of materials to
which they are susceptible, saving such variations in which, and such
materials on which, they may have already been practised by others
without my knowledge. As to the mode of giving motion to any of
the above machines, in addition to the modes in common use, one may
be, the putting the machine, if not too bulky, into a carriage and
deriving the power from the rotation of the wheels on which the
carriage runs; in this way, besides the advantage of portability, the

page_text: .
ower of horses or other beasts of draught may be applied at an
xpense less than that of erecting a horse mill.
In witness whereof, I, the said Samuel Bentham, have hereunto set
my hand and seal, this Twenty-third day of April, in the thirty-
third year of the reign of our Sovereign Lord George the Third,
by the grace of God of Great Britain, France, and Ireland, King
Defender of the Faith, and so forth, and in the year of our Lord
One thousand seven hundred and ninety-three.