IMPROVE- MENTS IN JOINERS' CLAMPS
Year: 1873

page_text: LETTERS PATENT to William Henry Goodchild, of Bayonne, Hudson
County, State of New Jersey, United States of America, and
Samuel Francis Hay, of Brooklyn, King's County, State of New
York, United States of America, for the Invention of "IMPROVE-
MENTS IN JOINERS' CLAMPS."
Sealed the 5th September 1873, and dated the 19th March 1873.
PROVISIONAL SPECIFICATION left by the said William Henry Good-
child and Samuel Francis Hay at the Office of the Commissioners
of Patents, with their Petition, on the 19th March 1873.
We, WILLIAM HENRY GOODCHILD, of Bayonne, Hudson County,
State of New Jersey, United States of America, and SAMUEL FRANCIS
HAY, of Brooklyn, King's County, State of New York, United States
of America, do hereby declare the nature of the said Invention for "Im-
PROVEMENTS IN JOINERS' CLAMPS," to be as follows :-
Reference is had to the accompanying Drawings, and to the letters
of reference marked thereon,

page_text: The object of our Invention is to render more perfect the devices
long in common use for drawing firmly together the parts of doors,
sashes, and other articles of wood in the process of manufacture.
Our improved clamp is composed of two principal parts, viz., a
compound head block exerting pressure on the work by means of a t
screw, and a compound tail block which is capable of being set at
a greater or less distance from the head block; both working in
connection with a long bar which we will designate the clamp stick.
In single-faced joiners' clamps pressure is exerted against the work
at one side of the joint or mortice, and the joint is not closed perfectly
its full length.
In our Invention a pair of self-adjusting shoes or bearing surfaces
bear directly at each side of the mortice, and enclose a joint its full
width in any description of panel or framed work. The arms are
adjustable through the notched plate to various widths at will, and
are also self-adjusting by means of a notched plate partially turning
on a stout pivot, thus allowing the bearing surfaces or shoes a firm
bearing on skewed or slightly bevelled or inclined work. The arms
may admit an adjustment of from 4 to 12 or 14 inches between the
shoes or bearing surfaces. Any square work, the shoulders of which
may have been tenoned or cut out of square (by mismanagement of
machinery or other cause), is brought up and clamped firmly the entire
width of the joint. So also may any work be clamped perfectly when
formed < on a rake," or where the outside stiles of work are narrow
and liable to twist or bulge, thus tending to open a portion of a
joint.
We will proceed to describe what we consider the best means of
carrying out the Invention.
Figure 1 is a longitudinal section; Figure 2, a plan view; Figure 3,
a side view of main casting of the tail block without the plate or arms;
Figure 4, cross section of Figure 3 with the addition of the clamp stick;
Figure 5, a cross section of the head block with its clamp screw and
attachments. Similar letters of reference indicate like parts in all the
Figures.
Λ
alamn stink. D hand an
110

page_text: E, rocking bearing plate; e, spring; F, main casting of tail block;
G, locking pin and holding device.
The Drawing represents the novel parts with so much of the clamp
stick as is necessary to show their relation thereto.
The cap casting B is of the form shown, and held to the stick A
by screws a, and locked thereto by means of the cross ridge B¹ which
is let into a corresponding recess formed in the wood and defends the
entire head block against any end movement. The screw C has a
suitable bearing in the front of the casting B, the upper face of
which is slotted as shown. The screw C being turned by means of
the handle C¹ imparts a backward or forward motion to the rocking
plate E and its attachments. This screw is preferably left-handed,
the inside collar here shown as made separate may be forged on the
screw, and the forms and arrangement of the operating handle may
vary, as will be obvious. The travelling nut D is elongated at its
front and may be braced, as dotted in Figure 1. From the elongated
portion there is an upward extension or stud d of sufficient size to
fill the slot B in the casting B, thus steadying the parts; said stud
being pierced by the large headed bolt m, the head of which is larger
than the width of the slot, and by the lower end of said bolt being
slightly riveted to the nut D, as shewn, serves to hold up and guide
the nut and screw with the entire parts depending thereon. The
plate E rocks on the centre pin or stud d of the nut D, and allows
the arms I, I, to adjust themselves to bear fairly on slightly irregular
or untrue surfaces. This self-adjusting motion of the plate E and
arms I, I, provides what I term an independent yet concerted
backward and forward movement of the arms, and consequently of
the bearing surfaces or shoes J, J. The front of the plate E is
formed with teeth or with recesses into which correspondingly shaped
projections i, i, from the arms I, I, engage, as shown. It will be
noticed that this plate E has cast on its upper surface towards its
back end a pin or projection E which stands in the slot in casting B,
and by making which of a proper size the rocking motion of the
plate E may be limited, thus confining the backward and forward
independent movement of the arms I, I, and their shoes J, J, within
convenient limits. It will also be noticed that this plate E has two
slots near its back end, the object of which is to permit the pins ¿¹³, ¹,
extending downward from the back end of the arms I, I, to pass

page_text: through them. The spring e secured to the plate E maintains pressure
on these pins 1, 2, and by this means the projections i, i, on the arms
I, I, are kept engaged in their respective recesses in the front of
plate E. The slots at the back end of plate E are of sufficient length
to permit the arms I, I, to be moved against the force of the spring e,
or lifted out of any given recesses and dropped into others.
There is
also a projection E¹ from the front of plate E extending downward
which bears against the front of nut D, thus relieving the stud d from
much strain and wear. The front of the nut D is rounded to allow the
correspondingly formed projection E¹ to turn smoothly thereon.
The bearing plates or shoes J, J, form important features of our clamp.
They are each a single casting J so shaped that a continual bearing is
had against the curved end of the arms I, I, thus relieving the bolt
which connects them. These plates are shaped so as to take hold of the
work readily, do not compel any unusual lengthening of the stiles of
the work acted upon, and are not in the way of the joiner's hammer in
driving wedges, &c. It will be noticed that these plates will always
present a true face to the work being acted upon, no matter at what
distance apart the arms I, I, are set, or what angle they may assume in
clamping work out of square or on a rake. The tail block F is held to
the stick A by means of the pin G which passes through the wings ƒ, f,
of the tail block, and stands in one of a series of holes bored through
said stick as shown. The pin G and locking means are shown clearly
in section in Figure 3. A secure and strong connection of the working
parts in the tail block to the main casting may be made by a construc-
tion similar to that of the corresponding parts in the head block, or it
may be effected by means of the stout bolt n. The arms I, I, and face
plates J, J, operate with the spring e and plate E the same as in the
head block. The main casting F of the tail block being slotted for the
pin or projection E² from the upper surface of plate E to pass through
and form a stop as explained in describing the head block. The plate E
in the tail block differs from plate E in clamp screw only as to the
thickness of some portions of it shown in section in Figure 1, but its
operations with the arms I, I, is essentially the same. Any desired length
can be given to the clamp stick.
Figures 6 to 12 represent a modification, Figure 6 being a vertical
section, Figure 7 a plan view, and Figure 12 a cross section through the
head block, and the other Figures representing details detached. In this

page_text: construction the arms are permanently pivoted to a rocking plate some-
what corresponding to the plate E in the former style, and which we
will designate by the same letter E on each side of the pivotal stud d,
and are continued beyond. The stud d extends only partially up through
the plate E, but sufficiently to obtain a fair bearing surface. The bolt m
extends up through both and also through a separate top piece E³, as
shown. The arms I, I, are adjusted apart or together by acting on these
extended back ends which are connected by toggle links x to a pin X,
which may be shifted into either of several holes x¹ in the plate E. In
Figure 7 the arms of the head block are adjusted open or wide apart,
and the arms in the tail block are adjusted closer together. The lower
toggle link has a small piece of wire inserted through its end which
engages with a small slot cut in the pin X, the said slot not extending
to the end of said pin X. By this means the pin X is prevented from
being ever wholly withdrawn from the lower toggle bar, thus preventing
their separation and avoiding much inconvenience, while the said pin
can be easily drawn out sufficiently to clear the pin from the plate E to
allow it to be changed to another hole. There are stops i on the under
face of the arms I which act against the plate E to relieve the pins H
from a great portion of the strain. These stops i also serve to relieve
the strain in another manner. When the arms I, I, are separated to
their widest limit their back ends strike together and brace each other,
and the stops i strike against small stops or shoulders e formed in the
front edge of the plate E. Adequate means are provided for restraining
the swivelling motion of the plate E on both the head block and tail
block. In the head block the plate is made thicker and deeper along
the central line, as indicated by a dotted line in Figure 9, and this is
received in a channel of a little greater width formed in the top of the
nut, or there may be simply projections on the nut cach side if preferred.
In the tail block the front of the main piece or cap casting F has a
hanging lip or projection F¹, which is received in a wider jaw formed in
the front edge of the rocking plate E. On the head block the main
casting is necessarily slotted to allow for the backward and forward
traverse of the stud d. The tail block is correspondingly slotted, but to
a less extent. These slots allow all the changes of position required for
the respective pins X.

page_text: the screw C may be applied to all the modifications described above and
also to those to be described below. So also may the arrangement shown
in Figure 14, in which the clamp screw C is mounted above the surface
of the clamp stick. The arrangement of the arms I, I, and all the parts
in Figure 13 is the same as in Figure 6, except that in Figure 13 the
screw and its operating handle traverse, the screw being threaded through
the main casting and collared in the part corresponding to the nut in
the previous Figure. The main casting B on the head block is secured
in Figure 6, and in the several succeeding modifications not only by the
screws a and by the hanging lip which locks in a recess in the upper
face of the clamp stick, but also by internal lips 61 and 62 at each side.
Figures 15 and 16 show another modification in which the plate E
capable of rocking sufficiently to allow the arms to be shifted into
different notches. The arm I' is bent at the back end to form a segment
of a circle, and the inner face or edge of the segment is recessed or
toothed as shown. The back end of the opposite ari 12 matches into
either of these several recesses as desired. A spiral spring e extending
diagonally between the arms serves to keep the arms engaged in any
position in which they may be adjusted.
Figures 17 and 18 represent a part of another modification in which
the segment fast on the back of one arm is replaced by a link pivoted
permanently to one arm, and having a series of holes by either of which
it may be pivoted to the other by a changeable pin. This pin is locked
by a wire extending into a groove in it, as above described, for the
several other pins to prevent their being entirely removed and lost.
This modification, as shown in Figure 17, is only applied to the tail
block. The same may be applied to the head block, and the screw may
be either above or below the arms, but it is important that the arms
and cross link be above the surface of the main casting B.
Figure 19 is a plan view showing a head block with another modifi-
cation of the means for adjusting the arms. In this a spring e fixed on
the front of the swivelling plate E tends to urge the arms always apart
at their front or working ends. Two pawls are provided near the back
ends, which may be successively brought into play to act against stops
or pins. More than two pawls may be employed if desired, and cach
may have two or more notches to receive the pins. The distance of the
arms I, I, apart may be by these means conveniently and rapidly
graduated

page_text: Figure 20 is a vertical section, and Figure 21 a plan view of another
modification which involves a combination of some of the features in
the preceding. The back of the arm I' is bent inward, and provided
with several pins or stops, while the end of the arm I' is equipped with.
a stout pawl I³ formed with a series of notches 23. This pawl is engaged
with either of the pins ³, which are fixed in the arm I¹ as desired, and
is held engaged by the force of a spring e abutting against a pin or stop
on the arm I², as shown in dotted lines, Figure 21. A slot is cut along
the back of the pawl I³ near its edge to allow the said pawl to work
with the pin or operating knob K. This pin K has no side movement.
Hence to bring the arms I', I², together or to separate them after over-
coming the tension of the spring e, and releasing the hold of the
pawl I³ on either pin , it is necessary to have the said slot in pawl I³.
The narrow part of the slot in the cap casting B is made long to permit
the necessary travel of this pin K. The casting E³ and bolt m hold the
working parts similarly to corresponding parts in Figure 6. The main
casting F of the tail block is formed with a slot of sufficient length to
admit of releasing the pawl I³ attached to arm I'.
Figure 22 is a section, and Figure 23 a plan view showing the head
and connections of another and the last modification which we will
describe. The arms are slotted, and take hold of the pivotal stud d by
means of these slots without the interposition of any plate E. The
arms are continued behind the stud d, and their back ends are strongly
coupled together. The slots are notched with semi-cylindrical notches
adapted to match around the stud d. There may be a spring to urge
the arms I, I, apart, and ensure their remaining engaged with the
stud d if preferred. To adjust the arms they are simply drawn together
until the stud d is out of the notches, then moved backward or forward,
and again spread apart to cause two opposite notches to engage. The
pivot at the back end of the arms may extend up in the slot in the
main casting B, and serve to prevent a too great turning motion on the
stud d.
This head block last described may be used with the tail block
similarly constructed and adjusted, or with a tail block of any of the
other several constructions. So also any of the several modifications
described may be used with different modifications for the opposite
block. There may be many other forms in which the Invention may be
developed. Any and all the arms and bearing shoes should be capable

page_text: not only of being spread apart and contracted together and powerfully
driven forward, but also of swivelling around on the stud d or its
equivalent to allow for inequalities or rake in the material acted
unon.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Henry Goodchild and Samuel Francis
Hay in the Great Seal Patent Office on the 19th September 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, WILLIAM
HENRY GOODCHILD, of Bayonne, Hudson County, State of New Jersey,
United States of America, and SAMUEL FRANCIS HAY, of Brooklyn,
King's County, State of New York, United States of America, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Nineteenth day of March, in the year
of our Lord One thousand eight hundred and seventy-three, in the
thirty-sixth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto us, the said William Henry Goodchild and Samuel
Francis Hay, Her special licence that we, the said William Henry
Goodchild and Samuel Francis Hay, our executors, administrators, and
assigns, or such others as we, the said William Henry Goodchild and
Samuel Francis Hay, our executors, administrators, and assigns, should
at any time agree with, and no others, from time to time and at all
times thereafter during the term therein expressed, should and lawfully
might make, use, exercise, and vend, within the United Kingdom of
Great Britain and Ireland, the Channel Islands, and Isle of Man, an
Invention for "IMPROVEMENTS IN JOINERS' CLAMPS," upon the condition
(amongst others) that we, the said William Henry Goodchild and
Samuel Francis Hay, our executors or administrators, by an instru-
ment in writing under our, or their, or one of their hands and seals,
should particularly describe and ascertain the nature of the said In-
vention, and in what manner the same was to be performed, and
cause the same to be filed in the Great Seal Patent Office within six
calendar months next and immediately after the date of the said Letters
Patent.
19.

page_text: NOW KNOW YE, that we, the said William Henry Goodchild and
Samuel Francis Hay, do hereby declare the nature of our said In-
vention, and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement,
reference being had to the accompanying Drawings forming a part of this
Specification :-
The object of our Invention is to render more perfect the devices long
in common use for drawing firmly together the parts of doors, sashes,
and other articles of wood in the process of manufacture.
Our improved clamp is composed of two principal parts, namely, a
compound head block exerting pressure on the work by means of a
screw, and a compound tail block which is capable of being set at a
greater or less distance from the head block both working in connection
with a long bar which we will designate a clamp stick.
In single faced joiners' clamps pressure is exerted against the work at
one side of the joint or mortise, and the joint is not closed perfectly its
full length.
In our Invention a pair of self adjusting shoes or bearing surfaces
bear directly at each side of the mortise, and enclose a joint its full
width in any description of panel or framed work. The arms are
adjustable through the notched plate to various widths at will, and are
also self-adjusting by means of the notched plate partially turning on a
stout pivot, thus allowing the bearing surfaces or shoes a firm bearing on
skewed or slightly beveled or inclined work. The arms may admit an
adjustment of from four to twelve or fourteen inches between the shoes
or bearing surfaces. Any square work the shoulders of which may
have been tenoned or cut out of square by mismanagement of machinery
or other cause is brought up and clamped firmly the entire width of the
joint. So also may any work be clamped perfectly when formed " on a
rake," or where the outside stiles of work are narrow and liable to twist
or bulge, thus tending to open a portion of the joint.
We will now describe what we consider the best method of carrying
our said Invention into practise.
In the Drawings Figure 1 is a longitudinal section of our Invention
and Figure 2 is a plan of the same; Figure 3 is a side view of main
casting of the tail block without the plate or arms; Figure 4 is a cross

page_text: section of Figure 3 with the addition of the clamp stick; Figure 5 is a
cross section of the head block with its clamp screw and attachments.
Similar letters of reference indicate like parts in all the Figures.
A, clamp stick; B, head or cap casting; C, main screw; D, travelling
nut; C, handle; I, I, arms; J, J, bearing surfaces or shoes; E, rocking
bearing plate; e, spring; F, main casting of tail block; G, locking pin
and holding device.
The Drawing represents the novel parts with so much of the clamp.
stick as is necessary to show their relation thereto.
The cap casting B is of the form shewn and held to the stick A by
screws a, and locked thereto by means of the cross ridge B¹ which is let
into a corresponding recess formed in the wood and defends the entire
head block against any end movement. The screw C has a suitable
bearing in the front of the casting B, the upper face of which is slotted
as shown. The screw C being turned by means of the handle C¹ imparts
a backward or forward motion to the rocking plate E and its attach-
ments. This screw is preferably left-handed. The inside collar here
shewn as made separate may be forged on the screw, and the forms and
arrangement of the operating handle may vary, as will be obvious. The
travelling nut D is elongated at its front, and may be braced as dotted in
Figure 1. From the elongated portion there is an upward extension or
stud d of sufficient size to fill the slot in the casting B, thus steadying
the parts; said stud is pierced by the large headed bolt m, the head of
which is larger than the width of the slot, and by the lower end of said
bolt being slightly rivetted to the nut D, as shown, it serves to hold up
and guide the nut and screw with the entire parts depending thercon.
The plate E rocks on the centre pin or stud d of the nut D, and allows
the arms I, I, to adjust themselves to bear fairly on slightly irregular or
untrue surfaces. This self-adjusting motion of the plate E and arms I, I,
provides what we term an independent yet concerted backward and
forward movement of the arms, and consequently of the bearing surfaces
or shoes J, J. The front of the plate E is formed with teeth or with
recesses into which correspondingly shaped projections i, i, from the
arms I, I, engage as shewn. It will be noticed that this plate E has
cast on its upper surface towards its back end a pin or projection E³
which stands in the slot in casting B, and by making which of a proper
size the rocking motion of the plate E may be limited, thus confining
the backward and forward independent movement of the arms I, I, and

page_text: their shoes J, J, within convenient limits. It will also be noticed that
this plate E has two slots near its back end, the object of which is to
permit the pins ", ", extending downward from the back end of the
arms I, I, to pass through them. The spring secured to the plate E
maintains pressure on these pins, , and by this means the pro-
jections i, i, on the arms I, I, are kept engaged in their respective
recesses in the front of the plate E. The slots at the back end of the
plate E are of sufficient length to permit the arms I, I, to be moved
against the force of the spring e or lifted out of any given recesses and
dropped into others. There is also a projection e¹ from the front of the
plate E extending downward which bears against the front of nut D,
thus relieving the stud d from much strain and wear. The front of the
nut D is rounded to allow the correspondingly formed projection E¹ to
turn smoothly thereon.
The bearing plates or shoes J, J, form important features of our
clamp. They are each a single casting J so shaped that a continual
bearing is had against the curved end of the arms I, I, thus relieving
the bolt which connects them. These plates are shaped so as to take
hold of the work readily, do not compel any unusual lengthening of the
stiles of the work acted upon, and are not in the way of the joiner's
hammer in driving wedges, &c. It will be noticed that these plates
will always present a true face to the work being acted upon, no matter
at what distance apart the arms I, I, are set, or what angle they may
assume in clamping work out of square or on a rake. The tail block F
is held to the stick A by means of the pin G which passes through the
rings of the tail block and stands in one of a series of holes bored
through said stick as shown. The pin G and locking means are shewn
clearly in section in Figure 3. A secure and strong connection of the
working parts in the tail block to the main casting may be made by a
construction similar to that of the corresponding parts in the head block,
or it may be effected by means of the stout bolt n. The arms I, I, and
face plates J, J, operate with the spring e and plate E the same as in
the head block, the main casting F of the tail block being slotted for
the pin or projection E² from the upper surface of plate E to pass
through and form a stop, as explained in describing the head block.
The plate E in the tail block differs from plate E in clamp screw only
as to the thickness of some portions of it shewn in section of Figure 1,
but its operation with the arms I, I, is essentially the same.

page_text: The modification of our clamp, shewn in Figures 6 to 11 inclusive,
permits the adjustment of the arms I both in width between the shoes J
and rocking motion as specified. The rocking plate E, shewn detached
in plan in Figure 9, supports the arms I by means of the bolts i, which
latter form the pivots on which the arms I swing. The toggle bars 7,
shewn detached in side view in Figure 11, are pivotted to the arms I at
their back ends as shewn. Through the bore at their front ends the pin
K passes; this pin is slotted in a manner similar to the large holding pin
G in the tail block in Figures 3 and 4 of the Drawings. The small wire
k passes through the forward end of the lower toggle bar 7 and engages
in the slot in the pin K in such a manner that the latter cannot be
wholly withdrawn from the bars 7, and consequently no difficulty is
experienced by the separation of the toggles while the pin K is being
shifted to any one of the holes e in the plate E, the effect of thus shifting
the pin K is shewn in the extremes of position of the shoes J in Figure
7; Figure 10 shews a part section of the arms I through the bolt i.
The hanging bearing acts against the arched front edge of the plate
E, as shewn in Figure 7, to relieve the bolts i of strain. The notch e¹
at each side of the plates E acts as a bearing for the ends of the bearings
simultaneously with the meeting of the back ends of the arms, as
shewn in the head block in Figure 7. By this means the arms I are
not wrenched when widely separated at the shoes J, and the whole
machine is very materially strengthened. The main screw C, in Figure 6,
is collared at c. The nut D travels backward and forward thereon. The
upward projection d from the elongated front of the nut D acts in a
corresponding recess in the plate E to relieve the connecting bolt d¹ of
strain. The large headed casting F, which is hollowed out to promote
lightness, acts with the bolt & to hold the parts together and prevent
their falling downward from the cap casting B, which is held to the
clamp stick A by means of screws a, and further secured thereto by the
ridges b. On turning the handle C¹ the nut D travels backward and
forward upon the screw C, which is preferably left handed. The arms I
in the head block in Figures 6 and 7 are prevented from rocking too
much by the small stop d², which projects upward from each upper edge
of the nut D by means of the sides of the thick central portion of the
plate E, which strikes at either stop d² in its swinging motion. The tail
block O, in Figures 6 and 7, has substantially the same arrangement of
plate E, arms I, and toggles 7, as the head block. The stout bolt N
holds the part together; and the plate E has a forked projection n from

page_text: its front. The hanging lip n¹ acts to regulate the swing of the plate E
in the tail block by engaging the fork n. The main casting of the tail
block is shewn detached in Figure 8. The holding pin M. is here shewn
with its locking devices M³, which latter are previously described.
Figure 12 is a cross section of Figure 6 through the head block.
In Figure 13 the same arrangement of parts as in the head block for
adjusting the arms I is employed. But instead of the travelling nut D
in Figure 6 the piece H is employed. The cap casting B has a female.
screw cut in its front, through which the main screw C travels backward
and forward as desired.
In Figure 14 the same means are used for the adjustment of the arms
I. The main screw C and all the working parts are mounted above the
cap casting or plate B. The bolt N serves to hold the parts down to the
plate B. It works through the slot in the said plate, and its large end
n being of greater diameter than the width of the slot the parts arc
prevented from rising. The piece D serves to connect the main screw
C to the other parts. This screw C travels in the projecting head nut
B', which is braced as shewn. The head of the pin K is curved to
permit its being drawn out past the screw C, which is directly
over it.
The modification of our self-adjusting clamp, shown in Figures 15 and
16, will now be described. The cap casting B is of the same pattern as
shewn in Figures 6 and 7. The travelling nut D has a stop a, which
acts with the forked projection e from the rocking plate or bar E, to
regulate or limit the backward and forward or rocking movement of the
shoes J. The arms I, I, are pivoted to the bar E as shown. The arm I
is curved at the back as shown. The edge of this curve is indented as
shown. In either of these indents i the heel of the arm I' acts as desired.
The distance between the shoes J is thus determined at the will of the
workman. The overhanging lip e¹ on the main casting of the tail block
G acts with the forked projection e³ to regulate the rocking motion of
the shoes J in the tail block G. This projecting fork e is on the reverse
edge of the plate E to the fork e in the corresponding plate E in the
head block as shewn. The spring F serves to hold the arms engaged in
any position in which they may be placed.
Figure 17 explains a modification in which the adjustment of the
shoes (not shown) is secured by means of pawls M, N, which are pivoted

page_text: on the arm I. The pawl M acts upon pin 1 and 2 upon the arm I¹, and
the pawl N on the pins 2 and 3. The spring I acts to keep either pawl
engaged in any position in which it may be placed. The same regulating
means are employed for the movement of the arms and shoes by a forked
projection and stop, as in Figures 15 and 16. This arrangement of arms
I, I, and pawls M, N, permits the uninterupted travel of the nut D on
the screw C. The said pawls project from the side of the cap casting
B, so as to admit of changing their position easily by the workman.
The arrangement of arms, pauls, and spring can be applied to a tail
block.
The modification shown in Figures 18 and 19 applied to a tail block is
simply a bar C attached to the arm I by a rivit i, and to the arm I' by
the self-locking slotted pin D; any desired distance can be secured
between the shoes (not shown) by changing the position of the pin D
in the bar C. It is necessary in applying this bar and arms to a head
block to place the said bar and arms above the cap casting as the travel
of the parts would not permit the adjustment of the bar C and pin D if
the parts were below.
The modification shewn in Figures 20 and 21 is applied to both head
block and tail block. The arm I is bent and the pins i project upward
therefrom as shown. The arm I¹ is provided with the peculiar shaped
notched pawl K. The spring, which is fastened to the back end of
the pawl K, acts on the small projection ¹ on the arm I' to keep the
notches engaged with cither pin i as desired. The cap casting B is
slotted, as shewn in Figure 21, in order to permit the pin H to travel
with the arms I, I'. This paul K is slotted near its back edge in order to
permit the necessary movement around the pin H while the arms I, I',
are being adjusted. The rocking plates E in both head and tail block,
the means for regulating the movement of the arms by forked projections
and stops, and the general arrangement of the screw and nut are the
same as previously described.
In the modification in Figures 22 and 23 as clearly shown, the arms
I are pivoted together by a rivet a and provided with segmental slots B°,
which latter are semicircularly indented in their inside edge as shown.
The travelling nut c is arranged so that its bolt part at c is of the same
size as the circle formed by any two opposite indents b. It is evident
that by engaging the various opposite indents and bolt at c and

page_text: tightening the upper nut c¹ the shoes (not shown) will be set any
distance apart that may be desired. In practise it would be desirable to
make the cap casting D longer than that shown, as the adjustment as
above explained will take place as well as the traveling way allowed the
nut C. A tail block can be constructed on this plan, as will be obvious.
It is evident that either of the several constructions of head block herein
shown and described can be used with either of the several constructions
of tail block herein set forth, and also that the arrangement of the screw
as shown in Figures 13 and 14 can be applied to any of the several
constructions of head block excepting that plan shown applied to the
tail block in Figures 18 and 19, as previously stated. Any desired length
can be given to the clamp stick.
Having thus fully described our said Invention, and the manner of
performing the same, we wish it understood that we claim, the within
described compound clamp having adjustable and self-adjusting arms
I, I, with swivelling bearing surfaces or shoes J, J, adapted to act on each
side of a joint or mortise, in combination with compressing means when
the arms and their connections are capable of rocking to allow for
inequalities or rake in the material acted upon substantially as and for
the purpose described.
In witness whereof, we, the said William Henry Goodchild and
Samuel Francis Hay, have hereunto set our hands and seals, this
Third day of July, in the year of our Lord One thousand eight
15
Witnesses,
WILLIAM HENRY GOODCHILD. (L.S.)
SAMUEL FRANCIS HAY.
(L.S.)
THOMAS WELLS CAPEN.
WILLIAM GEORG. ABEL.