An Improvement in Compasses, Dividers, Callipers, and other similar Instruments.
Year: 1894

page_text: Date of Application; 22nd May, 1894
Complete Specification Left, 22nd Feb., 1895-Accepted, 6th Apr.,
1895
PROVISIONAL SPECIFICATION,
An Improvement in Compasses, Dividers, Callipers, and other similar
Instruments.
I, EDMOUND FLOWER, of Harrow Weald, in the County of Middlesex,
Gentleman, do hereby declare the nature of this invention. to be as follows:-
My invention relates to an improvement in the head and knee joints of compasses,
dividers, callipers, and other similar instruments; and it has for its object to impart,
in a permanent and efficient manner, the "dead" stiffness to the joint which is
requisite in such instruments and to provide improved means of fixing a carpenter's
or mechanic's compass, dividers, or callipers, at any width of opening, after taking.
a measurement which requires to be repeatedly used.
The improvement in the head and knee joints consists in making, one or more of
the tenons or knuckles (attached to one of the legs or portions of the leg to be
jointed together) of two thicknesses of metal which have a tendency to spring
apart so as to bear against the adjacent faces of the tenons or knuckles of the
other leg, or portion of a leg, between which they are confined, with the pressure
and consequent friction necessary to produce the desired "dead" stiffness of the
joint:
These spring tenons may either be made of two plates of spring steel, rivetted
by. one end into the leg or part of the leg to which they appertain, the strips being
oppositely curved, so that their projecting portions are slightly, divergent, so that
these divergent portions must be pressed together in order to insert them between
the other tenons forming the joint.
Or, instead of the tenons being. made of separate steel strips, a tenon which is
solid with the brass or other leg is sawn through in its own central plane so as to
divide it into two thicknesses which receive a slight set apart so as give them the
divergence requisite to produce the spring pressure required, the saw-cut extending
sufficiently far down the leg to enable this to be done and to admit of a set-screw
being inserted in a hole tapped in the one of such divided portions and bearing
with its point against the inner face of the other divided portion, so as to forcibly
expand the tenon sufficiently to tighten the joint and so fix the compass at any
measurement which has been taken..
Dated this 2nd day of Mov 1894
CUMILELE
5 An Improvement in Compasses, Dividers, Callipers, and other similar
Instruments.
I, EDMOUND FLOWER, of Harrow Weald, in the County of Middlesex,
Gentleman, do hereby declare the nature of this invention, and in what manner the
same is to be performed to be particularly described and ascertained in and by the
▸ following statement :―
My invention relates to an improvement in the head and knee joints of compasses,

page_text: dividers, callipers and other similar instruments, and it has for its object to impart,
in a permanent and efficient manner, the "dead" stiffness to the joint which is
requisite in such instruments and to provide improved means of fixing a carpenter's
or mechanic's compass, dividers, or callipers, at any width of opening, after taking
a measurement which requires to be repeatedly used.
The improvement in the head and knee joints consists in so making one or more
of the tenons or knuckles forming one member of the joint, that they have a
tendency to diverge and bear against the adjacent faces of the tenons or knuckles
of the other member or portion of the joint or of the disc or nuts between which
they are confined. By means of the spring pressure thus obtained the friction
necessary to produce the desired "dead" stiffness of the joint is ensured.
These spring tenons may either be made of two plates rivetted into and forming
part of the leg or portion of the leg to which they appertain, the plates being
oppositely curved, so that their projecting portions are slightly divergent and must
bé pressed together in order to be inserted between the other tenons forming the
joint.
Or, instead of the tenons being made of separate strips, a tenon which is solid
with the brass or other leg is sawn through in its own central plane so as to divide
it into two thicknesses which receive a slight "set "in opposite directions so as to
cause them to diverge and produce the spring pressure required the saw-cut
extending sufficiently far down the leg to enable this divergence to be obtained and
to admit of a set-screw inserted in a hole tapped in the one of such divided portions
bearing against the inner face of the other divided portion, so as to forcibly expand
the tenor sufficiently to tighten the joint and so fix the compass at any measurement
which has been taken.
Reference is to be had to the accompanying drawings, forming part of this
Specification, wherein
Figure 1 shews'a face view, and Figure 2 an edge'view, of compasses constructed
as first above described.
Figure 3 shews the two parts of a leg detached, the divergence of the tenons
being exaggerated.
Figure 4 is a sectional elevation of a mechanic's compass, and Figure 5 a similar
view of a knee-jointed compass in which the tenons are cast solid with the members
of the legs.
Figure 6 is a face view of callipers, and Figure 7 a section of same, (the joint
rivet being removed), on line 7-7 Figure 6.
Referring to Figures 1, 2, 3, the upper parts or members A, A, of each leg are
constructed of four plates of hard brass or other springy metal a, a, a', a', rivetted
together at a², two of the plates a, a, being formed with circular tenons or
knuckles b, b, the knuckles of the one leg entering between those of the other leg
and, together with the centre pin 6', and discs 63, screwing or rivetted on the ends
of said pin, constituting the head joint, B. The lower members C are jointed to
the upper members A by knee joints D for which purpose the two outermost
members a, a, of each part A are formed with knuckles d projecting beyond the
ends of the two innermost plates, whilst the parts C are each formed of two
plates c, c, rivetted together at c', their upper ends forming tenons or knuckles and
being received between the knuckles d whilst their other ends are suitably adapted
for holding the needle or pencil points, as shewn. The two plates c, c, are oppositely
curved, as shewn to a magnified extent in Figure 3, so that the tenons or knuckles
at their upper ends will diverge and bear against the knuckles d between which
they are rivetted whilst the lower ends which also diverge to receive the needle or
pencil points may be tightened by a set screw or by sliding clips e.
In Figure 4, it will be seen that the one leg of the instrument is cast solid and in
one with the tenons which are formed and rendered springy by means of a central
saw-cut f dividing the single tenon cast on the leg into two tenons g, g, which are
set or bent outwards by an instrument inserted between them. is a set screw by

page_text: which the pressure due to the divergence of the tenons g, g, may be so increased as
to fix the compass at any measurement.
Figure 5 shews one leg of a knee-jointed compass of which the head and knee
joints are made as described in reference to Figure 4.
In both cases, the other leg of the instrument, not shewn in Figures 4 and 5, has
the tenons cast with it, but has no saw-cut, and the centre pins of the joints are
either screwed or rivetted to the discs i.
The callipers shewn in Figures 6 and 7 have a spring tenon or knuckle, rivetted
at to the one leg and confined by the head of the joint pin rivet k, said tenon
being tapped to receive the set screw whereby the pressure of the tenon against
the head of the joint pin rivet is regulated.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
--
1. The construction, substantially as and for the purpose specified, of the head
and knee joints of compasses and similar instruments with spring tenons or knuckles
formed on plates rivetted to the members of the leg, the tenons or knuckles of one
member being bent apart so as to bear against the adjacent faces of the tenons or
knuckles of the other member or of the heads of the joint pin, as described.
2. The construction, substantially as and for the purpose specified, of the head
and knee joints of compasses and similar instruments with spring tenons or
knuckles cast in one with the members of the leg and split by a saw-cut, as
described.
3. The combination, with the head joint of compasses, callipers, or like
instruments, having spring tenons or knuckles cast in one with the leg and divided
by a saw-cut or rivetted to the leg, as described, of a set-screw for making the joint
fast, as specified.
Dated thi
1005
A. M. & WM. CLARK,
53, Chancery Lane, London, Chartered Patent Agents.