IMPROVEMENTS IN MATHEMATICAL COMPASSES AND SIMILAR INSTRUMENTS
Year: 1884

page_text: We JAMES FREDERICK BENNETT, Engraver of 41 Cemetery Road, Sheffield.
and BENJAMIN BATTY SMITH, Joiners Tool Manufacturer of 204 Gleadless
Road Sheffield in the County of York, do hereby declare the nature of our
said invention for IMPROVEMENTS IN MATHEMATICAL COMPASSES AND SIMILAR
INSTRUMENTS to be as follows:-
Our invention relates to improvements in the construction of mathematical
compasses and other similar instruments, by which term we mean instruments
constructed to perform the same work as compasses but which, strictly speaking,
might not be included in the term " "compasses."
The object of the invention is to construct an instrument or instruments by
means of which a great variety of figures may be drawn, or set out, such as circles,
ovals, spirals, elipses, and other regular or irregular forms, and we accomplish this
object by constructing the instrument with. a fixed or non-rotating foot or leg, in
combination with various mechanical details hereinafter described.
Our invention consists chiefly in the use of a foot or leg, that during the use of
the instrument is fixed or non-rotating, in combination with a moveable leg that can
be revolved round the fixed or non-rotating foot or leg, in conjunction with various
mechanical devices, according to the figures required, the action in all cases except
in the forming of circles, being dependent upon the fixed or non-rotating foot
or leg.
In carrying out our invention, we prefer to make the fixed foot or leg with more
than one point the centre point being the longest; these points when pressed into
the paper prevent the foot or leg rotating.
At a suitable height from the foot a joint is formed, which enables the other leg
to be turned round, and to adjust itself to its work-The legs are kept apart by a
suitable spring.
To enable this instrument to describe an elipse, we fix a crossbar upon the
stationary leg, with a small pulley at each end, round which a slack loop of cord,
chain or other material is placed and which is also attached to the other leg, in
such a manner that the size of the loop can be altered.-When the loose leg of the
instrument is made to revolve, the pencil or pin will describe an elipse.

page_text: If a fixed cone is substituted for a crossbar and a string, cord or chain is
attached both to it and to the revolving leg, the compass or being revolved will
describe a volute or spiral figure.
To construct an instrument that is capable of producing in varying dimensions,
any kind of regular or irregular figure, from a templet, we make the loose leg to
be drawn towards the other by means of a spring, and upon the non-rotating leg,
we fix a templet or model of the desired figure, such as for instance a hexagon cut
from sheet brass, for nuts in mechanical work.
Upon the loose leg we fix an adjustable alide having a small pulley or pointer, sO
fixed that it will travel round the edge or perimeter of the templet, that is upon
the other leg. If a second slide be used to carry the pen or pencil, and is fitted to
the bottom of the loose leg, the shape of the figure may be varied considerably.
A modification of the last described instrument is made by the legs being made
parallel, the loose leg being held by a cross slide which may revolve round the
fixed leg and is drawn towards the non-rotating leg by means of a spring or
springs. Similar attachments to those before described may be used with this
instrument.

page_text: COMPLETE SPECIFICATION.
We JAMES FREDERICK BENNETT, of 41 Cemetery Road Sheffield, Engraver, and
BENJAMIN BATTY SMITH of 204 Gleadless Road, Sheffield in the County of York,
Joiners Tool Manufacturer, do hereby declare the nature of our invention for
IMPROVEMENTS IN MATHEMATICAL COMPASSES AND SIMILAR INSTRUMENTS, and in
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement, that is to say :-
Our invention relates to improvements in the construction of mathematical
Compasses and other similar instruments, by which term we mean "instruments
constructed to perform the same or similar work as Compasses" but which strictly
speaking might not be included in the term "Compasses."
The object of our invention is to construct an instrument or instruments by
means of which a great variety of figures may be drawn or set out, such as circles,
ovals, spirals, ellipses, and other regular or irregular forms, and we accomplish this
object by constructing the said instrument with a fixed or non-rotating foot and
leg in combination with various mechanical details hereinafter described.
Our invention consists in the adaptation to compasses and similar instruments
of a nonrotating foot and leg, to which various mechanical devices, and templets,
may be attached, for accomplishing the purposes herein before specified.
And in order that our invention may be fully understood, we have annexed a
sheet of drawings, illustrating two forms of instruments made according to our
invention, in which the same letters of reference indicate the same or similar parts
in either of the figures.
Fig. 1, represents an instrument or compass which may be used for describing
circles, ellipses and other figures.
Fig. 2, represents an instrument which may be used to describe circles spirals or
volutes.
In carrying out our invention in the construction of the instrument shown in
Fig. 1, we make the non-rotating leg A, with a moveable foot B, to which it is
attached by means of a ball joint C, which however has not the usual universal
movement of such joints, the horizontal rotary motion being prevented by two
pins passed through the sides of the foot B, and entering a groove formed on the
periphery of the ball C, and which is represented by a black line in the drawing.
Upon the leg A, is fitted an adjustable slide E, to which a templet F. of
any desired shape may be secured by the collar G-these parts are shown
separately and marked E, F and G. The non-rotating leg is attached to the
other parts of the instrument by a joint at H, the separate parts being shown and
marked K and A¹.
Between the two legs of the instrument we fix a guide bar J, to which is
attached the quadrant I, a similar quadrant L, being placed lower down the guide
bar, and passing through the leg M, to which it may be secured by means of a
screw.

page_text: This guide bar is held against the edge or perimeter of the templet F, by the
action of a spiral spring N, (or a coiled spring may be placed inside the joint K,
if preferred) thus when the leg is turned round to describe the figure, it reproduces
an enlarged facsimile of the templet F, of any desired size within the capacity of
the instrument, and by adjusting the position of templet and quadrants, variations
of the figure may be obtained.
The foot B, has two or more points to prevent rotation the one in the centre,
being made longer than the others for convenience in using the instrument.
A modification for describing ellipses may be made by fixing a cross bar to the
non-rotating leg A, with a small pulley at each end, round which, and the other
leg, a loop of cord, or its equivalent may be placed, when the loose leg is made to
revolve, the pencil will describe an ellipse.
A similar result may be obtained by making the non-rotating leg of a compass
in three lengths, connected by two knuckle joints, moving at right angles one to
the other, this is a very simple form of instrument.
The instrument shown in, Fig. 2, has, a similar non-rotating leg and foot A
and B, to those described' in Fig. 1, and when required for drawing spirals or volutes,
a spring R, is required to forced the legs apart. Upon the non-rotating leg A, we
fix a cone O, to which is attached one end of a cord or chain P, the other end
being held by an appliance Q, upon the outer leg. It is evident that when the
instrument is rotated, the cord or chain will be wound upon the cone, drawing the
pen or pencil nearer to the centre, and describing a volute or spiral figure.
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed; we declare that what
we claim is
1st In mathematical compasses and other similar instruments for describing
geometrical forms other than circles, the use of a non-rotating foot and leg, for the
purpose specified, and substantially as described and illustrated.
2nd In Mathematical Compasses and other similar instruments for describing"
geometrical forms the use of fixed or adjustable templets attached to a non-rotating
leg, substantially as described and illustrated.
3rd The Mathematical instrument, substantially as hereinbefore described, and
as illustrated in Fig 1. of the drawings.
4th The Mathematical instrument, substantially as hereinbefore described, and as
illustrated in Fig 2. of the drawings.
DOLL 1
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