-off or plotting geometric or other figures
Year: 1886

page_text: Date of Application, 29th Dec., 1886.
Specification Accepted, 1st Feb., 1887
Pennsylvania, United States of America, 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 improved device for laying-off or plotting geometric or
other figures.
The improved device embodying this invention consists of a disc having triangular
and other figures, the inner circumference of the rim being formed of right lines and
segments, and scrolls and other features provided whereby various geometric figures
may be laid off.
The accompanying drawing shows a. face view of the said device.
A represents a disc having a rim A¹, suitably graduated and adapted to be used as
a protractor. Within the disc is a series of openings bounded by right lines and
segments of different dimensions for laying off polygonal figures, sectors, chords,
segments, or other figures. The disc is divided by a portion of these openings into
figures B and C, from which a triangle, or other figure may be drawn. The cross bar
or figure I) is also formed by the outlines of a portion of the openings.
These several parts are connected to each other and to the rim, as is seen in the
drawing. The base of the figure B joins the cross bar D, and between the said figure
and cross bar is a line of perforations E, which line forms a continuation of the side
or edge F of the bar D, and with it constitutes the diameter of a circle, the centre
of which is perforated at G to receive a pin on which the disc may be rotated.
In the cross bar Dare perforations H and swelled scrolls H¹, which extend from
near the centre of the disc outwardly toward the circumference, and in the figure B is
the slot J, of somewhat elliptical form. In the figure B are also circular openings J, J
To avoid weakening of the bar D the perforations E and H are made on opposite
sides thereof. One line of perforations is adapted to receive the point of a pencil and
the other that of a pin, so that by rotating the disc circles of different diameters may
be drawn. The circles may be drawn from the centre G, the pencil point being
inserted in either of the perforations E, H or at the corners of the figures B, C, or
scrolls H.

page_text: It will be seen than when the disce is placed on a piece of paper, a slate or the like,
on which it is desired to draw gocmetric figures, such figures may be drawn by
guiding the pencil along the sides of the several parts as formed, and then turning the
disc and marking off another section or part of a figure, and so on continuously to the
end. Thus the base of the triangle formed by the figure C is the side of a square:
hence, after one side is drawn the other sides may be formed by turning the disc the
requisite number of times, each time marking another side.
The side of the bar D may be used for forming a triangle, and also the chord of
an arc. The hypotenuse of the right angled triangle formed by the figure B may be
used to draw a pentagon. The right lines of the rim A are employed for polygons,
those shown being for six, eight, ten, and twelve sides. Segments, sectors, chords,
circles, scrolls, etc., may be described and drawn by using the proper part of the
figures, etc. approximately. Elliptical shaped figures may be described and marked
off by using the scrolls H, and slot J, proper judgment in all cases being exercised to
rotate the disc to the required extent in order to produce correctness in the resultant
figures. Where the lines of the figures do not meet or extend the full length, they
may be readily continued. The line F of the bar D and the line of perforations E are
employed as the diameter of the circle formed by the disc, and a radius may be
described, using either the said line F, either of the perforations E, or the per-
pendicular d of the right-angled triangle formed by the figure B.
The instrument will be found especially useful for children for purposes of plotting
and drawing geometric and fanciful figures without necessarily employing dividers
and rulers, especially as any other regular or irregular devices may be inserted
within the rim to produce corresponding figures.
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 :-
First. A plotter consisting of a disc having openings therein, the sides of which are
bounded by right lines of different lengths, forming sides of regular polygons whose
centres are coincident with the centre of the disc, and portions of a circle concentric
with the circumference of the disc, also having perforations extending radially, scrolls,
and circular openings, substantially as described.
Second. A disc having openings forming the outlines of figures B, C, and D, of the
shape substantially as described, the figure B having the slot J, and the figure D
having the swelled scrolls H', as stated.
Third. A disc having a graduated rim, and having openings, substantially as
described, forming figures B, C and D, the said figures B and D each having a series
of perforations, and the figure B having circular openings J', substantially as
described.
Fourth. The disc A having openings forming figures B, C and D, the figure D
having scroll shaped openings H, and the figure B having opening J, and circular
openings J, substantially as described.
HASELTINE, LAKE & CO.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicants.