A New Instrument for Exactly Dividing Circles.
Year: 1890

page_text: COMPLETE SPECIFICATION.
A New Instrument for Exactly Dividing Circles.
I, EMIL GOLDSCHMITT, of 77 Richard-Wagner Strasse, of Bayreuth, in the
Kingdom of Bavaria, late Paymaster, 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 improved apparatus for exactly dividing circles is illustrated in figs. 1 to 4 of
the accompanying drawing, in which similar letters refer to similar parts throughout
the different figures.
The apparatus essentially consists in a disc made of some elastic material and slitted
on line a (fig. 1, 2, 3) so as in a manner to form the development of a conical
surface. The disc is provided with two different kinds of concentric scales one of
which properly serving for dividing circles is composed of three rows of graduations
and arranged near the circumference of the disc while the second scale shewing how
to employ the former one and containing four rows of numbers, is placed near the
centre.
"
In the following explanation I wish it to be understood that by “dividing
scale" I mean the scale near the periphery and by "employing scale
that nonr
the centre.
The first, second and third rows of the dividing scale counted from the periphery
to the centre are respectively divided into 100, 75 and 60 graduations, each
graduation being provided with the corresponding number. Around the centre of
the disc there is cut a concentric opening a adapted for allowing the disc to be put
over a stand (Fig. 4).
Un employing the apparatns the two edges of the slitted disc are moved one about
the other as far as necessary and hold in their respective position by introducing pins
through the corresponding small holes, which are arranged about the dividing scale
from to the left and to the right to respectively. Another means for the
same purpose and also shown in Fig. 1, consists in guiding slit c d along which a
binding screw e is adapted to move. When the radial edges of the disc aro moved
one about the other the centre of the disc will be elevated and the disc itself then
form a cone. At the same time the dividing scale as well as the opening a¹ become
smaller and smaller in such a manner that on putting b firstly on graduation 100 and
then on graduation 76 (f) of the first row of the dividing scale, the positions shown
in Figs. 3 & 2 will be assumed respectively.
These positions are also represented in Fig. 4 by dotted lines, line A corresponding
to the first position and line B to the end-position. Stand i must be shaped in such
a manner, that it is everywhere exactly surrounded by opening a' when the periphery
of the disc touches the paper. The base plate of stand i has a hollow shape and is
provided with a short pin for exactly fixing the apparatus concentrically around the
centre of the circle to be divided.
In order to make the manner how to employ my dividing instrument more clear, I
relate to the following instance:
A circle is to be divided into 21 parts:
On looking for number 21 in that row of the employing scale as is nearest placed
to the centre we will find number 84 answering to this division and this number 84
placed in the most exterior row corresponding to the first row of the dividing scale.
We therefore move the radial edges of the disc one about the other as far as bis
placed on graduation 84 of the first row of the dividing scale then fixing this position
by means of binding screw e. Now we place stand exactly on the centre of the
circle to be divided and put the disc about the stand so that the periphery of the
disc touches the paper. In the same square containing the number 84 we have
found the little cipher 4 representing the quotient of 84 and 21. We therefore mark

page_text: out on the paper the graduations 4, 8, 12 unto 84 and shall thus get 21 points. By
connecting these points with the centre of the circle to be divided we shall exactly
perform the requirell division into 21 parts.
The second row of the dividing scale is employed for divisions by 34, 35, 36 & 37
as well as by the numbers 61-75, as will be found in the employing scale. The
division point must be transferred from the second row to paper by means of a cord
attached to the stand or hy means of a small rule,
The third row serves for divisions by 26 and by the numbers 51-—GO.
Divisions by 26, 34 and 36 may also be found by means of the first row in such a
manner, that the dividing lines corresponding to the divisions by 13, 17 and 18
respectively are produced beyond the centre of the circle to be divided.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what 1
claim is:
A new instrument for exactly dividing circles consisting in a disc of some elastic
material slitted on line a-b and having concentrical rows divide 1 into graduations of
different number, for the purpose as described.
EMIL GOLDSCHMI FT.
By Rayner & Cassell,
37, Chancery Lane, London, W., Agents for the Applicant.