Improvements in Drawing Compasses.
Year: 1892

page_text: COMPLETE SPECIFICATION.
Improvements in Drawing Compasses.
A communication by MORITZ ULLMANN, of 55, Olgastrasse, Stuttgart, in the
Empire of Germany.
I, WILLIAM PHILLIPS THOMPSON, F.C.S. M.I.M.E. of the Agency for
Foreign Patent Solicitors, 6 Lord Street, Liverpool & 6 Bank Street, Man-
chester, both in the County of Lancaster, and 323 High Holborn in the County of
Middlesex, Civil Engineer, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and ascer--
tained in and by the following statement :--
This invention relates to drawing compasses and has for its object to automatically
hold apart the two members of a pair of compasses by means of a spiral spring
situated in the head of the instrument in such a way that when they are to be
adjusted to a given extent this must be performed by pressing together the
two legs.
When these latter have assumed the requisite position they are retained therein
by means of a stirrup or catch attached to one leg of the compasses and arranged
so as to press against the head of the other, until by applying pressure on the
stirrup, the latter is removed from the head and both legs are again separated
automatically by means of the spiral spring.
In order that the invention may be the more easily understood, reference is made
to the accompanying sheet of drawings, in which these improved compasses are shown
in Figures 1 to 5. Figures 2 and 4 are views of one leg, B, and Figures 3 and 5
of the other leg A, being front and side views respectively of the same. Figure 1 is
a section through the compasses when put together.
The leg A has a hollow head a in which the sleeve 6 of the leg B, which is also
hollow, is inserted, and is connected therewith by means of a screw c attached to a.
Inside the hollow sleeve b a spiral spring s is arranged, attached by one end to the
screw pin c and at the other end to the hollow sleeve b in such a way that the two
legs A and B are separated by means of the force of the spring s.
The stirrup or catch fattached to the leg B presses with its projection against
the outside of the hollow head a of the leg A, for which the angle between the lines
of connection of the centre of c with the point of contact of the stirrup and with the
point of attachment of the same must be smaller than the angle of friction of the
substances used for a and f. Both legs A and B are thereby prevented, by f acting
on the edge of a, from separating, the stirrup becoming fixed, and holding the
compass legs in their existing position. By a slight pressure on the part of the
curved piece f, which projects beyond the leg B, the catch on the former is released,
and the compasses can then be again adjusted. Similar automatic fixing devices
may also be employed in the binges of the adjustable pencil, pen or needle holder
of drawing compasses.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me by
my foreign correspondent, I declare that what I claim is :-
1. The improvement in drawing compasses, which consists in providing them with
a spiral or coiled spring arranged in the hollow head of the instrument, and connected
with the pin (c) and the sleeve (b), and with a stirrup or catch ƒ so arranged that
the legs can be locked in any desired position or released by pressing the catch by
the hand, substantially as described.

page_text: 2. The general construction and arrangement of parts forming the improved
drawing compasses, substantially as described.
Dated this 18th day of June 1800
WM. P. THOMPSON & Co.,
Agents for the Applicant.