Improved Appliance for Drawing Straight Lines at Right Angles or Parallel to the Radii of a Circle, or at other Specified Angles.
Year: 1894

page_text: Date of Application, 4th Apr., 1894-Accepted, 21st July, 1894
COMPLETE SPECIFICATION.
Improved Appliance for Drawing Straight Lines at Right Angles or
Parallel to the Radii of a Circle, or at other Specified Angles.
BERNARD KAHL, Civil Engineer, EBERHARD SCHUMACHER, Mechanic, and
CARL ROCHOLL, Mechanic, all at 36, Salisbury Road, Highgate Hill, London, N.
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 :-
The object of this invention is to facilitate drawing firstly straight lines at
90 degrees to radii in any direction and at any distance to the centre of a circle
without measuring with a compass, as well as straight lines at any other angle to a
radius; especially to obviate that disagreeable and time absorbing setting of
T squares, chiefly when these lines have to be continually repeated or when each
line has to be drawn to a different radius; secondly to draw straight lines parallel
at any distance to radii in any direction with the same facility and instantly.
Fig. 1 on the accompanying drawing represents the instrument for drawing
straight lines at right angles or others, and
Fig. 2 that for drawing straight lines parallel to radii of a circle;
Fig. 3 is a front view of B and A up to the section line xx and
Fig. 4 a front view of D and E up to the section line z z.
O represents on all figures a point, which, like the point of a compass, has to be
put into the centre of circle of a drawing; the bevelled edges of the part A,
Fig. 1, being at right angles with the length-axis of the graduated part B; A on
each bevelled edge bears a mark C; if C is put just on the radius, the bevelled
edge of A will be found to be at an angle of 90 degrees to the radius; in that
manner it will be easy to draw straight lines at right angles to any radius in any
position; if lines have to be repeated one has only to keep in memory the
measurement, which is to be read by a vernier on the sliding part of A; to draw
lines at any other specified angles to radii one has only to move the instrument
round O, like a compass being moved round one of its points, while with its other
point a circle or a part of a circle being described, until it arrives at the proper
angle; if such lines have to be repeated or transfered to other radii one has only
to put the same division-mark of the inner edge of A on the radius and in this
position of the instrument to draw the line, which will be at the same angle to the
radius as the preceding.
On Fig. 2 O is found to be on the same line with the inner bevelled edge of D ;
that edge has to be put coincident with the radius; the sliding part E being with
both its bevelled edges parallel with the inner edge of D, allows the operator to
draw straight lines parallel to any radius in any position and at any distance to the
same, without measuring with a compass, by putting, as in the case of Fig. 1, the
vernier at the given measure.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed we declare that what we
claim is :-
The instruments above described for drawing straight lines at right angles,
parallel or at other specified angles to radii of a circle and characterized by the
following novel features:-
First. The graduated part B sliding at right angles to and in an arm of A, by
means of which the lines are drawn.

page_text: straight lines at given distances from a centre by reading any measurement on a
vernier and by the means of which all measuring with compasses or otherwise are
rendered unnecessary and therefore the time is saved.
Third. The device for sliding the two rule-arms of the instrument, shewn
in Fig. 2, parallel to each other by means of the graduated part which forms a
right angle with D and by means of which, in combination with a vernier on E
any given measurements can be read as in the case of the instrument shewn
in Fig. 1, and straight lines can be drawn parallel to each other.
Fourth. The points O in combination with the instrument as set forth.
BERNARD KAHL.
E. SCHUMACHER.
CARL ROCHOLL.