Improvements in Beam Compasses.
Year: 1896

page_text: Date of Application, 4th Mar., 1896
Complete Specification Left, 3rd Dec., 1896-Accepted. 9th Jan. 1897
upasses.
ALFRED WILLIAM BEVIS, 30 Wellington Road Harborne Birmingham.
Engineer do hereby declare the nature of this invention to be as follows:-
This cumpass mainly consists of two parts, a beam, & a moveable piece, called
a "carrier" to slide along the beam & to carry either the centre or the circumscribing
leg of the cumpass.
The beam may either be straight or curved & may be made of any suitable
material or section. At one or both ends of the beam provision is made to firmly
hold either of the legs of the cumpass which can be fixed into position by a spring
or a screw. The beam may be graduated & marked so as to set the carrier at the
correct distance for describing circles of any size without the aid of an additional
rule; it may also be marked with a scale of chords or of diameters of circles of
given areas.
The carrier is provided with a spring to grip the beam so as to hold it fast &
prevent it slipping while describing circles. By a slight pressure applied while
holding the carrier the tension of the spring against the beam is released & the
carrier can be easily slid along the beam, in order to make any required
adjustment.
To provide that the points of the two legs shall come close to each other, in
order to be able to describe very small circles, either one or both legs are slightly
inclined to the beam; & that end of the beam to which the leg is fixed may be
slightly curved so that the point of the leg which is fixed to the carrier will, when
slid along the beam near to the opposite leg, he swung round by the curve &
brought close to the other leg so that the two points touch each other.
Dated this 2nd day of March 1896.
ALFRED WILLIAM BEVIS.
Improvements in Beam Compasses.
I ALFRED WILLIAM BEVIS of 30 Wellington Road Harborne Birmingham.
in the County of Warwickshire Engineer and Director of Manual Training to the
Birmingham School Board, do hereby ieclare 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 my invention is to enable both large & very small circles to be
drawn by a compass, the central axis, round which the pencil rotates, remaining
perpendicular while drawing any size circle. Also that the adjustment & mani-
pulation of the compass shall be such, that it can be easily worked with one hand.
For these purposes the compass takes the form of what is usually called a beam
compass.
The beam however is curved & has at one end a pencil or pen fixed to it.

page_text: The trammel or clip which slides along the beam, has fixed to it a point and a
handle having their axes in one & the same straight line. The trammel is pro-
vided with a spring or is in itself a spring which grips on to the top & bottom
edge of the beam. By pressing the clip & the beam between the finger and the
thumb the tension of the grip on the top & bottom of the beam is lessened, the
beam can therefore be easily slid forwards or backwards by a slight side motion of
the thumb.
The curve of the beam is such that in whatever position the trammel be in
relative to the beam, the line joining the point of the central axis, & the pencil
point, shall be at right angles to the central axis, but for very small circles the
pencil shall incline inwards to the central axis, & keep parallel to the central axis,
or nearly so, in all other positions as it is moved along the beam.
Fig. 1 shows one adaptation of my invention to a compass. b is a beam made
of thin sheet steel or any other suitable material. p is the pencil or pen fixed at
one end of the beam by the V shaped recesses pressing on both sides of the pencil
by the spring of the material itself. c is the trammel or clip passing round one
side of the beam and gripping it on the top & bottom edges between the four
lugs . .&. The bow shape of the clip, shown at c in Fig. 2, & the material
itself gives the necessary spring to make it grip on to the beam to prevent it
slipping while being used. H is the handle made by bending round a portion of
the material itself the axis being in a line with the point a.
To adjust the compass, press with the thumb & finger the spring c against the
side of the beam b. shown by the two arrows s. s Fig. 2. The pressure of the
clip c is then released from off the top & bottom edges of the beam b. & the beam
can be easily slid forwards or backwards so as to adjust the pencil point d any
distance from the point "a." The line a. d. always keeping at right angles to the
central axis A. H.
The curve of the beam being greater towards the pencil end, allows the pencil
to quickly incline inwards to meet the point a. see Fig. 3. The curve of the beam
being less at the end further from the pencil, keeps the pencil nearly parallel to
the central axis see Figs. 1 & 4.
Although I have described the application of my invention to a simple design
of compass having as few separate pieces as possible it may be arranged, so as to
fit a needle point on to the clip, or a separate spring fixed so as to grip on to the
beam instead of the spring being in one & the same piece as the clip. The beam
may be stiffened with ribs or graduated so as to adjust to any size of circle.
The pencil or pen may be fixed in any other manner than that shown in the
drawings.
Having now particularly described & ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is.
1st. The application of a curved bean instead of a straight one, for the
beam of a compass; to enable small circles to be drawn by it substantially as
described.
2nd. The means of securing the moveable trammel, to the beam, by a spring
which can be released by a slight pressure of the finger when requiring to make
adjustments, substantially as described.
3rd. The fixing of the pencil pen or other marking point direct on to one end
of the beam, instead of having it on a moveable trammel substantially as
described.
Dated this 2nd day of December 1896
ALFRED WILLIAM BEVIS,
Applicant.