An Instrument for use in Reproducing Drawings or Designs and the like.
Year: 1891

page_text: Date of Application, 16th Oct., 1891
Complete Specification Left, 15th July, 1892-Accepted. 1st Oct., 1892
PROVISIONAL SPECIFICATION.
An Instrument for use in Reproducing Drawings or Designs and
the like.
I JOSEPH STUBBS STUBBS, of Saint Thomas' Vicarage, Wells in the County of
Somerset, Clerk in Holy Orders do hereby declare the nature of this invention to
be as follows:-
This invention relates to an instrument for use in reproducing drawings and the
like on any required scale.
The principle of the instrument is in part based on the proposition that if a straight
line be drawn parallel to one of the sides of any triangle it will cut the other sides
proportionally, and it is embodied in the form of two arms representing the two sides
of the triangle to be cut, jointed together at the vertex and capable of being fixed
so as to enclose any angle, and of a sliding member in the form of a set square
sliding against one of the said arms, its working edge, which represents, or is
parallel to, the imaginary third side of the triangle, being at any desired angle to
the other two sides the said angle, and likewise the angle enclosed by the sides of
the triangle, being dependent on the desired scale of reproduction, but being constant
in working to any given scale.
The two arms are pivoted about a fixed centre coincident with the vertex of the
enclosed angle and are moved together as one about this centre in plotting down the
points of the drawing to be reproduced, this operation being performed, in con-
junction with the movable set square, in the following manner: The one arm and
the set square being so placed that the point of intersection of their working edges
coincides with a point of the drawing to be plotted, a mark is made at the point of
intersection of the working edges of the set square and of the other arm, which
represents, on the drawing to be made, the point corresponding to that taken on the
original, all the points of the drawing being successively plotted down in this way.
The two arms being moved together as one about a centre so that the enclosed
angle is constant, it will be obvious that as the radial distances from such centre of
the points plotted down are proportional to those of the corresponding points on the
original, the distances apart of any two points in the one will be proportional to the
distances apart of the corresponding points in the other and, therefore, that
the reproduction will be in all respects proportional to the original.
Deted this 16th day of October 1891.
By A. M. & Wm. Clark,
DDD,
53, Chancery Lane, London, Chartered Patent Agents.
COMPLETE SPECIFICATION.
An Instrument for use in Reproducing Drawings or Designs and
the like.
I JOSEPH STUBBS STUBBS of Saint Thomas' Vicarage, Wells, in the County of
Somerset, Clerk in Holy Orders, 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:-
This invention relates to an instrument in the nature of a pantograph for use in
reproducing the outlines of drawings and other figures on any required scale. The
principle of operation of the instrument is based in part on the fact that if a straight

page_text: line be drawn parallel to the base of any triangle it will cut the sides proportionally
and this principle is embodied in the form of a two armed frame (corresponding to
the two sides of the triangle) pivoted about a centre at the vertex and combined
with a sliding member guided by and lying across the arms of the frame at angles
dependent on the scale of reproduction. The slides of this sliding member carry
the one a pointer for following the outlines to be copied and the other a tracer for
reproducing these outlines on a different scale, the position of the one .slide
relatively to the other being so controlled by the connecting member that the radial
distances of the pointer and tracer from the pivotal centre of the frame shall be
always proportional and the distances through which the two points are moved by
the motion of the frame about its centre being proportional to their radial distances
from such centre, it follows that the reproduction will be in all respects proportional
to the original. The scale of this proportion may be varied by varying the angles
which the sliding member makes with the arms of the frame, such variation being
effected by an adjustment of the former with regard to the latter or by altering the.
angle enclosed by the arms, or by both means combined. Instead of the instrument
working pantographically it will be obvious that by omitting the tracer and pointer
it may be used as a guide for the pencil in plotting down the salient features of the
figure to be copied.
Reference is to be had to the accompanying drawings, forming part of this
Specification, wherein
Figure 1 is a plan of the instrument complete for pantographic delineation.
Figures and 3 are respectively detail cross-sections on lines 2-2, 3-3, and
drawn to a larger scale.
Figure 4 shows the most simple form of the instrument.
Referring to Figure 1, the dotted lines ab represent the two sides of a triangle
and the line e represents a line drawn parallel to an imaginary base and which may
make any angle with the sides a b. A B are the two arms of the frame rigidly
braced so as to turn together as one about a fixed centre at C said arms being
furnished with guide rails a' respectively parallel to the lines ab and upon which
slide shoes de which clip the rails a' . To the shoe dis pivoted at d¹ the bar D,
the pivotal centre coinciding with the tracing pin which projects vertically down-
wards in position to be made to follow the outlines to be copied. The bar D lies
across the bars A B and the angles which it makes therewith are regulated by
means of the binding screw f working in a slot in the shoe d concentric to the
pivotal centre d'. This bar D slides through a socket E which lies over and is
pivoted at e upon the shoe e as shown in Figure 3 and in the shoe e is mounted a
vertical spring pressed pencil y in position to mark upon the paper on which the
instrument is placed, said pencil being mounted in that one of a row of holes which
coincides with the point of intersection of the line with the centre line c of the
bar D. By sliding the shoe d along the bar A and so moving the bar D up or
down and at same time moving the whole frame A B about its centre C so as to
cause the tracer d² to follow the outline of the figure to be reproduced the shoe e
will be caused to slide along the bar B and the socket E along the bar D so that
the pencil g will be caused to describe a figure which is similar and proportional to
the figure followed by the tracer, the ratio depending on the angle at which the
bar D is adjusted. By inverting the positions of the tracer and pencil and of the
original and reproduced figures the ratio of proportion will be reversed. It will be
obvious that the scale of reproduction may-also be varied by making the bars A B
adjustable with regard to each other about the centre C so as to vary the enclosed
angle and consequently the angles which bar D makes with them. Instead therefore
of being a rigid frame, bars A B would in this case be separately pivoted upon their
common centre C and rigidly braced at any required angular distance by any
suitable means, e.g. an adjustable link connecting their extremities.
In this case the bar D may be at a fixed angle to bar A instead of being adjustable
as described. It will also be obvious that instead of the pencil making continuous

page_text: lines, it may be raised off the paper whilst shifting the bar D and pressed down at
each point where it is required to plot down the salient points of the original to be
copied. Or the pencil may be omitted and a pricker inserted through one of the
holes h for the same purpose, allowance being made in setting the bar D for the
distance which the hole selected deviates from the line e if the scale of reproduction
is required to be accurately to a given ratio. Similarly the tracer might be omitted
and the salient points of the original merely sighted through the hole which it
occupies.
с
For simply plotting down, the shoe e and socket E might be dispensed with and
the shoe d replaced by a head similar to that of a common T-square, this head D¹
which may be a shifting one secured by a binding screw simply bearing against the
bar A, (all as shown in Figure 4). In this case the angles of intersection of the
edge of bar D with the edges of bars A and B are a sufficient guide for the eye or
for the plotting instrument, as the case may be, in making the apparatus coincide
with the several points of the original figure, and plotting them down for the
reproduction.
In Figure 4 there is shown an original and reproduction of a simple drawing to a
different scale. To reduce error to a minimum, it is preferable to place the plotting
instrument in an obtuse angle, as at Figure 4 for instance, for enlarging, and as
at y for reducing, as it is immaterial which edge of D is taken as a guide. The
arms A B although moving together as one on the pivot C are adjustable as to their
angular distance by the binding screw and sloth or by an adjustable stay at their
other extremities.
It is however preferred to employ the more perfect form of instrument described
and illustrated as, by its means, either tracing or plotting may be effected.
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.
1. An instrument for use in reproducing drawings and the like, consisting of a
two-armed frame enclosing an angle and movable about a centre at the vertex, in
combination with a bar lying across the frame and guided by the one arm so as to
be movable towards or away from the centre of motion whilst remaining parallel to
itself for use in the manner and for the purpose specified.
2. An instrument for use in reproducing drawings and the like, consisting of a
two-armed frame enclosing an angle and movable about a centre at the vertex, in
combination with a bar lying across the frame, said bar being capable of being set
to work at various angles and guided by the one arm so as to be movable towards
or away from the centre of motion whilst remaining parallel to itself for use in the
manner and for the purpose specified.
3. An instrument for use in reproducing drawings and the like consisting of a
two-armed frame enclosing an angle and movable about a centre at the vertex, in
combination with a bar attached at one end to a shoe sliding on a guide rail on the
one arm and sliding through a socket pivoted upon a shoe sliding on a guide rail on
the other arm, substantially as specified.
4. An instrument for use in reproducing drawings and the like, consisting of a
two-armed frame enclosing an angle and movable about a centre at the vertex, in
combination with a bar attached at one end to a shoe sliding on a guide rail on the
one arm and sliding through a socket pivoted upon a shoe sliding on a guide rail on
the other arm, substantially as specified, a tracing point being mounted in the one
shoe and a pencil in the other so as to respectively follow and reproduce the outlines
of the drawing to be copied, substantially as specified.
5. An instrument for use in reproducing drawings and the like consisting of a
two-armed frame enclosing an angle and movable about a centre at the vertex, the
arms being adjustable with regard to each other so as to vary the enclosed angle, in
combination with a bar lying across the frame and guided by one of the arms so as

page_text: to be movable thereon whilst remaining parallel to itself, substantially in the manner
and for the purpose specified.
Dated this 15th day of July 1892.
By A. M. & Wm. Clark,
UDDD,
53, Chancery Lane, London, Chartered Patent Agents.