A NEW OR IMPROVED APPA- BATUS FOR ENABLING DRAUGHTSMEN AND OTHERS TO DRAW ELLIPTICAL CURVES AND OTHER GEOMETRICAL CURVES AND FIGURES WITH GREATER FACILITY THAN ' HERETOFORE.
Year: 1871

page_text: LETTERS PATENT to Edward Burstow, of Horsham, in the County of
Sussex, Architect, for the Invention of "A NEW OR IMPROVED APPA-
BATUS FOR ENABLING DRAUGHTSMEN AND OTHERS TO DRAW ELLIPTICAL CURVES
AND OTHER GEOMETRICAL CURVES AND FIGURES WITH GREATER FACILITY THAN
'
HERETOFORE.
"
Sealed the 1st August 1871, and dated the 6th February 1871.
PROVISIONAL SPECIFICATION left by the said Edward Burstow at
the Office of the Commissioners of Patents, with his Petition, on
the 6th February 1871.
I, EDWARD BURSTOW, of Horsham, in the County of Sussex, Architect,
do hereby declare the nature of the said Invention for "A NEW OB
IMPROVED APARATUS FOR ENABLING DRAUGHTSMEN AND OTHERS TO DRAW ELLIPTICAL
CURVES AND OTHER GEOMETRICAL CURVES AND FIGURES WITH GREATER FACILITY
THAN HERETOFORE," to be as follows:-
This Invention consists of a mechanical arrangement of parts by
means of which a pen or other instrument is caused to travel in an

page_text: ellipsis or series of elliptical curves and other geometrical curves and
figures, and if required to draw the same.
The apparatus by which I propose to effect these objects consists of
a stand supporting a horizontal frame or bed, from one end of which
rises a fixed arm which terminates over the centre of the instrument in
a head or socket, through which passes a vertical spindle, terminating
above in a milled head or other suitable handle by which motion is given
to the apparatus. The lower part of this spindle carries a horizontal
bar to a slide and clamp, on which is attached a pin or axle, which
travelling in a circle gives motion to a wheel and an arm herein-after
described as arm C. In the bed above mentioned work two slides which
may either work separately or one within the other, as herein-after
described. The principal or largest slide, which is herein-after described
as slide A, is formed of a piece of metal or other suitable material, by
preference about equal in length to the bed, has near its centre a slot or
parallelogram shaped opening, within which works a second slide
herein-after called slide B, through the centre of which passes a vertical
spindle or axle, the lower extremity of which carries a horizontal bar, to
which is attached a pen or other instrument, and the upper extremity
of which terminates in a wheel herein-after described. From or near
one extremity of the slide A rises a vertical pin or axle, on which moves
freely a horizontal arm herein-before described as arm C. This arm is
pierced by two other spindles or pins, one at or near the other or free
extremity, and herein-before described as attached to a slide and clamp,
and carrying a wheel, &c., the other at or about its centre, also carrying
a wheel, and forming a joint on which moves another arm, the other end
of which is attached to and turns on the spindle passing through the
slide B. To each of the three spindles last above mentioned, namely,
that in the slide B, that at the centre of the arm C, and that at the free
end of the arm C is attached to a wheel, and these wheels are connected
together either by cogs, bands, chains, or other suitable contrivance.
The wheel at the free end of the arm C is turned by the spindle or axle
operated upon by the bar connecting it with the milled head or handle
above, and communicates motion to the wheel in the centre of the
arm C, which again communicates motion to the wheel on the centre of
the slide B, thereby giving motion to the pen or other instrument
connected therewith, and thus by the combined action of the arms,

page_text: wheels, and slides, causing the pen or other instrument to travel in an
ellipsis or series of elliptical curves, and other geometrical curves and
figures, and if required to draw the same.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Edward Burstow in the Great Seal Patent Office
on the 3rd August 1871.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, EDWARD
BURSTOW, of Horsham, in the County of Sussex, Architect, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Sixth day of February, in the year
of our Lord One thousand eight hundred and seventy-one, in the thirty-
fourth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Edward Burstow, Her special licence
that I, the said Edward Burstow, my executors, administrators, and
assigns, or such others as I, the said Edward Burstow, my executors,
administrators, and assigns, should at any time agree with, and no
others, from time to time and at all times thereafter during the term
therein expressed, should and lawfully might make, use, exercise, and
vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "A NEW OR IMPROVED
APPARATUS FOR ENABLING DRAUGHTSMEN AND OTHERS TO DRAW ELLIPTICAL CURVES
AND OTHER GEOMETRICAL CURVES AND FIGURES WITH GREATER FACILITY THAN
HERETOFORE," upon the condition (amongst others) that I, the said
Edward Burstow, my executors or administrators, by an instrument
in writing under my, or their, or one of their hands and seals, should
particularly describe and ascertain the nature of the said Invention,
and in what manner the same was to be performed, and cause the
same to be filed in the Great Seal Patent Office within six calendar
months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said Edward Burstow, do hereby declare
the nature of my said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the

page_text: following statement, reference being had to the Sheets of Drawings here-
unto annexed, and forming part of this my Specification, in which in
Sheet No. 1 A indicates a fixed horizontal arm terminating over the
centre of the apparatus in a head B, through which passes a vertical
spindle, to the upper extremity of which is fixed a handle C, by means
of which motion is given to the apparatus. The lower extremity of the
said spindle carries a bar D, which passes through the sliding piece E
which is clamped to any part of the bar D by the screw F.
G, G, are two bars forming the bed of the apparatus, each having on
the side facing the other a deep groove through its entire length, in
which grooves works the slide H, which I prefer to make about the same
length as the whole apparatus, and which near its centre is pierced by
a slot or opening through which the short slide I carrying the moving
centre of the instrument works on the bars G, G. At K on the slide H is
jointed the arm L, which together with the arm M, which is attached to L
at a point equidistant from either end, supports the wheels N, O, P, Q,
and carries the slide I with the moving centre backwards and forwards
upon the bars G, G. The wheels N and O are connected together by a
chain band or cogs according to the size and requirements of the instru-
ment, and the wheels P and Q are similarly connected. O and Pare
either made in one piece, or are firmly fixed on the same axle. N is
firmly fixed on an axle fixed to and forming part of the sliding piece E,
and the wheel Q is fixed to and gives motion to the axle forming the
moving centre of the apparatus, which passing through the slide I
terminates in a disk on which fits the hollow piece R with the clamping
screw S, by means of which a circular adjustment is obtained, and the
direction of the transverse diameter of the ellipsis varied at pleasure.
The bar T carries the pencil, pen, or point, and passes throug the
piece V, to which it is clamped by the screw W. X, X, are parts of
the frame supporting the apparatus, and are cut away at x, x, for the
reception of the bar T. Z, Z, Z, Z, are screws pointed at the lower
extremity, serving to hold the apparatus firm while it is being used, and
if necessary to bring it accurately into the plane of the paper.
The method of using this apparatus is as follows:-It having been
placed on the surface on which it is desired to describe an elliptical
curve or curves, and the handle C being turned, the wheel N together
with one end of the arm L is carried in a circle round the centre, the

page_text: other end at K carrying the slide H backwards and forwards on the
bars G, G, while the wheel N being carried once round on its own axis
by each revolution of the apparatus communicates the same motion to
the wheels O, P, and Q, and so to the bar carrying the pen, point, or
pencil U, which being thus caused to perform a motion round a centre,
while that centre performs a motion to and fro along the bed of the
apparatus, describes an ellipsis the shape of which approaches and at
last becomes a circle as the wheel N is brought nearer to or under the
centre of the head B, or becomes narrower, and finally a straight line or
point as the pencil is brought nearer to or under the centre of the
wheel Q. By reversing the direction of the bar T I am able at one
stroke to describe ellipses the conjugate diameter of which does not
exceed the distance between the feet of the instrument less the diameter
of the wheel Q, and the transverse diameter of which does not exceed
twice that distance. Ellipses of greater size I describe outside the feet
of the apparatus, and having drawn one half I reverse the apparatus
and describe the other half. In this way I can describe with a fourteen-
inch instrument, having one six and one thirteen inch pencil bar, any
ellipses whose transverse and conjugate diameters do not exceed four
feet and three feet respectively, those ellipses whose transverse and con-
jugate diameters are less than two feet and one foot respectively being
drawn without moving the position of the instrument, provided always
the difference in the diameters can in no case exceed the distance which
the slide I is capable of travelling.
For use in workshops and various uses I vary the arrangement
slightly by inverting the parts between the head B and the slide I, and
by attaching the bar D to the spindle passing through the slide I instead
of to that through the head B, and centering the end of the arm M,
which carries the wheel Q on the spindle at B instead of that at I, as
shown in the Sheet of Drawings, No. 2. If desired the wheels and chains
may be dispensed with, and the pencil bar be moved directly by the
hand. I also adapt the same apparatus, made stronger and slightly
modified, to the turning lathe for elliptical turning.
Having now fully described and set forth the nature and object of
my said Invention for "A New or Improved Apparatus for Enabling
Draughtsmen and others to Draw Elliptical Curves and other Geo-
metrical Curves and Figures with Greater Facility than heretofore,"

page_text: together with the best means I am acquainted with for carrying the
same into practical effect, I would remark in conclusion that I do not
confine myself to the exact arrangement of mechanism herein-before
described, as the same may be variously modified without departing from
the nature of my Invention; but that what I consider to be novel and
original, and therefore claim as the Invention secured to me by the
herein-before in part recited Letters Patent is,―
First. The construction of an apparatus for producing elliptical curves
wherein a bar carrying a pencil or cutter rotates round a centre of
motion, which is at the same time carried to and fro with a reciprocating
motion, as herein-before described.
Second. The construction of a modified form of the above apparatus,
as shown in the Drawings on Sheet 2, and in the words of reference
accompanying that Sheet.
In witness whereof, I, the said Edward Burstow, have hereunto set
my hand and seal, this Second day of August, in the year of our
Lord One thousand eight hundred and seventy-one.