IMPROVEMENTS IN MATHEMATICAL DRAWING INSTRUMENTS
Year: 1866

page_text: PROVISIONAL SPECIFICATION left by William Ford Stanley at the Office
of the Commissioners of Patents, with his Petition, on the 5th March
1866.
I, WILLIAM FORD STANLEY, of 3 and 5, Great Turnstile, Holborn, in the
County of Middlesex, Mathematical Instrument Maker, do hereby declare
the nature of the said Invention for "IMPROVEMENTS IN MATHEMATICAL DRAWING
INSTRUMENTS," to be as follows:-
This Invention has for its object the construction and improvement of
instruments to be used to produce geometrical curves and radial lines
therefrom, and to transfer positions or apparent positions of curves or other
objects to drawings. The whole improvements may be included in a set of
architectural drawing instruments.
My first improvement consists in additional parts to an instrument used to
produce the geometrical curves known as the hypocycloid and epicycloid, and
termed a geometrical pen; this instrument as previously constructed consists
of a frame which stands upon T feet, and supports a kind of bed which
revolves upon one end as a centre. Upon this bed is fixed two or three
axles, each of which admits a cog wheel to be placed upon it, so that the
several cog wheels gear one into the other. Upon the second or third
wheel from the centre of the instrument a small bed is constructed so that a

page_text: head may be clumped and adjusted upon it, and this head is adapted to carry
an ink or pencil marking point. In my improvements in the geometrical
pen, instead of the head on the second or third wheel carrying a marking
point it carries one end of a bar. The bar crosses horizontally over the centre
of the axis of the instrument, and is supported at the opposite end in a sliding
fitting. The ink or pencil head is adjusted upon this bar. The improvement
is the addition of this bar and its sliding fittings to the instrument.
My second improvement consists in an additional part to an instrument
used to produce the geometrical curve known as the conchoid, and here
called a conchoid pen. The original instrument, as invented by Nicomedis,
consisted of a bed in the form of the letter L. Upon the horizontal arm of
the L, near the extreme end, was placed a fitting adapted to admit a bar to
slide through it. At the opposite end of the bar a head was constructed to
carry a marking point. Near the marking point was constructed a stud,
which guided the marking point along near the vertical side of the L bed.
The instrument so constructed was -adapted to strike the small portion of a
conchoid necessary to produce the outline of a doric column. My improve-
ment in the conchoid pen consists in marking the bed in form of the letter T
instead of L, whereby the marking head may pass over the centre and produce
the perfect conchoid. The heads of my conchoid pen are also constructed to
slide in grooves, and are clamped and adjusted where required, or they may
be clamped so as to form what is known as a semi-elliptic trammel, which
produces the semi-ellipse. The improvement is the addition of the extra arm
to give the base the T-form and the sliding fittings to the bar.
My. third improvement consists in additional parts to a geometrical.
instrument used to produce curves and radial lines, principally in perspective.
drawing; and termed a rolling centrolincut. The instrument as originally
constructed consisted of a rectangular bed, which was supported upon two
changeable wheels of different sizes upon one axis, or by 3 wheels of similar
size which were made to radiate from a centre. The pen, when the, instru-..
ment was used to produce curves was fixed at one end of the bed. Either.
construction of this instrument raised the bed unequally above, the surface of
the drawing, so that a radial line could not be produced with certainty. My.
improvenient consists in making one of the bearings to adjust so that when
a large wheel is placed upon the axis the bearing may be raised so as to let
the bed. remain level, and instead of fixing the pen, upon the end of the
instrument I carry out a bar, upon which the head to carry the pen slides;
this bar I divide so as to give a required, radius to the curve produced by the
pen. One of these additions may be used without the other.

page_text: My fourth improvement consists of additional parts to an ordinary pair of
compasses to be used for giving the perspective position of objects by reflection.
It may be thus explained -If an ordinary pair of compasses be taken, and
a mirror fixed vertically upon the side of the head joint so as to move and
follow the opening of the compasses, and another glass, half the surface
of which is silvered to form a mirror, and the other half plain, be placed
opposite the first mirror and fixed upon an arm projected from one leg of the
compasses, the other reflections in the first mirror will be again reflected in
the second or opposite mirror. If an eye piece be fixed upon the same leg
of the compasses as the first mirror, by looking through this eye piece the
reflected image may be seen simultaneously with a direct observation through
the plain glass, and by this observation the direct and reflected image will
appear superimposed, the opening of the compasses at the time representing
the angle the two objects bear to each other; in relation to the observer
this optical principle is employed in a mathematical instrument termed a
sextant.
My improvement consists in adding the optical principle of the sextant to
an ordinary pair of compasses, by means of which it is converted into a
geometrical drawing instrument, as any positions of objects may be taken with
it and directly transferred to the paper by means of intersecting arcs. This
compass may also be used for astronomical purposes.
My fifth improvement may be considered as an addition to the fourth, and
may be thus explained :-If a pair of compasses be taken, the legs of which
are parallel bars, and a point be projected vertically from the joint by making
a head which carries a point or pen slide on each of the parallel bars, a
compass will be made that would take the position of any three points; thus
this instrument will appear as a beam compass jointed in the centre with a
point projected from the joint, for which purpose I claim the originality of this
arrangement as well as for its application to the optical pen described, where
it will be applied only to alter the perspective scale.
These five several improvements are each described separately for clearness,
as adapted to different instruments in the set, but I also claim the originality
of these improvements combined in any way upon the same instrument or
any two or more combined on one instrument. The first improvement I also
claim if applied to engraving or adapted to a lathe for engine turning.