Improvements in Models for Showing Projections, Traces, and Intersections of Lines, and for Assisting Instruction in Solid Geometry and Perspective.
Year: 1890

page_text: Date of Application, 17th Dec., 1890
Complete Specification Left, 1st Aug. 1891-Accepted, 7th Nov. 1891
PROVISIONAL SPECIFICATION.
Improvements in Models for Showing Projections, Traces, and
Intersections of Lines, and for Assisting Instruction in Solid
Geometry and Perspective.
WILLIAM MACGILL B.A. Academy House, Mid Street, Fraserburgh Aberdeen*
shire Schoolmaster do hereby declare the nature of this invention to be as
follows:-
The usual hinged folding boards are employed as co-ordinate planes. But two
diagonal catch-bars one at each end, are used to keep the planes at fixed angle.
These catch-bars carry a straight round rod fixed at right angles to both. On
this rod there slide & turn two or more short tubes each with a pinching screw
passing through its side to fix it in any position on the rod. Each of these tubes
carries, fixed at right angles to it, a narrower tube as a socket-tube. Tuto this
socket there fits accurately, so as to turn in it but keep any position given, a long
stem. This stem carries at the other end a long thin wire. This wire is mounted
on a pin or axle transverse to the stem so as to allow of the wire rotating. This
axle- or pin-mounting is made tight enough to make the wire keep any position
given it. The wires represent lines & by combination of the turning & sliding
movements of the short tubes on the rod, of the stems in the sockets & of the wires
on their axles they can be set to represent lines and angles in any possible position
with respect to the planes. The projections of such lines & angles on the planes
are marked off on the planes by means of a movable triangular flat base carrying a
perpendicular wire at one corner-this wire prolonged as a very short needle-point
below the base.
7.
Dated this 16th day of December 1890.
WILLIAM MACGILL, B.A.
COMPLETE SPECIFICATION.
Improvements in Models for Showing Projections, Traces, and
Intersections of Lines, and for Assisting Instruction in Solid
Geometry and Perspective.
I, WILLIAM MACGILL, B.A. of Academy House, Mid Street, Fraserburgh in
the County of Aberdeen, Schoolmaster, do hereby declare the nature of this inven-
tion and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement :-
Hinged boards, such as heretofore employed are used as co-ordinate planes, hori-
zontal and vertical, but, (1) they are hinged so as to close up together or open out
into one plane, or take any angle between; (2) the horizontal plane is larger than
the vertical, so as, when closed up, to leave between them a margin of about half
an inch all round the three free edges of the planes; (3) as a guard there may,
preferably be put in along each end of the horizontal plane a ledge of wood, marked
in the accompanying drawings A B C D, of such height as to stand out above the
level of that plane by as much as the width of the struts hereinafter described,
except at the outer end where it rises into a rounded end, A B projecting an inch
or two above and beyond the corner of the plane.
Next are provided two bars or struts, E F to keep the planes at any desired
angle, usually a right angle. These struts may be of wood as E F-of width equal.
to the thickness of the vertical plane, and of, thickness about half an inch, just to

page_text: fill the spaces between the ends of vertical plane when closed up, and the ledges.
If the struts are of metal they can be thinner and the space less. The struts are
hinged at E, by "bagatelle "hinges or other suitable means to the free corners of
the horizontal plane or they may be pivoted on stout pins fixed into the rounded
projecting parts of the ledges above described. The struts may be long enough to
reach the corner of the vertical plane when vertical or, preferably, to reach the
middle of its end F. Any readily adjustable form of catch may be used at the
free end of each strut, such as a slipping pin G passing through it into a hole or
holes in the end of the vertical plane, placed so as to keep the planes at the required
angle or angles.
One or
Next is provided a straight, rigid, round rod HI preferably of iron.
both ends as I are somewhat flattened so as, when inserted into oblong sockets as
at I cut in the wood or when fixed by screws passing through them, to enable the
rod to resist a turning movement. In one of these ways it is fixed, so as to be carried
by & between the two struts near their hinges or pivots, or preferably, so as to be
carried as at H I by and between the rounded ends of the ledges above described,
but as near to the edge of the horizontal plane as is possible without interfering
with the required movement of the struts, or of the vertical plane. On this rod
fitting so as to turn or slide easily, is a slider, JK a short piece of tube usually of
brass with a pinching screw L passing and working through its side and pinching
the rod so as to fix the slider in any given position. In construction, the slider or
sliders have first to be put on the rod, then the ends to be flattened then inserted
into their sockets & then the second of the struts or ledges carrying it to be fixed.
Each slider has soldered or otherwise fixed rigidly across it, a short tube MO of
same metal, wholly or partly split, to allow of accommodating itself to slight
variation of gauge without losing grip. For convenience, it is fixed on the same or
nearly the same side of the slider as the pinching screw. Into this cross tube there
fits neatly so as to turn or slide easily, and yet be held by friction in any position,
a light round rod NP which, if necessary, may be long enough to reach from the
iron rod to the edge of the vertical plane, when vertical. This rod may be of any
suitable material, as hard wood, vulcanite-or-preferably very light-metal-tubing-
as:N P. At the end, if it is of wood-or-vulcanite, is a slightly-larger and flattened.
part, with a round hole, into which fits neatly a very short wooden or vulcanite pin,
so as to turn, yet with friction enough to keep any position. If the rod is not of
wood or vulcanite, a very short tube R of metal or other suitable material may
have to be fixed across its end by soldering or other suitable-means-in-order-to-
receive the aforesaid short pin ST. Through the projecting end or head $ of this
pin, which may, if necessary be larger as S than the stem T of it a hole U is drilled,
just large enough to admit the wire, WV of any required length, to represent a
line in the demonstration or problem. The short pin may be of metal, or metal
tube or other suitable material, as well as wood, and two or more sliders J K, each
with cross tube, MO long rod N P, and wire, WV as described, may be put on to
the iron rod, according to requirements. Next, if paper is to be used on the planes,
then, in order to find and mark in the paper the projection of any point, there is
provided a projector, XY made thus: A straight rectangular strip of brass or
other suitable metal is taken, about three-quarter-inch wide and from nine to
twelve inches long. It is bent, with the lines of bend perpendicularly across it, into
the form of a short, triangular-right prism. XZb. The free-ends of the strip,
meeting accurately are soldered as at b. Into one of the angles a suitable
length a Y-not more than the width of the plane of hard perfectly straight
wire, or preferably of light angle-steel such as is used in "
paragon" umbrella
frames, is fixed by solder or otherwise so as to be perpendicular to the plane of the
triangle forming the base of the short prism above mentioned. This wire is fixed
so that its end a projects about one-twentieth of an inch below the plane of the
above mentioned triangle and this projecting part is sharpened to a very fine point
which leaves the required mark in the paper. For some uses of the model more
than one such projector may be provided.

page_text: 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 I
claim is :-
The combination, for the purposes set forth in the title hereof, of hinged boards,
as commonly used heretofore, or such as described above, with sliding universal-
jointed holders, such as above described; for retaining wires in any position, and
with projectors capable of making a mark on the paper at the projection of a point.
Dated this 30th day of July 1891.
WILLIAM MACGILL.