An Instrument for Facilitating the Teaching of the Projection of Straight and Curved Lines, Circles, and of the Plane Figures and Solids Bounded by such Lines.
Year: 1892

page_text: Date of Application, 1st Dec., 1892-Accepted, 7th Jan., 1893
COMPLETE SPECIFICATION.
An Instrument for Facilitating the Teaching of the Projection of
Straight and Curved Lines, Circles, and of the Plane Figures and
Solids Bounded by such Lines.
I, HENRY WILLIAM BROWN residing at 90 Farrant Avenue Wood Green
London Middlesex England Certificated Teacher & Metal Plate. Worker 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:-
I construct of metal, preferably iron and brass, or of wood and metal, an
instrument whereby a teacher may clearly demonstrate to scholars the principles
on which, and the methods by which the plans and elevations of lines, plane figures,
and solids, are projected upon the vertical & horizontal planes, and I construct it
in the following manner :-
I take a suitable base of metal or wood as A. Into this is screwed a standard B,
consisting of an upright round metal rod, about 18" long, and 3" in diameter.
Working freely upon B is a socket C, consisting of two hollow cylinders, joined
so as to form what is technically termed a tee. Through the vertical cylinder
of the tee, a " hole is drilled, & threaded, & fitted with a thumbscrew D.
D, impinging on B secures the socket C and whatever it carries, at any desired height
on the rod B. The horizontal cylinder of the tee is threaded, and has screwed
into it the arm E, which is a round metal rod 7" long and 3" thick. The socket F
is screwed on to the other end of E. The socket F consists of 2 equal cylinders, both
threaded on the inside and forming the well-known elbow-joint.
Into the other
outlet of the elbow F, the support Ğ is screwed. G consists of a metal rod of the
same thickness as B and E. It is about 6" long. Its lower end is threaded for
about 1" and fitted with a nut H. G turns freely in its socket F and is instantly
secured at any desired point by the nut H. At its upper end, G is either beaten
out into a disc about " in diameter, or, the top of G is threaded and a socket
bearing a disc is screwed on. The disc is drilled through its centre, the hole being
"in diameter. This hole is fitted with a screw I, which has a fly-nut K. The
screw I, is the point of attachment of the rods, rings, &c., to be used in teaching
the projections herein-before mentioned.
L is a metal tube or rod, preferably of brass, about 12" long and " thick. To
its centre is attached the metal plate M, which, near its lower end, has a slot N cut
in it. N is of such a width as to let screw I freely pass through it. At each end
of the bar L, and on its upper surface, a small cleat hook is fixed, and a shallow.
groove filed.
O is a metal ring 8" in diameter and about " thick. To it is attached a plate P,
similar to M, and having the slot Q similar in size and shape to the slot N. The
upper part of plate P, is, however, bent at right angles, and the edge curved out to
coincide with the curvature of O. To the upper surface of O, 8 small cleat hooks are
attached, similar to those on L.
The rod L is intended for use in demonstrating the projections of straight lines.
To attach it to the support G, the fly-nut K is unscrewed a short distance, and the
slot N of the plate M, slipped over the screw I, between the nut K & the disc at
the top of G. The nut is then screwed up, & holds the plate carrying the rod L
securely against the disc. By slightly loosening the nut, the rod is permitted to
move freely in a vertical plane. It can therefore be secured in any position with
respect to the horizontal plane, viz., either parallel to it, or vertical to it, or inclined
at any angle to it. Having obtained the desired position with respect to the
horizontal plane, tighten up the nut K. Now, on loosening the nut H, the

page_text: support G with the rod attached can be moved freely in a horizontal plane, and
therefore the rod can be placed in any desired position with regard to the vertical
plane, and can be secured in that position by the nut H.
.
Take small pellets of metal, as X. Attach them to threads of ordinary white
sewing cotton Y. Take one of the threads so prepared and pass it into the shallow
groove at one end of the rod L. Shorten the thread till the pellet X causes it to.
hang taut. Then fix the free end of the thread to the cleat hook Z. The distance
between the pellets is the projection of the rod L on the horizontal plane.
In showing the projection on the vertical plane, the square R is used. It consists
of 2 bars of metal about 3" long, " wide and " thick, joined in the form of a T.
In the centre of the horizontal bar of the T, a hole is drilled and a straight rigid
wire, S, is inserted & fixed in it. The wire S is about 18" long and about " thick.
It stands at right angles to the plane of the T. In the vertical bar of the T, a
small knob is fixed for convenience in holding. In marking the projections of points
on the vertical plane, the square R is held flat upon the plane, with the wire S
projecting at right angles to the plane. The square is moved along the vertical
plane, till S touches that point whose projection is sought. This projection is shown
in position by that end of the wire, which is in the T of the square.
The circle O is secured to the standard G in a similar manner, and the plans
and elevations of its points are shown by the threads & pellets, and square R, as in
the case of the rod L.
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 :-
(1) An instrument by which a teacher may ocularly demonstrate the principles
involved, and methods used, in the projection of lines, plane figures, & solids.
(2) By means of this instrument, together with its parts, the rod L, and the
ring O, lines, and plane figures (circular) may be shown in any position with respect
to either or both of the coordinate planes of projection.
(3) That those parts of the instrument which represent the actual lines & figures
under demonstration, are so constructed, that the projectors, which have to be
drawn to obtain the plans and elevations of such figures, are ocularly represented
by cotton threads, and rigid wires (square R), and that the positions of the
projections of points in them are marked by the pellets and the wire S of the
Square R.
(4) That if the plate M or P be attached to the wire models of solids, (usually
found in schools where projection or solid geometry is taught), they may become
available for use with this invention, and by its means, the projections of the lines
which bound their faces, may be ocularly determined.
Dated this 28th day of November 1892.
HENRY WILLIAM BROWN.