Improvements in Apparatus for Use in Teaching Geometry and Perspective, or the Projection of Points, Lines, and Planes.
Year: 1895

page_text: Date of Application, 13th Aug., 1895
Complete Specification Left, 13th May, 1896-Accepted, 20th June, 1896
PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Use in Teaching Geometry and
Perspective, or the Projection of Points, Lines, and Planes.
I, THOMAS HUTTON of 62 Lord Derby Street, Blackburn in the County of
Lancaster, Science Teacher, do hereby declare the nature of this invention to be
as follows:
66
In the teaching of geometry and perspective or the projection of points, lines
and planes, two boards hinged together are at present usually employed to represent
when placed at an angle of 90° to each other the horizontal or ground" and
vertical or "picture" planes of projection, the "ground" plane being turned down
to flatten the field when the desired projections have been made or indicated.
Other detached planes for use in conjunction with the hinged planes are taken up
as required and held in the desired position by hand. Now, as the "ground" plane
is usually arranged a little below the point of sight of the students it follows that
when it is turned down, it almost entirely disappears from the students' view.
Moreover the use of the detached planes is extremely troublesome.
"
The present invention consists in providing means whereby the "ground" and
vertical planes may, when required, be flattened and simultaneously elevated in a
simple and convenient manner, thus bringing the whole field readily into view, and
in providing means whereby the auxiliary detached planes may be connected to
the "ground and vertical planes so as to be readily adjustable to any desired
angle to either or both of said planes and fixed rigidly and with facility in the
desired positions, whilst still allowing of all the planes being flattened simultaneously
on their intersections with one another as before described when the desired
projections have been made or indicated.
Another feature of the invention consists in marking the surfaces of all the
planes with a number of intersecting lines parallel to their edges thus dividing the
planes into numerous parallelograms, the lines on the "ground" and vertical planes
being some parallel to and others at right angles to the axis of the hinged connection
of the two planęs.
The invention comprises an apparatus for the teacher's use as will be now
described, and a similar but smaller and simpler apparatus for the individual use
of the students.
The improved teachers' apparatus consists of two rectangular semi-circular or
other suitably shaped planes of wood or other suitable material hinged together at
corresponding edges, and with their surfaces divided into squares or rectangles by
lines parallel and perpendicular to the hinge line. The front edge of the "ground
plane is hinged to a suitable structure which serves as a table or stand for the
apparatus and which may be formed as a cabinet for storing the various accessories
used by the teacher. Behind the other or vertical plane and connected thereto is
a batten or the like having its lower end projecting as far as, or any convenient
distance below, the lower surface of the "ground" plane when the two planes are
at right angles. Another batten is hinged at one end to the lower end of the
vertical batten and at the other end to the stand or other structure in such a
manner that the plane containing the axes of the lower batten hinges is parallel to
the plane containing the axes of the "ground" plane hinges, the distance between
the two axes of the former being equal to that between the two axes of the latter.
'

page_text: On taking hold of the vertical batten or grasping a handle provided for the
purpose at some suitable point the vertical plane may be lifted upwards and
forwards, the "ground" plane simultaneously rising at its rear edge until both
planes are flattened and elevated, which position they will retain until again
returned to a position at right angles to each other in which the "ground" plane
will rest flat upon the stand. Suitable buttons or other devices may be provided
by which the batten may be locked and the planes secured rigidly when in their
elevated position.
In order to allow of the projection of long objects I may provide the said planes
with side extensions adapted to be hooked or otherwise connected to them and in
such cases arrange sliding supports below the ground and behind the vertical planes
to give rigidity to the extensions.
To represent planes perpendicular or inclined to one or to both of the planes,
two lines are marked, one on each plane in such a manner that said lines and the
hinge line of the two planes tend all to one point. An auxiliary plane such as a
board or sheet of transparent or other suitable material is so constructed that two
adjacent edges thereof fit to the said lines, means being provided whereby these
edges are capable of hinging over either of the lines, the line to which it is hinged
being as nearly as possible the axis of the hinge. The form of this plane may be
either a parallelogram or a sector or may partake of both. If a parallelogram, the
edge opposite to its hinged edge is split or suitably grooved to receive a rod
adapted to work freely therein. If a sector, the groove is formed along the
circular edge. To the other of the two lines mentioned above is hinged a bracket
to which one end of the aforesaid rod is pivoted so as to be capable of revolving
through two right angles or 180°. This rod is straight when the plane is a
parallelogram and curved when it is a sector in order to correspond to the groove
on the plane. This arrangement by the weight of the, material keeps the vertical
"ground" and auxiliary planes rigidly in position, but by merely raising the batten
or handle as before described all the planes may be simultaneously elevated and
flattened into one plane vertically over the front hinged connection of the "ground"
plane to the stand.
"
Any suitable form of hinged connection between the auxiliary plane and the
two main planes may be adopted, but I prefer to employ flat rods to lie flat on the
two aforesaid lines of the main planes and hook their ends to overhang the edges
of the planes, a perforation or the like at the intersection of the two lines affording
a ready-means of attaching the inner ends of said rods to the main planes whilst
their outer ends may be provided with milled screws or other clamping devices to
grip the edges of said planes. This provides a ready means of adjusting the
auxiliary plane to any angle to either or both of the main planes and to fix it in
such position, without interfering with the flattening of the field as before
described. One of these flat rods will be provided with sockets or eyes adapted to
engage similar devices on the edge of the auxiliary plane to produce a hinge by
means of pins or the like passed therethrough, whilst the other rod carries the
bracket of the rod which engages in the groove of the plane as aforesaid.
Numerous auxiliary planes are provided of different forms and material as
required. I prefer to make them for some purposes of transparent material, and in
every case prefer to divide their surfaces into parallelograms by lines parallel to
their fitted edges, although it is obvious that the apparatus may be used without
so lining any of the planes.
As before stated I provide for some cases transparent auxiliary planes preferably
consisting of a glass panel in a wooden frame, and for this and other cases where
the weight of the plane is too great for the rod which works in the groove, I may
do without said rod and provide instead an antifriction roller on the lower edge of
the plane to work on the ground plane.
The students' apparatus comprises a "ground" and a vertical plane of cardboard
or other material lined as in the teachers' apparatus and hinged together by a strip
of tough flexible material or as desired, also a number of lined auxiliary planes of

page_text: different forms such as right angled, acute-angle! and obtuse angled as used in the
teachers' apparatus, and several frames grooved to receive two adjacent edges of any
one of the planes. These grooved frames are preferably formed of sheet metal cut to
the desired angle and bent longitudinally to a U section to form the groove. Strips
of elastic material provided for the purpose are placed in the grooves and their ends
connected together at the rear of the main planes by hooks or buttons or like
devices after the frames have been placed on the face of the main planes, a suitable
perforation being made at the centie of the hinged connection of the main planes
to allow of the elastic being passed therethrough. The elastic may however be
hooked directly on to the planes. Auxiliary planes placed in these frames may be
set to any angle to either or both the main planes, as the elastic loop is readily
movable around the periphery of the latter, and the student can readily change the
planes as required.
The transparent planes for the students' use I prefer to make of celluloid lined
as before stated, and I provide the student with paper or other discs cut to
geometrical profiles such as squares, hexagons or elevations of solids adapted to be
placed against the plane and in order to fix them in position provide a piece of
watch spring or the like to be placed angularly across it with its two ends engaging
in the grooves of the frames.
I may also provide the student with small detached planes of angular profile for
use in determining a line or lines of given inclination in a given plane or to satisfy
other suitable well known data, and the student may be taught to make similar
planes as required of stout drawing paper.
This apparatus can be flattened into a single plane precisely as before described
with the teacher's apparatus.
By my improved apparatus anyone can trace out the plans and elevations and
other views of objects whilst the planes of projection are in their actual positions
relatively to each other, and this by the use of no other means than a piece
of suitable marking material, provided they can draw by hand only a reasonably
straight line between two points and trace an even curve through a series of
points.
In my Complete Specification I shall give several examples with illustrations of
the projection of various figures and solids.
Dated this 12th day of August 1895.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Patent Agents for the Applicant.
Improvements in Apparatus for Use in Teaching Geometry and
Perspective, or the Projection of Points, Lines, and Planes.
1, THOMAS HUTTON of 62, Lord Derby Street, Blackburn, in the County of
Lancaster, Science Teacher, 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 :-
In the teaching of geometry and perspective or the projection of points, lines and
planes, two boards hinged together are at present usually employed to represent,
when placed at an angle of 90° to each other, the horizontal or
65 ground and
vertical or "picture" planes of projection, the "ground" plane being turned down
to flatten the field when the desired projections have been made or indicated.
Other detached planes for use in conjunction with the hinged planes are taken up
as required and held in the desired position by hand or drawing pins. Now, as the
'ground" plane is usually arranged a little below the point of sight of the students
66

page_text: Fig. 2 a side elevation of the teacher's apparatus ;
Fig. 3 is a front elevation of same showing the planes elevated and flattened;
Figs. 4 & 5 are perspective views of the apparatus showing means for attaching
and supporting the auxiliary planes ;
Fig. 4 is a front elevation of Fig. 4 showing the planes elevated and
flattened;
Figs. 6 & 7 are perspective views of the students' apparatus showing right-angled
and oblique auxiliary planes respectively.
The improved teachers' apparatus consists of two rectangular, semi-circular, or
other suitably shaped planes A, B, of wood or other suitable material hinged
together at corresponding edges H and with their surfaces divided into squares or
rectangles by lines parallel and perpendicular to the hinge line. Said lines are
preferably made by cutting a V-groove into the wood, the distance between them
The front
being about 2 inches. They may of course be painted if desired.
edge (Fig. 2) of the "
I
ground" plane B is hinged to a suitable structure G
which serves as a table or stand for the apparatus and which may be formed as a
cabinet for storing the various accessories used by the teacher.
Behind the other
or vertical plane A and connected thereto is a batten D or the like having its
lower end projecting as far as, or any convenient distance below, the lower surface
of the "ground" plane B when the two planes A, B, are at right angles. Another
batten E is hinged at one end F to the lower end of the vertical batten D and at
the other end F¹ to the stand or other structure G in such a manner that the
plane, containing the axes F, F1, of the lower batten hinges, is parallel to the
plane containing the axes of the "ground" plane hinges H, I, the distance between
the two axes of the former being equal to that between the two axes of the latter.
On taking hold of the vertical batten D or grasping a handle O provided for the
purpose at some suitable point the vertical plane A may be lifted upwards and
forwards, the "ground" plane B simultaneously rising at its rear edge until both
planes are flattened and elevated as shown in dotted lines in Fig. 2, which position
they will retain until again returned to a position at right angles to each other in
which the "ground" plane B will rest flat upon the stand. Suitable buttons such
as K or other devices may be provided by which the batten may be locked and the
planes secured rigidly when in their elevated position.
In order to allow of the projection of long objects I may provide either or both
of the said planes A, B, with side extensions A adapted to be hooked or otherwise

page_text: connected to them and in such cases may arrange sliding supports below the ground
and behind the vertical planes to give rigidity to the extensions.
To represent planes perpendicular or inclined to one or to both of the planes,
two lines at any desired angle are marked, one on each plane in such a manner that
said lines and the hinge line of the two planes tend all to one point usually the
centre of the hinge line H. An auxiliary plane C (Fig. 4) such as a board or
sheet of transparent or other suitable material is so constructed that two adjacent
edges thereof fit to the said lines, means being provided whereby one of these edges
is capable of hinging over either of the lines, the line over which it is hinged being
as nearly as possible the axis of the hinge. The form of this plane may be either
a rectangle, a parallelogram, or a sector. If a parallelogram, the edge opposite to
its hinged edge may be split or suitably grooved as at e Fig. 4 to receive a rod J
adapted to work freely therein. If a sector, the groove is formed along the circular
edge. To the other of the two lines mentioned above is hinged a bracket R to
which one end of the aforesaid rod J is pivoted so as to be capable of revolving
through two right angles or 180°. This rod J is straight when the plane is a
parallelogram and curved when it is a sector, in order to correspond to the groove e
on the plane. This arrangement by the weight of the material keeps the vertical
"ground," and auxiliary planes rigidly in position, but by merely raising the batten
or handle as before described, all the planes may be simultaneously elevated and
flattened into one plane vertically over the front hinged connection of the "ground
plane to the stand, as shown in Fig. 44, the rod J swinging backwards and
downwards.
[
"
Any suitable form of hinged connection between the auxiliary and the two min
planes A, B may be adopted. A convenient form consists of a flat rod f(Fig. 4)
adapted to lie flat on either of the two aforesaid lines on the main planes and having
one end f¹ hooked to engage a perforation or the like at the intersection of the two
lines, thus affording a ready means of attaching the inner end of said rod to the
main planes whilst its outer end may be provided with a milled screw g or other
clamping device to grip the edge of the plane. This, when furnished with the
fittings mentioned below provides a ready means of adjusting an auxiliary plane
to any angle to either (or both) of the main planes and of fixing it in such position,
without interfering with the flattening of the field as before described. This flat
rod is provided with sockets, bearings or eyes adapted to engage similar devices
on the edges of the auxiliary planes to produce a hinge by means of a pin 1 or the
like passed therethrough. Another rod with similar clamping device whereby it
may be set to any angle carries the hinged bracket R of the rod J which engages
in the groove of the plane as aforesaid.
h
The rod with the hinged connection to the auxiliary plane C is usually attached
to the "ground" plane B, whilst the other rod carrying the bracket R and hinged
rod Jis attached to the vertical plane A as shown in Figure 4, but it is evident
that such arrangement may be reversed, in which case the rod J and its connections
may be dispensed with and the lower edge of the auxiliary plane be allowed to run
on the "ground" plane, antifriction rollers being preferably arranged on the edges
of the auxiliary planes.
or
If however it be desired to dispense with the rod J altogether, the rod f may be
hinged to the edge of the auxiliary plane and clamped to either the "ground
the vertical plane, a suitable clamping device being attached to it to hold the
plane Cat the desired angle to the plane to which it is hinged. This latter is the
preferable form of hinged connection for the planes as it reduces the number of
loose parts, facilitates manipulation and enables the planes to be made thinner
thereby lessening their weight and approximating more closely to the theoretical
plane. This form of hinged connection is shown in Figures 1, 3 and 5. In these
figures the flat rod f adapted to lie on the "ground" or vertical plane has a milled
screw g and hooked end f' as before described whereby it may be clamped in any
desired position, the hinged connection to the auxiliary plane being made by means
of the pin and one or more sockets or eyes h. On this pin a semicircular

page_text: bracket Q, and a clips with milled screw a and clipping groove b (Figures 3 and 5)
are passed. The bracket Q is attached to the pin in the position indicated, whilst
the clips is attached to the bracket Q (loosely) by means of a cheese-beaded
screw d (Figure 5) the shaft of which works in a semicircular groove e cut in the
bracket Q. The clip s is thus capable of being revolved through 180°, but may
The other
be fixed igidly in any desired position by means of the milled screw a.
end of the flat rod is provided in addition to the hook with a pin i. The
pins and are adapted to enter eyes or sockets formed on the auxiliary planes as
aforesaid so that if be withdrawn from the bearing 2 (it cannot be withdrawn
from ) any one of the auxiliary planes may be inserted with one socket on the
pin; then the pin 7 may be replaced in the bearing 2 with its end into the other
socket of the plane thus producing a hinge. If the edge of the said plane be
placed within the chipping groove of the clip 8, the plane may be secured by
means of the screw a at any angle to the horizontal plane B (or at any angle to the
vertical plane A if the plane clamp ƒ be attached to A). The bracket Q is provided
with deeply grooved pulleys v and pins t, also an elastic spring k (Figures 1 and 3)
the ends of this spring being provided with loops (metal or otherwise) one of
which is hooked onto a pin to provided on the edge of the plane C to keep the
latter against the vertical plane the other being hooked onto one of the pins t, or
(when the spring is not required) both ends may be hooked on the two pius, the.
elastic in both cases being trained round the pulleys y and under the pin l.
A screw m is provided to prevent the pin / from slipping out of the bearing h³.
Numerous auxiliary planes may be provided of different forms and material as
required. I prefer to make them for some purposes of transparent material, and in
every case prefer to divide their surfaces into parallelograms by lines parallel to
their fitted edges, although it is obvious that the apparatus may be used without
so lining any of the planes.
The most useful forms of auxiliary planes are shown in the drawings. That
shown in Figures 1, 3 and 4 is a right angled plane and is capable of representing
a plane perpendicular to either the horizontal or vertical plane and is preferably
made of wood or other suitable opaque material, one edge being provided with
sockets (preferably of metal) for the hinged connection to the main planes as
before described, and an adjacent edge with a small anti-friction roller having
an india-rubber periphery, whilst the other adjacent edge has a pin w for the
elastic spring. Another useful plane is one made of transparent material preferably
celluloid or glass in a wooden frame and having sockets on one edge and a pulley
and a pin on adjacent edges as in the case of the plane just described, and used for
the same purpose. The auxiliary plane shown in Figure 5 is of a rhomboidal
form, and may be made of wood, or of a transparent celluloid, or glass panel
within a wooden frame, and has sockets on one edge and pulleys on two adjacent
edges. When the acute angle of the socketed edge of this plane is placed at the
hinge line H of the main planes as shown in Figure 5 it represents what may be
called an acute angled plane, i.e. a plane having an acute angle between its traces;
and when the obtuse angle of the same edge is placed at H as shown in dotted
lines it represents an obtuse angled plane. The obtuse angle of this plane is
notched as shown to give clearance to the clip s.
Any of these planes if hinged to the vertical plane A at any angle will rest
with an edge on the horizontal plane B, and it will be evident that when the main
planes are flattened into one, the auxiliary plane which happens to be attached
to A will revolve into the vertical plane on its vertical trace simultaneously. It
will also automatically re-assume its original position when the main planes are
brought back again.
This is also the case if the plane shown in Figure 5 be hinged to the horizontal
plane B with its acute angle at the hinge line H. When however this plane is
hinged to the horizontal plane with the obtuse angle at H (as shown in dotted
lines in Figure 5) it is evident that the weight of the plane (instead of pressing i
against the vertical plane A as it would in the last case) will rotate it into the

page_text: horizontal plane; in order therefore to hold the plane with its edge against the
vertical plane, it is passed through the clipping groove b in the clips (it is
advisable to place all the planes when hinging them to A or B with their edges
into this groove) and held in the desired position by means of the screw a.
When
5 it is desired to flatten the planes A, B, whilst this plane is hinged to B, the screw a
should first be slacked and the plane revolved into the plane B.
If the right angled planes be hinged to the horizontal plane B to represent a
second vertical plane (as shown in Figure 1) they may be held from falling forwards
by means of the screw a. When it is desired to flatten the main planes the
0 simultaneous flattening (as shown in Figure 3) of these vertical planes is provided
for by removing one end of the elastic spring k from its pint on the bracket Q
and hooking it onto the pin wo on the edge of the vertical plane, that end of the
elastic being chosen which will cause the plane to be pulled backwards. In the
case shown in Figures 4 and 4 where the bracket R is used instead of
the bracket the rod J which supports the right angled plane C effects the
backward pull when flattening the planes.
In order to facilitate the setting of the planes C to any given angle, I prefer to
graduate the edges of the main planes A B and the semi-circular edge of the
bracket Q, the degrees being marked from 0 to 90 and 90 to 0 through two right
augles.
The students' apparatus comprises a "ground" and a vertical plane, preferably
of semicircular form, A and B (Figures 6 and 7) of cardboard or other material
lined and graduated as in the teachers' apparatus and hinged together by a strip of
tough flexible material or as desired, also a number of lined auxiliary planes C of
different forms such as right-angled, acute-angled and obtuse-angled as used in the
teachers' apparatus and means for hinging said auxiliary planes to the main planes.
A simple means of hinged connection consists in providing the auxiliary planes (as
in the teachers' apparatus) with sockets or bearings h and pins or rods to pass
freely through said bearings as shown in Figures 6 and 7. To one end of each
roda piece of elastic y (preferably doubled) is securely attached, the free ends
of the elastic carrying an eye or socket adapted to slip over the free end of the
rod 1. When it is desired to attach an auxiliary plane such as C for instance to
the main planes, one of the rods is first passed right through the perforation
provided at the centre of the hinged connection of the main planes (but not so far
as to draw the elastic through) and through the bearings along one edge of the
plane C, the elastic being then stretched under the plane B and the eye slipped
over the free end of the rod l. The planes C will thus be hinged to the plane B.
Another rod may now be passed through the central perforation and through
the bearings along the other edge of the plane C, and secured to the plane A by
means of the elastic as just described. The plane C will now be hinged to both
main planes. In some cases grooved frames shaped to receive two adjacent edges
of the planes and preferably formed of sheet metal cut to the desired angle and
bent to a U section to form the groove may be provided instead of the rois / aud
sockets h. Strips of elastic material are in this case placed in the grooves
and their ends connected together at the rear of the main planes by hooks or
buttons or like devices after the frames have been placed on the face of the main
planes and the elastic passed through the central perforation. The elastic may
however be hooked directly onto the planes.
Auxiliary planes in both the above cases may be set to any angle to either or
both the main planes, as the elastic connection is readily movable around the
periphery of the latter, and the student can readily change the planes as required.
I prefer to cover the students' main and auxiliary planes with photographer's
background to provide a washable surface enabling the apparatus to be used for
any number of problems in succession, and I attach said material to the two main
planes in one piece so as to also produce the hinged connection between them.
The transpareut planes for the students' use I prefer to make of celluloid lined
as before stated, and I may provide the student with paper or other discs cut to

page_text: geometrical profiles such as squares, hexagons or elevations of solids adapted to be
placed against the plane and in order to fix them in position provide a piece of
watch spring or the like to be placed angularly across it with its two ends engaging
in the grooves of the plane frames.
1 may also provide the student with small detached planes of angular profile 5
for use in determining a line or lines of given inclination in a given plane or to
satisfy other suitable well known data, and the student may be taught to make
similar planes as required of stout drawing paper.
The students' apparatus can be flattened into a single plane precisely as before
described with the teacher's apparatus.
By my improved apparatus anyone can trace out the plans and elevations and
other views of objects whilst the planes of projection are in their actual positions
relatively to each other, and this by the use of no other means than a piece of
suitable marking material, provided they can draw by hand only a reasonably
straight line between two points and trace an even curve through a series of 1
points.
For this purpose the lines on the planes and on a detached rectangular transparent
plane are used in a manner which will be understood by reference to Figures 1, 3
and 6, thus to make the second elevation on the right-angled plane C (Figure 6)
the right-angled transparent plane is placed flat on the plane B over the plan with
its edge against the edge of plane C, then to obtain the second elevation of a
point it is only necessary to follow up to plane C a line on the transparent plane
from the plan of the point which is to be projected and from its intersection with
plane C to follow a vertical line to intersect horizontal lines from the first elevation
of the point on the planes A and C which intersection will give the required
projection. Where however the point to be projected does not lie on one of the
lines marked on the planes, the nearest lines may be used and will be found a
sufficient guide from which to approximate the exact position of the point. The
various methods of using the apparatus for projection and mechanical drawing
generally will thus be readily understood without further illustration.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. The improvement in apparatus for use in teaching mechanical drawing, which
consists in hinging the front edge of the horizontal plane to a stand or suitable
structure and in providing the vertical plane which is hinged to the rear edge of
said horizontal plane with a link connection to said structure, in such a way that
the two planes are held at right angles to each other, whilst by lifting the vertical
plane upwards and forwards the two planes may be simultaneously flattened and
elevated substantially as described.
2. The improvement in apparatus for use in teaching mechanical drawing, which
consists in hinging the auxiliary plane or planes to either of the main planes,
whereby said auxiliary plane or planes may be flattened simultaneously with the
main planes substantially as described.
3. The application to the various planes used in teaching mechanical drawing of
a number of intersecting lines, sunken or otherwise which by the aid of the
rectangular transparent plane, enable the projections of objects etcetera to be
made with the planes of projection and other planes in their actual positions
substantially as described.
4. In apparatus for use in teaching mechanical drawing, the means for hinging
the auxiliary planes to either of the main planes and for holding them at any angle
thereto whilst permitting of a simultaneous flattening of all the planes substantially
as described with reference to Figure 4 of the accompanying drawings.
5. In apparatus for use in teaching mechanical drawing the means for hinging
the auxiliary planes to either or both of the main planes and for clamping them at
any angle thereto whilst permitting of a simultaneous flattening of all the planes

page_text: substantially as described with reference to Figures 1, 3 and 5 of the accompanying
drawings.
6. In apparatus for use in teaching mechanical drawing such as described, the
use of auxiliary planes made of celluloid with or without their surfaces marked
with intersecting lines, substantially as described.
7. The construction and combination of parts taken as a whole forming the
improved apparatus for use in teaching mechanical drawing, substantially as
described and illustrated.
8. An apparatus for the students' use in the teaching of mechanical drawing,
comprising two main planes preferably each of semi-circular form hinged together
by a textile material, one or more auxiliary planes, and means for hinging the
latter to said main planes in such a way as to hold the main planes at right angles.
to each other, whilst permitting the auxiliary planes to be adjusted to any angle,.
and permitting the simultaneous flattening of all the planes, substantially as
described.
9. In an apparatus for students' use such as described, the means for hinging
the auxiliary planes to the main planes substantially as described with reference
to Figure 6 of the accompanying drawings.
10. In an apparatus for students' use such as described, the means for hinging
the auxiliary planes to the main planes substantially as described with reference
to Figure 7 of the accompanying drawings.
11. In an apparatus for students' use such as described, the use of auxiliary
planes made of celluloid or other transparent material with or without their
surfaces marked with intersecting lines substantially as described.
Dated this 12th day of May 1896.
WM. P. THOMPSON & Co.,
Of Liverpool, Manchester, Birmingham, and London, Patent Agents.