Improvements relating to Set Squares for Teaching Drawing, and for other purposes.
Year: 1895

page_text: Date of Application, 27th May, 1895
Complete Specification Left, 19th Feb., 1896-Accepted, 4th Apr., 1896
PROVISIONAL SPECIFICATION.
Improvements relating to Set Squares for Teaching Drawing, and
for other purposes.
I, JAMES WILLIAM LADNER, of 21 Sundorne Road, Old Charlton, in the
County of London, Schoolmaster, do hereby declare the nature of this invention
to be as follows:-
The invention consists of a set square with smaller angles of 45° each, having a
quadrant cut out of the body of the triangle, the straight sides of the quadrant
being parallel to, and equidistant from, the rectangular sides of the set square.
The edges of the set square and the straight edges of the quadrant are subdivided,
and degrees are marked on the arc. A straight line is drawn through the two
right angles, marking the centres of the arc and longest side of set square. See
Fig. 1 of drawing which is a plan of the instrument.
The addition of a movable index may be introduced. In this case, the angle of
the quadrant would not be cut out, but would be shown by a small hole, around
which the index would revolve freely as in Fig. II.
The instrument may be of any size, divided according to any system, and be
made of any suitable material.
The objects to which the invention may be applied are-
1) For teaching model drawing.-By holding the instrument so that one edge of
the quadrant covers the nearest vertical edge of the object, and the rectangle is in
line with the angle of the object, the vanishing angle is shown on the are where_it
strikes, or if short, by being covered by index, or piece of string held at A. By
holding the set square at such a distance from the eye that the longer line of
object coincides with radius of arc, the proportional length of the vanishing line
is shown.
2) For teaching solid geometry.-If the line A B C is placed on the ground
line, a point can be projected from the horizontal to the vertical plane, or vice versa
with one stroke of the pencil instead of with two as now practised.
3) In teaching the construction of regular figures-for instance to draw a
hexagon on a given line. Produce the line either way. Place the rectangle of
quadrant at the end of given line so that one edge coincides with produced portion.
Mark off an angle of 30° from the other edge of quadrant. Through this point
draw second side of hexagon, and so on.
4) For showing vertical and horizontal lines.-By holding plummet at A and
making it coincide with A B C, the two lines are shown by plummet, or index, and
hypotenuse of set square.
5) For testing slope of surfaces.-Place hypotenuse on surface, so that
rectangles are above it. Hold plummet at A, then the string of the plummet
or index, will show a level surface if it strikes A B C or angle of slope, by the
angular distance from it.
5715105

page_text: Improvements relating to Set Squares for Teaching Drawing, and
for other purposes.
I, JAMES WILLIAM LADNER, of 21 Sundorne Road, Charlton, in the County
of London, Schoolmaster, 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 :-
The invention consists of set square with smaller angles of 45° each, having a
quadrant cut out of the body of the triangle, the straight sides of the quadrant
being parallel to, and equidistant from, the rectangular sides of the set square.
A smaller arc, half the radius of larger arc, may be made to span the opening.
A straight line is marked from the outer right angle to the centre of the longest
side of the triangle. A straight line is marked from the inner right angle
perpendicular to each of the outer rectangular sides.
A hole is pierced in the line joining the two right angles.
The edges of the set square, and the straight sides of the quadrant are
subdivided, and degrees are marked on the arc.
The instrument may be of any size, divided according to any system, and made
of any material.
The drawing represents a plan of the instrument marked in inches and parts of
an inch. BGH is the quadrant cut out of the body of the set square. IJ is the
second arc which may be made to span the opening. ABCD marks the centre
of the instrument. BE, B E' mark the directions of the rectangular sides of
the quadrant towards the rectangular sides of the set square. F is the hole
pierced on line A B for fixing a plummet to hang from B. The plummet is fixed
by making a loop at the end of its string, passing this loop through the hole F,
threading the plumb-bob through the loop, so that when the string is tightened,
the plummet may be suspended from B.
The objects to which the invention may be applied are-
1) For teaching drawing from models. By holding the instrument so that one
edge of the quadrant visually coincides with the near vertical edge of the object,
and the right angle is in visual line with the near angle of the object, the direction
of the vanishing side is shown on the arc it strikes, or towards which it tends.
By holding the set square at such a distance from the eye that the longer side of
the object visually coincides with the radius of the quadrant, the proportional size
of the vanishing side is shown.
2) For working problems in solid geometry.-If the line ABCD is placed
on the ground line, a point can be projected from the horizontal to the vertical
plane, or vice versa, with one stroke of the pencil.
3) For drawing regular geometrical figures.-By drawing one side of the
required figure, placing B on the end of the side so that BE, or B E' covers a
portion of the side, the direction of the second side can be marked off from
the arc according to the formula (1
sides.
4
-
72
90°, where n is the number of required
4) For showing vertical and horizontal lines. By causing the plummet line to
cover A B C D, the hypotenuse shows horizontal, and the plumb line vertical
direction.
5) For testing the slope of a surface. By placing the hypotenuse on the
surface to be tested, so that the plane of the instrument is vertical, the slope of
the surface will be shown on the arc by the angular difference between the
plummet and line C D.

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 :-
1. Improving the 45° set square by making a hollow quadrant in the body of it
as described and drawn.
2. Marking centre line across the instrument as described and drawn.
3. Piercing hole to enable plummet to be fixed as described.
4. Marking lines so that the instrument may be used for making regular
geometrical figures.
Dated this 19th day of February 1896.
JAMES WILLIAM LADNER.