An Instrument for Enabling Drawings to be Produced in Accurate Perspective.
Year: 1888

page_text: An Instrument for Enabling Drawings to be Produced in Accurate
Perspective.
I, JOHN VARLEY, of 10 Abbey Road, Saint John's Wood, in the County of
Middlesex, Artist, do hereby declare the nature of said invention to be as
follows:-
My invention relates to an instrument to enable any one to produce a drawing in
accurate perspective, without the use of long straight edges, or. threads, and without
previously ascertaining the vanishing point. By the use of this instrument one can
also fix on a convenient distance for a vanishing point, and work the drawing without
the necessity of ruling lines to it.
This instrument is likewise particularly useful for out of door work where long
straight edges, or threads, cannot be conveniently used.
My said instrument is formed as a jointed rule, with two limbs, one limb being
shorter than the other, so that when the instrument is opened to its fullest extent the
two limbs form an exact right angle, the inner end of the shorter limb abutting
against the inner side of the longer one at the pivotted or jointed end. On each
limb of the instrument, and on both sides thereof, is a graduated scale, and each limb
is provided with sliding pointers or verniers formed as clips. Or these pointers
or verniers may be arranged to slide upon the limbs in any convenient manner.
To use the instrument, say by way of example for the production of a perspective
drawing where the inclination to the horizon of one line is given, I proceed in the
following manner :-
call
I place one limb of the instrument, which for purposes of description I will
A," accurately upon the horizon and open out the other limb, which I will
call "B," until its inner edge touches the top of a perpendicular line, marked off in
any number of divisions and drawn upon the said horizon.. 1 then accurately mark
the position of this perpendicular by one of the sliding pointers. I next let fall a
second perpendicular line on the horizon at any desired point of the inclined line, and

page_text: then shift the rule, keeping it open at the same angle, until its inner edge cuts the
second perpendicular. I then place the second pointer under it and now shift the rule
back to the first position and bring the limb "B" down to any division on the first
perpendicular. On now moving back to the second position the point on the second
perpendicular which is cut by the limb "B," will be in perspective with the first
division on the first perpendicular.
This manipulation is then repeated for all the divisions on the first perpendicular.
For lines below the horizon the rule or instrument is reversed, the sliding
pointers being kept in the same position as for the lines above the horizon, and I
proceed in the same manner as above set forth.
Dated this 28th day of April 1888.

page_text: COMPLETE SPECIFICATION.
An Instrument for Enabling Drawings to be Produced in Accurate
Perspective.
I, JOHN VARLEY, of 10 Abbey Road, Saint John's Wood, in the County of
Middlesex, Artist 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, reference being had to the accompanying drawings and to
the letters and figures marked thereon, that is to say :—
My invention relates to an instrument or ruler to enable anyone to produce a
drawing in accurate perspective, without the use of long straight edges, or threads,
and without previously ascertaining the vanishing point. By the use of this instru-
ment one can also fix on a convenient distance for a vanishing point, and work the
drawing without the necessity of ruling lines to it.
This instrument is likewise particularly useful for out of door work, where long
straight-edges, or threads, cannot be conveniently used.
And in order that my invention may be readily understood, I proceed to describe
the same with reference to the accompanying drawings which shew my construction
of instrument, and in which:
Fig. 1 is a view showing the same closed.
Fig. 2 is a view showing the same opened.
Fig. 3 is a perspective view detached, of one of the pointers or verniers I employ,
and
Fig. 4 shows one. mode of using the instrument.
My said instrument is formed as a jointed ruler with two limbs or arms A, B, hinged
or jointed together at a. The limb or arm A is shorter than the limb or arm B,
as shewn in fig. 1, so that when the instrument is opened to its fullest extent, as seen
in fig. 2, the two limbs or arms form an exact right angle, the inner end of the shorter
limb A then abutting against the inner edge of the longer limb B. On each limb or
arm of the instrument, and on both sides thereof, is a suitably graduated scale, and
each said limb is provided with two sliding pointers or verniers V V₁, VV', respectively.
These pointers or verniers may be formed as clips, as shewn in fig. 3, or they may
be arranged to slide upon or travel over the limbs or arms in any other suitable
manner.
To use this instrument say, by way of example, for the production of a perspective
drawing where the inclination to the horizon of a line being given, it is desired to put
in perspective all the other lines tending to the same vanishing point, I proceed as
follows:-
Let 1-3 represent the inclination of the top of a building towards a vanishing
point somewhere on the horizon, and 1-2 one of its sides. It is required to draw
lines from 5, 7, 9 and 2 in perspective with the line 1-3.
For this purpose, I place the limb or arm B of the instrument with its inner ed ge
on the horizon, and then move up the arm A until its inner edge touches point 1,

page_text: I then slide the pointer or vernier V along the arm B until its point is immediately
under the perpendicular falling from 1. I now shift the instrument along the horizon,
as seen in dotted lines fig. 4, keeping it open at the same angle until the inner end of
the limb or arm A touches the point 3, and I place the pointer or vernier V1 on the
said limb or arm B with its point under the perpendicular falling from 3. (I may
here state that any point may be taken on the line drawn from 1, through 3 towards
the vanishing point, if a perpendicular be drawn from it to the horizon). I then
move back the instrument to its first position, that is, with the pointer or vernier V
on the line 1-2 and bring down the arm or limb A until its inner edge touches the
point 5. I then shift the instrument along the horizon, as before, that is until the
pointer or vernier V' is upon line 3-4, and 1 mark. where the inner edge of the limb
or arm A cuts the perpendicular 3-4 which will be at point the 6. A line now
drawn from 5 to 6 will be in true perspective with the line 1-3. I next proceed
in the same way to draw in the lines 7-8, and all other lines above the horizon.
For lines above the horizon, I keep both pointers or verniers in the same positions,
as just previously used, and turn the instrument over, keeping the inner edge of the
limb or arm B on the horizon. I now close the instrument until the inner edge of
the limb or arm A touches point. 2, then, without. disturbing the limb Vor arm A,
I shift the instrument, as before described, until the inner edge of the limb or arm A
cuts the perpendicular 3-4 which it will do at the point 4; 1 now draw 4-2 and
it will tend to the same vanishing point as the line 13. I then proceed in the
same manner for the line 9-10, and for all the other lines below the horizon.
·
In working out the problem above given, I do not employ the pointers or verniers
upon the limb or arm A, they being slidden along the said arm to either end thereof,
so as to be out of the way.
4
Having now particularly described and ascertained the nature of my said.
Invention and in what manner the same is to be performed I declare that what I
claim is -
:-
1
The herein described instrument or ruler formed of the two limbs or arms A, B,
articulated at a, and adapted to form together an exact right angle, when opened
to their full extent, the limb or arm A being shorter than the limb or arm B, and
both furnished with pointers or verniers V V₁, capable of being shifted along said
limbs or arms which are provided on their upper and under surfaces with a suitably
graduated scale, substantially as specified and shewn and for the purposes set forth..
Dated this 11th day of January 1880