Improvements in T-squares or similar Drawing Instruments.
Year: 1893

page_text: Date of Application, 29th June, 1893
Complete Specification Left, 29th Mar., 1894-Accepted, 25th May, 1894
PROVISIONAL SPECIFICATION.
Improvements in T-squares or similar Drawing Instruments.
1 HENRY RAMSAY TAYLOR, of 50, George Street, Edinburgh, Architect, do
hereby declare the nature of this invention to be as follows:-
--
My invention relates to Improvements in T-squares or similar Drawing
Instruments, and has for its object to enable the user when engaged in drawing one
line, to have in view the other parts of the drawing in juxtaposition to same which
are partly covered by such drawing instrument, thereby enabling the user to work
with greater freedom and accuracy than heretofore was the case.
In carrying my invention into practice, form the underside of the blade of
a T-square, set-square, or French-curve, with a checked or sunk surface cut on the
edge and running parallel with the whole length of the blade.
In this sunk surface, is let a thin strip of transparent celluloid or other similar
transparent material, which projects some distance laterally from the sunk edge.
The outer edge of this transparent strip constitutes the ruling edge. The said
transparent strip is fixed to the recessed or sunk bed, by means of glue or other
mucilage, or by pins or other suitable fastening means.
Both sides or edges of the T-square for instance can be provided with the
transparent strips if desirable.
In lieu of fixing the transparent edge or edges to the blade of the square as
before described, I may fashion the said square with a narrow blade and fix
a broader blade of transparent material to the under side thereof, so that a margin
of the said transparent material will project laterally on each side of the blade of
the T-square.
I can, also if desirable fashion the whole blade of the T-square of transparent
material.
In the latter case I would form the central portion for the whole of its length,
considerably thicker or deeper than the sides, the under surface in every case, being
perfectly level and smooth."
Dated this 29th day of June 1893.
HUGHES, SON & Co.,
38, Chancery Lane, London, Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in T-squares or similar Drawing Instruments.
I HENRY RAMSAY TAYLOR, of 50, George Street, Edinburgh, Architect, 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 :-
My invention relates to Improvements in T-squares or similar Drawing
Instruments such as set-squares and French curves, and has for its object to enable
the user, when engaged in drawing one line, to have in view the other parts of the
drawing which are in juxtaposition to such line, and which are at the same time
partially covered by such drawing instrument, thereby enabling the user to work
with greater freedom and accuracy than heretofore was the case.

page_text: In carrying my invention into practice, I form the underside of the blade of
a T-square, for instance, with a checked or sunk surface cut on the edge and
running parallel with the whole length of the blade.
In this sunk surface is let a thin strip of transparent celluloid or other similar
transparent material, which projects some distance, laterally from the sunk edge.
The outer edge of this transparent strip, constitutes the ruling edge. The said
transparent strip is fixed to the recessed or sunk bed, by means of glue or other
mucilage or by pins or other suitable fastening means.
Both sides or edges of the T-square for instance can be provided with the
transparent strips if desirable.
In lieu of fixing the transparent edge or edges to the blade of the square as before
described, I may fashion the said square with a narrow blade, and fix a broader
blade of transparent material to the underside thereof, so that a margin of the said
transparent material will project laterally on each side of the T-square.
I can also if desirable fashion the whole blade of the T-square of transparent
material. In the latter case I would form the central portion, for the whole of its
length, considerably thicker or deeper than the sides, the under surface in every
case, being perfectly level and smooth.
In order that the said invention may be the more readily understood, I have
shewn same upon the accompanying sheet of illustrative drawings, wherein :
Fig. 1 is an elevation of a T-square according to my invention.
Fig. 2 being a section thereof on line ', whilst
20
Figs. 3, 4, and 5 are elevation, section and plan views respectively, of a
modification of the invention.
Referring to the drawings, in which like letters of reference indicate corre-
sponding parts throughout the figures,
a (Figs. 1 and 2) is a T-square of ordinary form, having its blade fashioned with
a checked or sunk surface a' formed longitudinally along the underside of the
square at the edge, of sufficient depth and width to receive a strip of transparent
celluloid or similar transparent material of the same length as the blade of
the T-square and of sufficient width to project a suitable distance laterally from the
edge of same. The outer edge of this celluloid or other strip b, constitutes the
ruling edge when in use, and the depth of the checked or sunk bed a¹ and
the thickness of the said strip bare such, as to render the lower surface of the
latter, flush with the corresponding edge of the T-square blade a.
I fix the strip of transparent celluloid into the checked or sunk bed by means of
suitable pins, in conjunction with, or without, glue or other mucilage; or any other
suitable fastening means may be employed.
To obviate the inconvenience caused by the strip of celluloid or the like, and the
wooden blade of the T-square contracting unequally through change of temperature
or similar causes, I preferably employ the mode of securing the celluloid or other
strip to the blade, shewn in Figs. 3, 4, and 5 of the drawings. In this modified
arrangement I cut or otherwise form an incision e in the blade of the T-square a
running longitudinally the whole length of same and formed at or about midway of
the height of the edge a² of the blade which incision is formed at such an angle to
the perpendicular edge a² of the blade proper, that the strip of transparent
celluloid 6 which is fitted into such incision, will have its lower corner b² of the outer
edge on a level plane with the under face of the blade a as clearly shown in
Fig. 4.
The strip of transparent celluloid or the like b, is fixed securely in the incision c,
by means of brass or other headed pins or rivets d, which pass through the upper
part of the blade a and then through the celluloid or other strip b and the lower
part of the blade.
The celluloid or other strip b, is provided along its length with a number
of oblong slots e formed in same near the inner edge, through which the headed
pins or rivets d are driven.
By providing these slots, the celluloid or other transparent strip 6 is enabled to

page_text: contract slightly in length, without affecting the wooden blade a and vice versâ, the
headed pins d preventing such transparent strip becoming loose or detached.
If found desirable, I may provide a strip of transparent celluloid or the like
along both edges of the T-square blade a, instead of only providing one as before
described.
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. The improvements in T-squares or similar drawing instruments, consisting in
providing a checked or sunk bed along the underside of the longitudinal edge or
edges of the blade, and fixing therein a strip of transparent celluloid or the like, of
such a width as to project some distance laterally from the edge of the blade
aforesaid, substantially as and for the purpose described and illustrated in Figs. 1.
and 2 of the accompanying drawing.
2. The modified form of fixing the transparent strip of celluloid or the like in the
blade of the T-square or the like, substantially as and for the purpose described,
and illustrated in Figs. 3, 4, and 5 of the accompanying drawing.
3. The improvements in T-squares or similar drawing instruments, substantially
as described and illustrated in the accompanying drawing.
Dated this 29th day of March 1894.
HUGHES, SON & Co.,
38, Chancery Lane, London, Agents for Applicant.