IMPROVEMENTS IN ANGLES, T SQUARES, STRAIGHT EDGES, PARALLEL RULES, AND OTHER SIMILAR INSTRU- MENTS EMPLOYED IN DRAWING
Year: 1854

page_text: LETTERS PATENT to Charles Thompson Guthrie, of New Bond Street, in
the County of Middlesex, for the Invention of "IMPROVEMENTS IN ANGLES,
T SQUARES, STRAIGHT EDGES, PARALLEL RULES, AND OTHER SIMILAR INSTRU-
MENTS EMPLOYED IN DRAWING."
Sealed the 1st June 1855, and dated the 11th December 1854.
PROVISIONAL SPECIFICATION left by the said Charles Thompson Guthrie
at the Office of the Commissioners of Patents, with his Petition, on the
11th December 1854.
I, CHARLES THOMPSON GUTHRIE, of New Bond Street, in the County of
Middlesex, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN ANGLES, T SQUARES, STRAIGHT EDGES, PARALLEL RULES, AND OTHER
SIMILAR INSTRUMENTS EMPLOYED IN DRAWING," to be as follows:-
Heretofore such instruments have for the most part been made of wood and
other opaque materials, which are very liable to retain dirt or other matters
calculated to soil the paper or other substance used to draw upon, as also to
become warped and otherwise distorted.
And my improvements consist in manufacturing such instruments from glass,
preferring for that purpose the best plate glass, ground or otherwise made true
to the desired form, as I have discovered that, by the employment of such
material in the manufacture of such instruments, dirt or other matters which
accumulate thereon may readily be removed, and the paper or other substance

page_text: being drawn on thereby kept much cleaner than when those instruments are
made of the materials heretofore used, whilst they are at the same time not
subject to distortion; and their being transparent, offers also considerable
facilities in drawing, by enabling the user to see lines which for the time may
be covered by one of such instruments.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Charles Thompson Guthrie in the Great Seal Patent Office
on the 9th June 1855.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
THOMPSON GUTHRIE, of New Bond Street, in the County of Middlesex, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eleventh day of December, in the year of our Lord
One thousand eight hundred and fifty-four, in the eighteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Charles Thompson Guthrie, Her special licence that I, the said Charles
Thompson Guthrie, my executors, administrators, and assigns, or such others
as I, the said Charles Thompson Guthrie, my executors, administrators, and
assigns, should at any time agree with, and no others, from time to time and
at all times thereafter during the term therein expressed, should and lawfully
might make, use, exercise, and vend, within the United Kingdom of Great
Britain and Ireland, the Channel Islands, and Isle of Man, an Invention for
"IMPROVEMENTS IN ANGLES, T SQUARES, STRAIGHT EDGES, PARALLEL RULES, AND
OTHER SIMILAR INSTRUMENTS EMPLOYED IN DRAWING," upon the condition (amongst
others) that I, the said Charles Thompson Guthrie, by an instrument in
writing under my hand and seal, should particularly describe and ascertain the
nature of the said Invention, and in what manner the same was to be per-
formed, and cause the same to be filed in the Great Seal Patent Office within
six calendar months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said Charles Thompson Guthrie, do hereby
declare the nature of the said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by the
following statement thereof (that is to say):
Heretofore such instruments have for the most part been made of wood or
other opaque materials, which are very liable to retain dirt or other matters

page_text: rollers c, c, would be affixed to the rod c', which turns in the glass tube d,
except at the ends, where I prefer that it be supported in the metal bearings
e, e, which are secured to the glass plate by cement and screws, as shown, and
the surface of the tube d in contact with the plate f I affix to that plate by a
solution of isinglass, white lead, or other suitable cement. Figure 12 shows
a sector, formed according to my improvements, of glass, with the graduations
cut in it, and I prefer that those graduations be cut on the under side, or that
next the paper or other matter to be drawn on. Other drawing instruments,
constructed according to my improvements, of glass, may also be graduated,
as may be desired. In like manner may other instruments employed in
drawing be formed of glass, by which, as already stated, cleanliness with
convenience will be obtained.
Having thus described the nature of my said Invention, I would have it
understood that I do not confine myself to the precise details shown and
described; but what I do claim is, for forming angles, T squares, straight
edges, parallel rules, and other similar instruments employed in drawing, of
glass.
In witness whereof, I, the said Charles Thompson Guthrie, have hereunto
set my hand and seal, this Ninth day of June, in the year of our Lord
One thousand eight hundred and fifty-five.
Witness,
B. J. B. MILLS,
73, Chancery Lane.
C. T. GUTHRIE. (L.S.)