A NEW OR IMPROVED COMBINATION DRAWING SQUARE
Year: 1879

page_text: LETTERS PATENT to Alfred Savage, of Great Dover Street, in the County of
Surrey, for the Invention of "A NEW OR IMPROVED COMBINATION DRAWING
SQUARE."
Sealed the 18th November 1879, and dated the 21st May 1879.
PROVISIONAL SPECIFICATION left by the said Alfred Savage at the Office
of the Commissioners of Patents on the 21st May 1879.
ALFRED SAVAGE, of Great Dover Street, in the County of Surrey. "A NEW OR
IMPROVED COMBINATION DRAWING SQUARE."
The
This Invention relates to a new or improved combination drawing square.
According to this Invention the blade of the square is attached to the head so
that it may be moved round on a centre fixed to the head, a thumb screw binding
the two tightly together in any required position. The angles are set out on the
head so that the blade may be immediately set at any required angle thereto.
blade is divided on one or both edges into inches, or parts, or any other measure
desired. Along the centre of the blade is a slot, along which travels a slide so adapted
that it may be fixed at any point desired, and will hold a pencil in its centre.
The thumb screw binding the blade and head is then slackened, and a curve may
be struck of a radius according to the point at which the slide and pencil have
been fixed. To so draw a curve or circle from any given point a hole is bored
through the pin on which the blade turns, down which a needle may be passed to
determine the exact centre. Instead of the slide and pencil holder a succession of
small holes may be drilled down the centre line of the blade. The blade may be
entirely removed from the head, and used as a rule or straight edge.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alfred Savage in the Great Seal Patent Office on the 21st November
1879.
ALFRED SAVAGE, of Great Dover Street,in the County of Surrey.
IMPROVED COMBINATION DRAWING SQUARE."
"
A NEW OR
This Invention relates to a new or improved combination drawing square.
And in order that the same may be clearly understood and readily carried into
effect I will proceed to describe it with the aid of the accompanying Drawings, in
which Fig. 1 is a plan, and Fig. 2 an edge view of one form of my Iuvention, and
Figs. 3, 4, and 5, views of another form thereof.
According to iny Invention the blade A (Figs. 1 and 2) is attached to the head B, so
that it may be moved round a centre C, a thumb screw D binding the blade and head
tightly together at any desired angle of the circle. The angles are set out on the
head B around the centre as in an ordinary protractor, so that the blade and head
may be readily set at any desired angle in relation to one another, or simply the
lines for "mitre" and "square" may be indicated as shown on the Drawing. The
blade has a metrical scale on one or both edges. Along the centre of the blade arc
a series of holes E at determined distances apart to be used for striking circles or sec-
tions of circles. For this purpose the point of a pencil is inserted in one of the holes
(according to the radius of the circle or section thereof desired); the thumb screw D
is slackened, and blade A with the pencil is moved around the centre C, and the
curve is thus struck. Or instead of said holes E a slot F extends along the
centre of the blade, as seen at Figs. 3 and 4. This slot is provided with a
slide G, having a pointer g, by which the desired position of the slide may be
determined. Through the slide passes a pencil holder g', having a shoulder bearing
against the underside of the blade and above a screw g², taken onto by a thumb
nut H, which, when screwed down binds both pencil holder and slide onto the blade.
Through nut H passes a set screw I for adjusting the lead in the holder, the holder
being split and retaining the lead by its elasticity. Slide, holder, nut, and set screw
are shown detached at Fig. 5.
The blade may be wholly detached from the head and used separately.
I claim as my Invention a new or improved combination drawing square, in which
the blade may be moved around a centre in the head, the blade being provided
with holes or a slot and slide for drawing circles or sections thereof, substantially as
herein before set forth and described and illustrated in the accompanying Drawings.
In witness whereof, I, the said Alfred Savage, have hereunto set my hand
and seal, this Twenty first day of November, One thousand eight hundred
and seventy-nine.
A. SAVAGE. (L.S.)