IMPROVEMENTS IN TRY SQUARES
Year: 1879

page_text: LETTERS PATENT to Herbert John Haddan, of the Firm of Herbert and Com-
pany, Solicitors of Patents, of 67, Strand, in the City of Westminster, Civil
Engineer, for the Invention of "IMPROVEMENTS IN TRY SQUARES." A com-
munication from abroad by Laroy Sunderland Starrett, of the State of
Massachusetts, United States of America.
Sealed the 15th July 1879, and dated the 16th May 1879.
COMPLETE SPECIFICATION filed by the said Herbert John Haddan at the
Office of the Commissioners of Patents on the 16th May 1879.
HERBERT JOHN HADDAN, of the Firm of Herbert and Company, Solicitors of
Patents, of 67, Strand, in the City of Westminster, Civil Engineer. " IMPROVE-
MENTS IN TRY SQUARES." A communication from abroad by Laroy Sunderland
Starrett, of the State of Massachusetts, United States of America.
The nature of my Invention is duly set forth in the claim or claims hereinafter
presented. In the Drawings, Figure 1 is a side elevation, Figure 2 an end view,
and Figure 3 a transverse section of a try square of my improved kind. A denotes
a graduated steel rule or bar, having exended through it lengthwise on one side of
it a long groove a, which is rectangular in its transverse section. This bar enters
and slides in a recess b formed in the foot or lower part of a stock B, one edge c of
which is at a right angle to its lower edge d, while the other e is at an angle of
forty five degrees with such lower edge. Within a socket and opening into the
recess, and made in a boss farranged in the stock, as represented, there is a clamp
hook C formed to engage with the groove of the bar A, and provided with a nut D
that is secured on the shank of clamp, and is counterbored, and has within it a
helical spring g to bear on the top of the base, and to serve when the nut is loosed
to draw the clamp upward so as not only to prevent the bar from falling out of
place in the stock, but dirt or extraneous matters from working between the bar
and the top of the recess in which such bar is placed, and thereby throw the bar
out of its right angular position to the edge c of the stock. A pin inserted in the
base and projected into a hole i in the shank of the clamp prevents the clamp from
revolving in the base. The foot of the clamp extends into the recess b and the
groove of the bar A. Furthermore, there is within the stock and parallel to its

page_text: edge ca spirit level E, which is protected by an arch extending lengthwise over
it, as shown. The stock is also provided with a socket to receive a stylus or
scratch pin F, which by a friction spring m is prevented from accidentally dropping
out of the socket. The rule or bar besides having at its opposite edges divisions
or lines indicating inches and equal parts thereof has made through it several
holes o half an inch or other suitable distances apart from each other, from centre
to centre, such being of proper diameter to allow the point of the awl or scratch
pin to be extended into and through it far enough to make gauge marks when it
may be desirable to use the instrument for laying out work, or mortices, or tenons.
One or more holes p near the end of the bar may be countersunk to admit of the
point of a lead pencil being introduced through either, and used instead of the
scratch pin for making gauge marks. The working edges c, e, of the stock are
placed far enough apart for the bottom upper edge of the bar recess to be long
enough to afford a suitable bearing for the bar, and also to admit of the boss being
made between them, whereby the clamp is not only covered and protected on all
sides, and shielded from dust or extraneous matters, but is prevented from acciden-
tally slipping sideways out of the groove in the bar. The instrument made as
shown can be used to excellent advantage by draughtsmen or joiners in line
drawing, or laying out lines at right angles, or at angles of forty five degrees to
each other, all of which will be readily comprehended by persons skilled in the use
of similar instruments. I do not claim broadly a slide bar and a stock therefor,
having edges arranged at an angle of forty five degrees to each other, one of them
being at a right angle to the bar, but what I claim as my Invention is as follows:-
1. The stock provided with the bar receiving recess and base, as described, and
with the clamp arranged in such recess and base, substantially as set forth. 2. The
combination with the hooked clamp provided with a screw on its shank, and
arranged with the bar and stock, as described, of the counterbored nut, and the
helical spring placed therein, and to act against the top of the boss, as and for the
purposes set forth. 3. The stock provided with the sheath to receive the scratch
pin, and a friction spring to keep such pin in place, and also with the slide bar
arranged within, and applied to such stock, as set forth. 4. The stock provided
with the spirit level and its guard arch, and the scratch pin sheath arranged in
such stock, as set forth, in combination with the slide bar and its clamping devices,
applied to the stock as represented. 5. The slide bar made with divisions and
scratch holes, arranged substantially as explained. 6. The combination with the
slide bar and the stock of a spring so applied as to force the slide bar up to the top
of its receiving recess in the stock.
In witness whereof, I, the said Herbert John Haddan, have hereunto set my
hand and seal, this Sixteenth day of May, A.D. 1879.