Geometrical Instrument Page: 2 of 3
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UNITED STATES PATENT OFFICE
ANDREW ELLIOTT ANDERSON, OF BROWNSVILLE, TEXAS.
GEOMETRICAL INSTRUMENT.Specification of Letters Patent.
Patented Mar. 26, 1918.
Application filed December 26, 1916. Serial No. 18,812.
To all whomt it may concern:
Be it known that I, A-N DREW ELLIOTT
ANDERsox. a citizen of the United States
of America, residing at Brownsville, in the
5 county of Cameron and State of Texas, have
invented new and useful Improvements in
Geometrical Instruments, of which the fol-
lowing is a specification.
The present invention relates to im-
1o provements in geometrical instruments of
the straight-edge type and involves the use
of pivoted blades, as in a protractor, for lay-:
ing out, measuring or protracting angles,
etc.
15 The invention is designed to provide an
instrument of this character having straight
edges movable in the same plane and in such
a manner that any angle between zero and
1800 may be laid out, and either of which
20 straight edges may be made free and un-
obstructed from end to end in order that
the drawing of a line from end to end of the
straight edge is made possible, and also in
order that the measuring or scaling of a line
25 by any suitable means found desirable is
facilitated.
The invention consists in certain novel
combinations and arrangements of parts as
will be hereinafter described and claimed.
30 Figure 1 is a top plan view of my com-
plete instrument.
Fig. 2 is a plan view of one of the blades
detached.
Fig. 3 is a view-in elevation showing one
35 blade in position, the base ring being broken
away and the second blade omitted for con-
venience of illustration.
Fig. 4 is a detail plan view of a vernier
plate.
40 Fig. 5 is a detail plan view of a clamp
plate.
Fig. 6 is a sectional view, enlarged, on line
a-a Fig. 1, the section line also being indi-
cated in the same manner in Figs. 2, 4,
45 and 5.
In the'- preferred embodiment of my in-
vention as illustrated in my drawings the
instrument includes a pair of blades as 1
and 2, of metal or other suitable material,
50 and as arranged and combined with the
other elements of the instrument each blade
is fashioned with a pair of parallel straight
edges, the inner edges of the blades being
indicated by the respective numerals 3 and
55 4 and the outer edges of the blades being in-
dicated by the numerals 5 and 6. Theblades 1 and 2 are movable in the same plane
and adapted to swing about the same center,
with the inner ends of the inner straight
edges always in contact as at the point or
corner 7 in Fig. 1, and the movement of the
blades permits them to be turned or swung
from a point of coincidence with the two
edges. 3 and 4 in parallelism and in contact,
to measure or lay out between them any
angles up to an angle of 1800.
The two blades are combined with the
base ring 8 which is a graduated, circular,
open center plate, preferably of metal, and
the two blades may be swung or revolved
about the ring and held in adjusted position
by means of a set of plates 9 and 10 and 9'
and 10' respectively. The base plates 9 and
9' are each provided with a circular groove
12 coincident with the base ring 8, and as
the base plates are provided with a vernier,
as shown I will hereinafter call them the
vernier plates or grooved vernier plates to
distinguish them from their complementary
plates of resilient metal 10 and 10' which
are the clamp plates for holding the blades
in adjusted position. The vernier plates
and the clamp plates are secured to the
blades by means of screws 11 passing
through both plates and the respective
blades, and each pair of plates is provided
with a fixed screw bar as 13 and 13' fixed
in the respective blades and passing through
openings or perforations in the pairs of
plates. Each of the screw bars has a clamp
nut as 14, -14' threaded thereon and the nuts
bear upon the upper face of the clamp
plates, so that by properly turning these
nuts it will readily be seen that the ring 8
may be clamped or clasped and held between
the pairs of plates, thus rigidly holding the
blades with relation to the base ring 8.
Each of the clamp plates 10 and 10' is fash-
ioned with a notch or recess as 15 and 15'
and these notches are adapted to engage the
respective pins 16 and 16' in order to limit
the movement of the blades on the base ring.
When the two inner ruling edges are fitted
together it will be seen that the pins will be
engaged in the notches and in this position
the verniers on the plates 9 and 9' are auto-
matically set at zero or first graduations
from the ends of the base ring, the clamp
plates being cut away in order that the
verniers on the plates and the scale on the
ring may be read with facility.
It will readily be seen that both blades1,260,292.
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Reference the current page of this Patent.
Anderson, Andrew E. Geometrical Instrument, patent, March 26, 1918; [Washington D.C.]. (https://texashistory.unt.edu/ark:/67531/metapth1257026/m1/2/?q=%22%22~1: accessed June 21, 2024), University of North Texas Libraries, The Portal to Texas History, https://texashistory.unt.edu.; crediting UNT Libraries Government Documents Department.