Geometrical instruments – Straightedge type
Patent
1987-07-22
1988-12-20
Haroian, Harry N.
Geometrical instruments
Straightedge type
33565, B43L 1302
Patent
active
047917334
ABSTRACT:
A student's multi-function protractor for conveniently drawing different geometric figures including a transparent middle plate which fits on the retainment space between an upper base and a lower base. The middle plate is rotatable in the retainment space. The circumferential edge with the middle plate of the upper base has a 360 degree scale. In addition, the middle plate has a plurality of parallel grooves which are scattered on one side from the central point for providing direct drawings. By accompanied with the grooves, scales and the indication elements on the middle plate, the protractor of this invention is used to easily draw different geometric figures.
REFERENCES:
patent: D165849 (1952-02-01), Jordan
patent: 224811 (1980-02-01), Wilson
patent: 649339 (1900-04-01), Thompson
patent: 2004951 (1935-06-01), Jensen
patent: 2190071 (1940-02-01), Keppers
patent: 2624117 (1953-01-01), Paci
patent: 3460261 (1969-08-01), Frey
patent: 3925899 (1975-12-01), Hesse et al.
patent: 4625425 (1986-12-01), Senno et al.
Pan Shih C.
Tseng Ching P.
Haroian Harry N.
Huey Bao Co., Ltd.
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