Geometrical instrument
United States Patent 2631376
US Patent References:
/0744963.html
- - 0744963

/0895258.html
- - 0895258

Line-spacing device
- - 1383759

Ruling apparatus for characters
- - 1692149

Drafting instrument
- - 1704540


Inventors:
Leo, Callahan Ezra
Publication Date:
03/17/1953
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Assignee:
Leo, Callahan Ezra
Primary Class:
33/424
Other Classes:
33/27.030
International Classes:
B43L7/00
US Patent References:
1800452Translucent edge for instruments
1808705Combination compass protractor and ruler
1944812Protractor
2142765Drafting tool
2154753Drafting instrument
2337315Combined square and compass
2428699Drafting instrument
2438337Combination rule and compass
Foreign References:
DE514930C
GB548232A