Dividers & CompassesBeam Compasses
Mechanical and architectural drawings have sometimes required circles with diameters of several feet instead of the several inches possible with a standard drawing compass. A beam compass was usually sold with just the points, which the user attached to the ends of a metal rod or wooden slat the length of the desired radius of the circle. One end was held in place, and the other end was pivoted around that end, maintaining contact with the paper. The patent model in the collection is a beam compass.
"Dividers & Compasses - Beam Compasses" showing 1 items.
- This instrument has two very tarnished flat metal bars, each 22 cm long, with tapered ends that interlock to make a beam of 40.9 cm. The two steel sliding trammels resemble pencils and are marked: T.A. & SONS. The longer trammel has a needle point, and the shorter has a pencil point. The shorter trammel has a cam wheel that allows adjustment up to 3/16". Spring tension in both trammels may be adjusted by turning a knurled nut.
- John Wesley Oehrli (1903–1969), an engineer and inventor who lived in State College, Pa., applied for a patent on this beam compass in 1944. He moved to Southern California by 1953, where he worked for McCulloch Motors Corporation, and received a total of 11 patents, mainly for chain saws and planetary drives in internal combustion engines. Theodore Alteneder & Sons sold the "improved tubular beam compass" as model number 1666 from 1945 through at least 1952 for $16.50. This object originally would have had a case.
- References: John W. Oehrli, "Beam Compass" (U.S. Patent 2,385,723 issued September 25, 1945); Insert dated 1945, Alteneder Drawing Instruments (Philadelphia, 1942); Alteneder Drawing Instruments (Philadelphia, 1952), 16.
- Currently not on view
- date made
- 1945-ca 1952
- Theo Alteneder & Sons
- ID Number
- accession number
- catalog number
- Data Source
- National Museum of American History, Kenneth E. Behring Center