Alteneder 1666 Beam Compass

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
Theodore Alteneder and Sons
place made
United States: Pennsylvania, Philadelphia
Physical Description
metal (overall material)
steel (overall material)
lead (overall material)
overall: 40.9 cm x 7.5 cm x 1.3 cm; 16 3/32 in x 2 15/16 in x 1/2 in
ID Number
accession number
catalog number
Credit Line
Gift of Robert B. Condon
Drawing Instruments
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Dividers and Compasses
Data Source
National Museum of American History


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