Circular Protractor

Circular Protractor

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This circular brass protractor is graduated by degrees and bears eight sets of markings by fives from 5 to 45. Each 45-degree section is labeled underneath the numbers: M; an inverted V over a cross; G; an X superimposed on a cross; S; O; A; P. These letters and symbols do not correspond to any standard sets of astronomical, astrological, or mathematical symbols. Two crosspieces on the interior of the protractor are marked with the Latin alphabet: ABCDEFGHIKLM; NOPQRSTVXYZG. It is not known what the final G signifies. A scale above the alphabet is divided into four increments per letter. A brass limb is affixed to the center of the protractor. The limb is divided and marked by tens from 10 to 90. Each division is approximately 3/8" wide.
The instrument is decorated with scrolling, fleurs-de-lis, and a flower at the center of the limb that resembles a pansy. The craftsmanship is crude on the whole, with the angle divisions in particular appearing to be drawn free-hand rather than stamped. The instrument also may have been cut by hand from a sheet of brass. If this protractor is authentic, it likely dates to around 1700.
The Smithsonian purchased this instrument in 1959 from a dealer in antiques, Maurice van Geuns (1905–2000) of New York City. Van Geuns grew up in Groningen in the Netherlands. He spent two years in France in the early 1940s and then enlisted in the U.S. Army in 1943 and served five years.
Reference: "Je woont in New York en kunt je geboortestad niet vergeten (16 Dec.)," Voices from Holland: A Bilingual Quarterly Update of News from the Netherlands (Winter 1997-1998): 6,
Currently not on view
Object Name
Physical Description
brass (overall material)
overall:.3 cm x 16 cm x 24.5 cm; 1/8 in x 6 5/16 in x 9 21/32 in
ID Number
accession number
catalog number
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Medicine and Science: Mathematics
Science & Mathematics
Data Source
National Museum of American History
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