Dietzgen Limb Protractor

This German silver protractor is in the shape of a quarter-circle. It is divided by half-degrees and marked by tens from 0° to 90°. Flat bars extend on both sides of the protractor. A movable arm extends from the vertex of the quadrant. A tab is cut out from this limb to permit reading the angle markings. The arm is secured by a brass thumbscrew that is near the origin point for the angle markings. The protractor is noticeably rusted and tarnished.
There is a signature on the bottom edge: E. D. – Co. (/) NEW YORK & CHICAGO. Around 1880, Eugene Dietzgen emigrated from Germany and became a sales distributor for Keuffel & Esser in New York. In 1885, he began to sell mathematical instruments on his own in Chicago. In 1893, his firm started manufacturing instruments under the name Eugene Dietzgen Company. However, this protractor was not advertised in Dietzgen catalogs that were published between 1902 and 1947.
Leslie Leland Locke (1875–1943) originally owned this protractor. A student at Grove City College, he earned a bachelor's degree in 1896 and a master's degree in 1900. He taught mathematics at Michigan State College, Adelphi College, and Brooklyn College and its Technical High School. He was interested in Peruvian quipu, mysterious and ancient systems of knotted strings used to store and communicate information and data. He donated his collection of early calculating machines to the Smithsonian and his early American textbooks to the University of Michigan.
Reference: Louis C. Karpinski, "Leslie Leland Locke," Science n.s., 98, no. 2543 (24 September 1943): 274–275.
Currently not on view
Object Name
date made
ca 1900
Eugene Dietzgen Company
Physical Description
german silver (overall material)
overall: 1.5 cm x 17.5 cm x 17.7 cm; 19/32 in x 6 7/8 in x 6 31/32 in
Place Made
United States: New York, New York
ID Number
accession number
catalog number
Science & Mathematics
See more items in
Medicine and Science: Mathematics
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
Gift of Grove City College
Additional Media

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