Triangular Chain Scale

This 12-inch triangular boxwood rule has indentations along each side. One side has scales divided to 1/10" (numbered by ones from 0 to 12) and 1/40" (numbered by twos from 0 to 48). This side is marked: U. S. ST'D. The second side has scales divided to 1/60" (numbered by twos from 0 to 72) and 1/30" (numbered by twos from 0 to 36). The third side has scales divided to 1/50" (numbered by twos from 0 to 60) and 1/20" (numbered by twos from 0 to 24). Initials are carved in one end of the rule: HW.
Unlike, for instance, 1981.0933.10, the numbers are engraved inside the indentations. W. & L. E. Gurley and the Eugene Dietzgen Company sold similar scales in the early 20th century for about one dollar.
William J. Ellenberger (1908–2008), who donated this object, studied electrical and mechanical engineering at The George Washington University between 1925 and 1934. He then worked for the Potomac Electric Power Company and the National Bureau of Standards. During World War II, he served in the U.S. Army Signal Corps. He was a civilian construction management engineer for the army from 1954 to 1968, when he became a private consultant.
References: Catalogue & Price List of Eugene Dietzgen Co., 7th ed. (Chicago, 1904), 160; W. & L. E. Gurley, A Manual of the Principal Instruments Used in American Engineering and Surveying, 46th ed. (Troy, N.Y., 1912), 405; Catalogue & Price List of Eugene Dietzgen Co., 12th ed. (Chicago, 1926), 168; "The GW Engineering Hall of Fame 2006 Inductees,"
Currently not on view
Object Name
scale, triangular
scale rule, triangular
date made
early 20th century
Physical Description
boxwood (overall material)
overall: 2 cm x 32 cm x 2 cm; 25/32 in x 12 19/32 in x 25/32 in
ID Number
catalog number
accession number
Drafting, Engineering
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Scale Rules
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
Gift of William J. Ellenberger
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