Darling, Brown and Sharpe Triangular Scale for Draughtsmen

This nickel-plated steel instrument is crimped in the middle so that the scales along both edges are angled, giving the object the appearance of a triangle and bringing the scale closer to the draftsman's work. Both edges have scales dividing one inch into 48 parts and scales divided to one inch and numbered by ones from 0 to 11. One edge is marked: D.B.&S. PROV. R.I. Pt. Aug. 3. 80.
Darling, Brown & Sharpe of Providence, R.I., marketed this rule to draftsmen and architects for making scale drawings in which 1" = 1'. For more information on the history of this rule, see 1977.0460.06, which is the same instrument with a scale of 3" = 1'. For another drafting tool designed by Samuel Darling, see 1990.0317.02. This example was owned by the renowned American designer of steam engines, Erasmus Darwin Leavitt Jr. (1836–1916), and donated by his granddaughter, Margaret van D. Rice.
Currently not on view
Object Name
scale rule
rule, triangular
date made
Darling, Brown & Sharpe
Physical Description
steel (overall material)
nickel (overall material)
overall: 1.2 cm x 31.2 cm x 2.3 cm; 15/32 in x 12 9/32 in x 29/32 in
place made
United States: Rhode Island, Providence
ID Number
accession number
catalog 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


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