Darling, Brown & Sharpe Drafting Triangle

In the early 19th century, draftsmen began to use triangles in combination with T-squares to draw vertical and diagonal lines. This steel 30°-60°-90° triangle is 14" tall. A hole near the 30° angle is for hanging. The instrument is marked: D. B. & S. Prov. R. I. (/) E. D. LEAVITT. Compare to 1977.0460.09 and 1977.0460.10.
D. B. & S. is the mark for Darling, Brown & Sharpe of Providence, R.I. Samuel Darling, a machinist who invented numerous drafting instruments, partnered with Joseph R. Brown and Lucian Sharpe between 1866 and 1892. For more on the history of Darling, Brown & Sharpe, see 1977.0460.01, 1977.0460.05, and 1977.0460.06. This object was not advertised in company catalogs published in 1868 and 1887.
Erasmus Darwin Leavitt Jr. (1836–1916), the renowned American mechanical engineer and designer of steam engines, owned this triangle. It was donated to the Smithsonian by his granddaughter, Margaret Van Daell Rice (1904–1979).
References: Maya Hambly, Drawing Instruments, 1580–1980 (London: Sotheby's Publications, 1988), 105; Bureau of Naval Personnel, Basic Hand Tool Skills (Washington, D.C.: Government Printing Office, 1954), 51; Kenneth L. Cope, intro., A Brown & Sharpe Catalogue Collection, 1868 to 1899 (Mendham, N.J.: The Astragal Press, 1997); Henry Dexter Sharpe, A Measure of Perfection: The History of Brown & Sharpe (North Kingston, R.I.: Brown & Sharpe, 1949), http://www.roseantiquetools.com/id44.html.
Currently not on view
Object Name
date made
Darling, Brown and Sharpe
Physical Description
steel (overall material)
overall: 20.2 cm x 35.3 cm x .2 cm; 7 15/16 in x 13 29/32 in x 3/32 in
place made
United States: Rhode Island, Providence
ID Number
catalog number
accession number
Squares and Triangles
Science & Mathematics
Drafting, Engineering
Drawing Instruments
See more items in
Medicine and Science: Mathematics
Squares and Triangles
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
Gift of Margaret van D. Rice

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