Squares & TrianglesTriangles
The triangles in the mathematics collections illustrate the products sold by leading American makers of drawing instruments, including Darling, Brown & Sharpe of Providence, R.I.; and Keuffel & Esser of New York City. An American inventor, LeRoy J. Leishman, devised the Arcascope triangle and combination instrument. The objects on this page also show a transition from triangles made from steel, wood, and rubber to triangles made from plastic. The change in materials in the early 20th century has created a problem for preserving these instruments, as celluloid-based plastics are chemically unstable. Several of these objects are deteriorating despite efforts to store them in a controlled environment.
"Squares & Triangles - Triangles" showing 1 items.
- This 4" 45°-45°-90° triangle is made of hard black rubber. One edge is marked: KEUFFEL & ESSER (/) N.Y.; TRADE MARK (below the K&E eagle logo). The hypotenuse is marked: 1/2 PITCH. At least as early as 1880, K&E sold this object as part of a set of six hard rubber triangles with various angle sizes. The triangles were used for depicting roof pitches in architectural drawings. In 1890 and 1892 the set sold for $3.00 as model number 1805. By 1906 the set was made of transparent xylonite (plastic).
- The triangle was found in the NMAH Physical Sciences collections in 1979 with objects that suggest an association with Cleveland Abbe (1838–1916), an American engineer, astronomer, and meteorologist who worked for the U.S. Weather Service from 1871 until shortly before his death.
- References: Catalogue of Keuffel & Esser Co., 13th ed. (New York, 1880), 131; Catalogue of Keuffel & Esser Co., 21st ed. (New York, 1890), 135; Catalogue of Keuffel & Esser Co., 23rd ed. (New York, 1892), 135; Catalogue of Keuffel & Esser Co., 32nd ed. (New York, 1906), 223; accession file.
- Currently not on view
- date made
- Keuffel & Esser Co.
- ID Number
- catalog number
- accession number
- Data Source
- National Museum of American History, Kenneth E. Behring Center