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 clear plastic semicircular protractor is contained within an irregularly shaped piece of plastic that features a French curve at the top, two triangles (of 60° and 45°) on the sides, and a 5-1/2" scale along the bottom.
- The scale is divided to 16ths of an inch and is marked by single inches from 1" to 5". The protractor is divided to single degrees and marked by tens from 10° to 90° to 170° and from 170° to 90° to 10°. A semicircular slot separates the protractor from the French curve. Cut-out stencils for six circles range in diameter from 1/8" to 7/16". Also included are two slots for drawing angles of 30° and 45° and templates for an equilateral hexagon and two closed curves. On the curve the object is marked: SP [/] PROTRACTOR – FRENCH CURVE – TRIANGLES – RULER – CIRCLE GAUGES. Between the protractor and scale, the object is marked: MADE IN U.S.A.; 2; STERLING 544. The markings were stamped in black but are wearing off.
- Sterling Plastics was operated by George and Mary Staab in Mountainside, N. J., through the late 1960s. It was a division of Borden Chemical Company in the 1970s and 1980s, during which time this object was called the 7-IN-1 Protractor. For other products of Sterling Plastics, see slide rule 1988.0807.01 and adding machine MA*335327. James J. Williams gave this protractor to the Smithsonian.
- Reference: Toxic Substances Control Act: Trademarks and Product Names Reported in Conjunction with the Chemical Substance Initial Inventory (Washington, D.C.: United States Environmental Protection Agency, 1979), 90.
- Currently not on view
- date made
- ca 1975
- Sterling Plastics
- ID Number
- nonaccession number
- catalog number
- Data Source
- National Museum of American History, Kenneth E. Behring Center