Keuffel & Esser 1802 12" Drafting Triangle

This 12" 30°-60°-90° hard rubber triangle has a small triangular opening in the interior. On one side, the short side is marked: KEUFFEL & ESSER CO. (/) NEW YORK (/) AND (/) CHICAGO; 12. K&E's eagle trademark is to the right of the number 12, above the word TRADEMARK. On the other side, the short side is marked: S. T. [in script] (/) A. R. O. That side also has three concentric circles near the hypotenuse of the opening.
By 1890 Keuffel & Esser was making the shape of the hole in its hard rubber triangles triangular instead of circular. The 12-inch size of model number 1802 sold for 90¢ from 1890 to 1909 and for 75¢ in 1913. By 1921 the firm no longer offered hard rubber triangles, perhaps due to shortages of the material during World War I as well as improvements in the manufacture of plastic. The mark suggests that the object's date can be narrowed to 1892–1894, since that was the period when Chicago was K&E's only branch office.
References: Catalogue of Keuffel & Esser Co., 21st ed. (New York, 1890), 135; Catalogue of Keuffel & Esser Co., 33rd ed. (New York, 1909), 202; Catalogue of Keuffel & Esser Co., 34th ed. (New York, 1913), 200; Hoboken Historical Museum, "Triangle: pearwood framed drawing, [group of] 3,";id=5D8ED8D1-A698-42D7-AA97-396737757553;type=101.
Currently not on view
date made
ca 1890-1918
place made
United States: New York, New York
Physical Description
rubber (overall material)
overall: 7.5 cm x 30.5 cm x .2 cm; 2 15/16 in x 12 in x 3/32 in
ID Number
catalog number
accession number
Credit Line
Gift of Danny Morris
Drawing Instruments
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Squares and Triangles
Data Source
National Museum of American History


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