J. L. Hammett Co. Open Triangle

The interior of this 20-1/2" 30°-60°-90° fiberboard triangle is divided into two open triangles that are approximately 45°-60°-75° and 30°-45°-105°. The hypotenuse is marked: J. L. HAMMETT CO. (/) CAMBRIDGE, MASS. (/) NEWARK, N.J. The instrument is sized for blackboard use. It has no markings for measuring angles or lengths.
John Hammett began selling erasers and slating paint for chalkboards in Rhode Island in 1863, moving to Boston in 1865. In 1890 new owners expanded the firm into all forms of paper school supplies. Now called the J. L. Hammett Co., the firm opened factories in New York, New Jersey, and Massachusetts after 1895; moved its headquarters to Braintree, Mass., in 1967; and operated over 50 retail stores from 1974 to 2005. Neither this drawing instrument nor MA*304722.44 appear in Hammett catalogs published between about 1870 and 1903. The Department of Mathematics at Brown University gave this object to the Museum in 1973.
References: Bill Lane, "School Supplier J. L. Hammett to Close Stores," Boston Business Journal, January 4, 2005, http://www.bizjournals.com/boston/stories/2005/01/03/daily12.html; "J. L. Hammett Company," The Play and Playground Encyclopedia, http://www.pgpedia.com/j/jl-hammett-company.
Currently not on view
date made
J. L. Hammett Co.
place made
United States
Physical Description
tempered fiberboard (overall material)
overall: 61 cm x 26.8 cm x .3 cm; 24 1/32 in x 10 9/16 in x 1/8 in
ID Number
catalog number
accession number
Credit Line
Gift of Brown University Department of Mathematics
Drawing Instruments
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Squares and Triangles
Data Source
National Museum of American History, Kenneth E. Behring Center


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