Japanese L-Square with Calipers

This 8" brass T-square is shaped like an L and has a second short leg attached to a slide on the long leg. On one side, the outer edge of the square is divided into units of 1-3/16" (3 cm), roughly equivalent to the sun, a traditional Japanese unit of length. Each unit is subdivided into 20 parts. The units on the long leg are marked with an O, with three circles marking the fifth unit. The inner edge of the long leg has a 15-centimeter scale, divided to millimeters. The back of the square has a diagonal scale. Compare to MA*261296.
In 1876 the Japanese Empire Department of Education exhibited many instruments at the Centennial International Exhibition, a World’s Fair held in Philadelphia. After the exhibition, John Eaton, the U.S. Commissioner of Education, arranged for the transfer of Japan's entire exhibit to the Bureau of Education (then part of the Department of the Interior) for a planned museum. The museum closed in 1906, and much of the collection, including this object, was transferred to the Smithsonian in 1910.
References: Japan. Department of Education, An Outline History of Japanese Education: Prepared for the Philadelphia International Exhibition, 1876 (New York: D. Appleton, 1876), 121–122, 191–202; U.S. Centennial Commission, International Exhibition, 1876. Reports and Awards, ed. Francis A. Walker (Washington, D.C.: Government Printing Office, 1880), viii:143, 335; U.S. Bureau of Education, Annual Report of the Commissioner (1876), ccxi–ccxii.
Currently not on view
Object Name
set square
date made
before 1876
Physical Description
brass (overall material)
overall: 21 cm x 11.5 cm x .6 cm; 8 9/32 in x 4 17/32 in x 1/4 in
place made
ID Number
accession number
catalog 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
Transfer from Bureau of Education, Department of the Interior
Additional Media

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