Japanese L-Square

Description
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—including this object—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 was transferred to the Smithsonian in 1910.
On one side, this 18-1/2" L-shaped brass instrument is divided along the outside of its short leg into 7.5 units of 1-3/16" (3 cm). Each unit is thus roughly equivalent to the sun, a traditional Japanese unit of length that is 1/10 of a shaku, a "foot" measure. The units are subdivided into 10 parts. The fifth unit is marked with an arrangement of five dots.
The outer edge of the long leg is divided into ten units of 1-3/4" (4.3 cm). Each unit is subdivided into tenths. From the right, the fifth and tenth units are marked with an arrangement of five dots. The other units are marked with single dots. A single dot also marks the 0.9 points. Groups of three dots mark the 3.55 and 7.05 points, and another group of three dots marks a point to the left of the divisions on the scale.
The inner edge of the long leg is divided from left to right into five units of 1-13/16" (4.5 cm) and five sun. The larger units are marked with Japanese characters. The sun are subdivided into tenths and marked with single dots, except for the fifth unit, which is marked with five dots.
On the other side, the outer edges of both legs are divided into sun subdivided into tenths. The midpoint of each unit is marked with three dots. The fifth, tenth, and fifteenth units from the vertex are marked with five dots. The instrument was designed for measuring lengths, drawing right angles, and determining whether two lines are perpendicular to one another.
Other educational mathematical objects exhibited by Japan in 1876 include MA*261283, MA*261284, MA*261285, MA*261286, MA*261287, MA*261289, MA*261291, MA*261292, MA*261293, MA*261294, MA*261298, MA*261299, MA*261301, MA*261302, MA*261305, MA*261306, and MA*261313.
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.
Location
Currently not on view
Object Name
set square
L-square
date made
before 1876
Physical Description
brass (overall material)
Measurements
overall: 47.3 cm x 24.2 cm x .4 cm; 18 5/8 in x 9 17/32 in x 5/32 in
place made
Japan
ID Number
MA*261295
accession number
51116
catalog number
261295
subject
Squares and Triangles
Science & Mathematics
Mathematics
Education
Engineering
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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