Arcascope Triangle and Combination Instrument

Arcascope Triangle and Combination Instrument

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This 8" transparent plastic instrument consists of a 30°-60°-90° triangle with an 8" scale along the long leg, divided to 1/8" for four inches and to 1/16" for four inches; a 10 cm scale along the short leg, divided to millimeters; and a protractor cut out from the interior, divided to single degrees and marked by tens in both directions from 10 to 180. Between the protractor and centimeter scale are two sets of angled lines, each between two X's and the letters A and B. These lines are used in conjunction with two unevenly divided scales on the hypotenuse of the triangle to determine the angle of an arc and the length of the diameter from the arc of a circle. The first scale is numbered by ones from 6 to 90; the second is numbered by ones from 10 to 60 and then by twos from 60 to 100.
The device is marked: THE ARCASCOPE (/) PATENTED MAY 2, 1916 (/) OTHER PATENTS PENDING (/) COPYRIGHT 1917 (/) L. J. LEISHMAN CO. (/) OGDEN, UTAH. It was donated to the Museum by the Department of Physics at Kenyon College in 1982.
LeRoy James Leishman (1896–1974) was still in high school when he invented this instrument and formed a company to produce and distribute it. He registered a copyright for the name "Arcascope" on October 13, 1913; applied for a patent on October 21, 1914, although the submitted drawing was very different from the final instrument; and submitted two copies of the copyrighted instrument on October 18, 1915. Leishman claimed that his device, which sold for 85¢ in 1919 and 50¢ in the 1920s, was popular with schools for solving problems in trigonometry, geometry, and drafting. He produced eight inventions by the time he was 20 years old and moved to Los Angeles around 1920. In the 1920s and 1930s he obtained several patents related to television, and in the 1940s and 1950s he developed devices that applied television principles to medical technology.
References: "Ogden Invention is Being Placed on the Market," The Ogden Standard (October 21, 1914), 7; Library of Congress, Catalogue of Copyright Entries, Part 4: Works of Art, n.s., vol. 9, no. 1 (Washington, D.C.: Government Printing Office, 1914), 525; "Ogden Inventor Forms Company," The Ogden Standard (September 28, 1915), 8; LeRoy J. Leishman, "Measuring Instrument" (U.S. Patent 1,181,900 issued May 2, 1916); W. E. Zuppann, "Pictures Sent by Wireless," Illustrated World 26, no. 5 (January 1917): 678–680; "LeRoy James Leishman Papers," Harold B. Lee Library, Brigham Young University,
Currently not on view
Object Name
date made
after 1917
Leishman, LeRoy J.
place made
United States: Utah, Ogden
Physical Description
plastic (overall material)
overall: 24 cm x 10.5 cm x.1 cm; 9 7/16 in x 4 1/8 in x 1/32 in
ID Number
catalog number
accession number
Credit Line
Gift of Kenyon College Department of Physics
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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