Felsenthal FAE-6 Set Square/Coordinate Scale

Description:

On one side, this 4-3/8" white plastic L-shaped square has scales along its inner edge for reducing yards to the representative fraction (R.F.) of 1:20,000, divided to twenties and numbered by 500s from 0 to 1,000. Scales along its outer edge are for reducing yards to R.F. 1:62,500, divided to hundreds and numbered by thousands from 1,000 to 6,000. The end of one leg is marked: U.S.

The other side has scales along its inner edge for reducing meters to R.F. 1:25,000, divided to twenties and numbered by 500s from 0 to 1,500. Scales along its outer edge are for reducing meters to R.F. 1:50,000, divided to fifties and numbered by thousands from 1,000 to 5,000. The end of one leg is marked: U.S. The device, also known as a "coordinate scale," was used by soldiers to compare measurements to notations on a chart in order to aim weapons. Compare to 1977.1141.16. This example was also received with a duplicate square, but the second square was broken and discarded.

According to the accession file, this instrument was made for the U.S. Army by Felsenthal Instrument Company in 1945 as model number FAE-6. The company was the leading supplier of mathematical instruments to the U.S. Army Air Force and the U.S. Navy Bureau of Aeronautics, particularly during World War II (when the firm was known as G. Felsenthal & Sons). After the company ceased operations in approximately 1976, it provided a large sample of its products to the Smithsonian. The lack of any form of the firm's name on this instrument suggests it may actually have been made in the 1960s. For company history, see 1977.1141.02.

Date Made: ca 1945

Maker: Felsenthal Instrument Co.

Location: Currently not on view

Subject: MathematicsArtillery

Subject:

See more items in: Medicine and Science: Mathematics, Squares and Triangles, Metric System, Science & Mathematics, Measuring & Mapping

Exhibition:

Exhibition Location:

Credit Line: Gift of Ben Wharton Rau and Margery Felsenthal Rau

Data Source: National Museum of American History

Id Number: 1977.1141.17Catalog Number: 336401Accession Number: 1977.1141

Object Name: set square

Physical Description: plastic (overall material)Measurements: overall: .1 cm x 11.2 cm x 11.2 cm; 1/32 in x 4 13/32 in x 4 13/32 in

Guid: http://n2t.net/ark:/65665/ng49ca746aa-913e-704b-e053-15f76fa0b4fa

Record Id: nmah_1213904

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