Gilson Midget Circular Slide Rule

Description
This two-sided circular slide rule is a white plastic disc with two transparent, pivoting green plastic arms on one side and a third arm on the back. On the front, from the edge to the center, there is a C scale, CI scale, a scale of logarithms, a scale of squares, a "binary" scale, a log-log scale, a scale for the decimal equivalent of fractions, a scale of drill sizes, and a scale of thread sizes. The rule is marked: MADE IN U.S.A. (/) Copyrighted 1936 (/) Patented.
Three concentric circles forming a scale of degrees, sines, and tangents are on the back. Inside this scale is a scale of decimal equivalents for fractions. The back of the instrument is marked: COPYRIGHTED (/) 1931.
The rule has a green synthetic leather case. On the inside of the flap, it is marked in ink: Donald Mela, and stamped in red: Gordon's (/) DRAFTING MATERIALS (/) 162 W. Madison St. Chicago. The instrument was received with a small paper manual, 1998.0119.03. See also 1989.0032.01.
Claire A. Gilson founded the Gilson Slide Rule Company in Niles, Mich., in 1915. The firm moved to Stuart, Fla., in 1927 and remained in business until about 1975. This example of the firm's Midget model was probably manufactured around 1940.
References: Henry Aldinger and Ed Chamberlain, "Gilson Slide Rules," Journal of the Oughtred Society 9, no. 1 (2000): 48–60 and 9, no. 2 (2000): 47–58; Bobby Feazel, "[Letters of] Richard A. Gilson," Journal of the Oughtred Society 2, no. 2 (1993): 8–12; Ross Grable, "Analysis of a Gilson Circular Rule," Journal of the Oughtred Society 7, no. 1 (1998): 53–55; International Slide Rule Museum, "Time Line for Gilson Slide Rule Company," http://sliderulemuseum.com/SR_Dates.htm#Gilson.
Location
Currently not on view
date made
ca 1940
maker
Gilson Slide Rule Company
place made
United States: Florida, Stuart
Physical Description
metal (part material)
plastic (overall material)
cloth (case material)
Measurements
overall: 11.6 cm x 12.4 cm x .5 cm; 4 9/16 in x 4 7/8 in x 3/16 in
ID Number
1998.0119.01
catalog number
1998.0119.01
accession number
1998.0119
Credit Line
Gift of Donald F. Mela
subject
Rule, Calculating
Mathematics
Manufacturing
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Trigonometry
Slide Rules
Data Source
National Museum of American History, Kenneth E. Behring Center

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