Otis King's Pocket Calculator Model L Cylindrical Slide Rule
Otis King's Pocket Calculator Model L Cylindrical Slide Rule
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- Description
- This six-inch cylindrical slide rule consists of a chromium-plated holder, a metal cylinder that slides into the holder, and a black metal tube that fits around and slides up and down on the cylinder. The telescoping rule is ten inches long when extended and equivalent to a rectangular slide rule 66 feet in length. Two short white lines on the tube and a black mark on the chrome cap at the end of the cylinder serve as the indicator. A paper spiral logarithmic scale is attached to the top half of the holder. A second, linear and logarithmic, paper scale is attached to the cylinder. The logarithmic scales are used to multiply and divide, and the linear scale is used to find logarithms.
- At the top of the cylinder is printed: PATENT No 183723. At the bottom of the cylinder is printed: OTIS KING'S POCKET CALCULATOR; SCALE No 430. The top of the scale on the holder is printed: SCALE No 429; COPYRIGHT. The bottom is printed: OTIS KING'S PATENT No 183723. The end of the holder is engraved: MADE IN (/) Y9481 (/) ENGLAND.
- Otis Carter Formby King invented this form of slide rule in 1921, and Carbic Limited of London, England, manufactured it until 1972. The serial number, Y9481, suggests a date about 1965–1969 for this example. A collector of computing devices donated it to the Smithsonian.
- See also 1987.0788.01 and 1989.3049.02. For documentation, see 1981.0922.10 and 1981.0922.11.
- References: Peter M. Hopp, Slide Rules: Their History, Models, and Makers (Mendham, N.J.: Astragal Press, 1999), 274, 281; Otis Carter Formby King, "Calculating Apparatus," (U.S. Patent 1,645,009 issued October 11, 1927); Richard F. Lyon, "Dating of the Otis King: An Alternative Theory Developed Through Use of the Internet," Journal of the Oughtred Society 7, no. 1 (1998): 33–38; Dick Lyon, "Otis King's Patent Calculator," http://www.svpal.org/~dickel/OK/OtisKing.html.
- Location
- Currently not on view
- Object Name
- calculating rule
- slide rule
- date made
- ca 1965-1968
- maker
- Carbic Limited
- place made
- United Kingdom: England, London
- Physical Description
- chromium (overall material)
- paper (part material)
- metal (part material)
- Measurements
- overall: 15 cm x 3.1 cm x 3.1 cm; 5 29/32 in x 1 7/32 in x 1 7/32 in
- ID Number
- 1981.0922.09
- catalog number
- 1981.0922.09
- accession number
- 1981.0922
- Credit Line
- Gift of John White
- subject
- Rule, Calculating
- Engineering
- Mathematics
- See more items in
- Medicine and Science: Mathematics
- Science & Mathematics
- Slide Rules
- Data Source
- National Museum of American History
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