Concise CTCS-552 Circular Slide Rule

Concise CTCS-552 Circular Slide Rule

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This white plastic circular slide rule is on a rectangular base that has a 4-inch ruler on the left side and a 10-cm ruler on the right. The top of the base is marked: CONCISE (/) CONVERSION TABLES (/) AND CIRCULAR SLIDE RULE. The slide rule has a D scale along the outer rim. A rotating disc fastened with a metal grommet has C, CI, L, A, and K scales. There is a clear plastic rotating indicator. The bottom of the base is marked: MODEL CTCS-552.
The back of the instrument has a table of the chemical elements, arranged in alphabetical order, and a chart for converting temperatures from Celsius to Fahrenheit. The bottom of the back is marked: MODEL CTCS-552 (/) SAMA & ETANI, INC. GROTON MASSACHUSETTS U.S.A. (/) MADE IN JAPAN BY CONCISE.
A rectangular plastic card fits inside a slot in the base. The card provides various physical constants and conversions for length, area, weight, volume, decimal equivalents to 64ths, velocity, gas constant values, flow rate, pressure, and energy. One edge of the card is marked: ©1966 CONCISE INTERNATIONAL CO., LTD. The instrument and an instruction manual providing contact information for Sama & Etani and copyrighted 1960 both fit in a black plastic case.
Domenick Sama and Kenzi Etani designed this style of slide rule and conversion card when they were students at the Massachusetts Institute of Technology in 1954. By the mid-1960s, Concise, a firm in Tokyo, Japan, was manufacturing the device for Sama & Etani, who in turn were distributing Concise's products through their partnership headquartered in Groton, Mass. In Japan, the company operated as Etani Shoji Kaisha, Ltd. It closed by 1992. Concise began operating under the name Concise International Co., Ltd., in 1966 and remains in business as of 2012. For other slide rules by Concise, see 1996.0141.01, 2003.0012.01, and 2006.0173.01.
References: "Concise Corporate History,"; Peter M. Hopp, Slide Rules: Their History, Models, and Makers (Mendham, N.J.: Astragal Press, 1999), 153–154; "Groton Engineer, Associate Design Pocket Size Rule," Groton Town Diary 13 (March 1967): 17,
Currently not on view
Object Name
slide rule
date made
after 1966
place made
Japan: Tōkyō, Tokyo
Physical Description
cardboard (part material)
metal (part material)
plastic (overall material)
overall:.5 cm x 8.8 cm x 11.6 cm; 3/16 in x 3 15/32 in x 4 9/16 in
ID Number
accession number
catalog number
Credit Line
Gift of Edward L. Heller
Rule, Calculating
Conversion Chart
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Slide Rules
Data Source
National Museum of American History
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I now realize I must be really old, for I have one of these in my possession. The company my father worked for gave them away to their customers.

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