Concise CTCS-552 Circular Slide Rule

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," http://www.concise.co.jp/eng0731/history.html; 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, http://books.gpl.org/greenstone/collect/towndiar/index/assoc/D5248.dir/Vol13_1967_017.pdf.

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