The brass core of this cylindrical slide rule is covered with paper marked with forty A scales. The core fits in an open rotating frame that holds twenty metal slats; each slat is lined with cloth, covered with paper, and marked with two B and two C scales. Wooden knobs on each end of the core rotate the instrument. The frame is attached to a mahogany base.
The first A scale runs from 100 to 112; the fortieth runs from 946 to 100 to 105. The first B scale runs from 100 to 112, the last from 946 to 100 to 105. The first C scale runs from 100 to 334, the last from 308 to 305. The paper covering the core is also printed in italics on the right side: Made by Keuffel & Esser Co., New York; Patented by Edwin Thatcher [sic], C.E. Nov. 1st., 1881.
A paper of instructions and rules for operating THACHER'S CALCULATING INSTRUMENT is glued to the top front of the base. The top back of the base is stamped: KEUFFEL & ESSER CO. (encircling N.Y.); 4012 (/) 4917; TRADEMARK (below the K&E logo of a lion).
The instrument is stored in a mahogany rectangular case. A square off-white label inside the lid is printed: KEUFFEL & ESSER CO. (/) NEW YORK HOBOKEN, N.J. (/) CHICAGO ST. LOUIS SAN FRANCISCO MONTREAL (/) DRAWING MATERIALS, SURVEYING INSTRUMENTS (/) MEASURING TAPES (/) No. 4012 (/) SERIAL 4917.
Keuffel & Esser sold versions of the Thacher cylindrical slide rule from about 1883 until about 1950. There were two models, one with a magnifying glass (K&E model 1741 before 1900, K&E model 4013 after) and one without (K&E model 1740 before 1900, K&E model 4012 after). This is a model 4012; the serial number suggests it was manufactured around 1920. Model 4012 sold for $35.00 in 1916, $60.00 in 1922, and $70.00 in 1927.
The National Bureau of Standards (now the National Institute of Standards and Technology) declared this object excess property and transferred it to the Smithsonian in 1965. In 1968, the Department of Commerce borrowed the slide rule to exhibit in the U.S. Pavilion at HemisFair, an international exposition held in San Antonio, Tex. According to the accession file, a staffer replaced four missing screws on the base before returning the rule.
See also MA.312866; MA.323504; and MA.322730.
References: Wayne E. Feely, "Thacher Cylindrical Slide Rules," The Chronicle of the Early American Industries Association 50 (1997): 125–127; Keuffel & Esser Co., Slide Rules and Calculating Instruments (New York, 1916), 22; Keuffel & Esser Co., Slide Rules and Calculating Instruments (New York, 1922), 21; Keuffel & Esser Co., Slide Rules and Calculating Instruments (New York, 1927), 20.
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