Keuffel & Esser 4013 Thacher Cylindrical Slide Rule

This desktop slide rule has a cylindrical brass drum covered with paper printed with 40 A scales. A wooden knob is fastened to each end of the drum. The drum fits in an open rotating brass frame; 20 brass slats span the frame. The right side of the paper on the drum is printed in italics: Patented by Edwin Thatcher [sic], C.E. Nov. 1st 1881. Made by Keuffel & Esser Co. N.Y.

The slats are lined with cloth and covered with paper. Each slat is printed with two B and two C scales. 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 fortieth runs from 946 to 100 to 105. The first C scale runs from 100 to 334; the fortieth runs from 308 to 305.

The front of the frame is spanned by a brass pyramidal bar. A brass and metal mount with three thumbscrews is attached to the bar. The mount may be adjusted by height, and it slides along the bar. A magnifying glass was to be positioned on the mount, but it is missing in this example.

The frame is screwed to a mahogany base. A paper with instructions is glued to the top front of the base. The top back of the base is engraved: KEUFFEL & ESSER Co (encircling N.Y.); 4013 (/) 3518; TRADE MARK (below the K&E lion logo). A sticker on the back of the base is marked: DEPARTMENT OF AGRICULTURE (/) 6076 – AMS. This rule was found in the Smithsonian collections, but it was presumably associated with the Agricultural Marketing Service, an agency established within the U.S. Department of Agriculture in 1939. The rule may have been purchased earlier but not inventoried, since AMS was preceded by several government bureaus, including the Office of Markets, which was founded in 1913.

Keuffel & Esser Company of New York 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 4013; the serial number suggests it was manufactured around 1915 and after MA.321789. The marking on the core also no longer references W. F. Stanley, the English firm that originally manufactured the instrument for sale by K&E. Stanley continued to provide the engine-divided scales after K&E began making the rest of the instrument in 1887. K&E took over printing the scales in the 1910s. Model 4013 sold for $45.00 in 1913.

Compare markings on the core to MA.315663. See also MA.327886.

References: Wayne E. Feely, "Thacher Cylindrical Slide Rules," The Chronicle of the Early American Industries Association 50 (1997): 125–127; Catalogue of Keuffel & Esser Co. (New York, 1913), 294; National Archives, "Records of the Agricultural Marketing Service [AMS]," Guide to Federal Records, Record Group 136, http://www.archives.gov/research/guide-fed-records/groups/136.html; "Agricultural Marketing Service," Allgov: Everything Our Government Really Does, http://www.allgov.com/Agency/Agricultural_Marketing_Service__.

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