Keuffel & Esser 4012 Thacher Cylindrical Slide Rule

This desktop slide rule is in a wooden case that is significantly deteriorated on its inside. The rule has a cylindrical brass drum covered with paper printed with forty A scales. A wooden handle is fastened to each end of the drum. The drum fits in an open rotating brass frame; twenty 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. Divided by W. F. Stanley, London, 1882. 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 frame is screwed to a mahogany base. A paper with instructions is glued to the top front of the base. An ivory label for Keuffel & Esser Co. is screwed to the front right corner. The top back of the base is engraved: KEUFFEL & ESSER Co (encircling N.Y.); 4012 (/) 1689; TRADE MARK (below the K&E lion logo). Another ivory K&E label is fastened inside the lid of the case. A paper K&E label pasted inside the lid is stamped in faded purple ink: No. 4013 (/) Serial 1689. Written in pencil is: Mar 22/07.
The Thacher cylindrical slide rule was sized for a desk, but its scales were equivalent to those on a conventional slide rule over 59 feet long. It had scales for multiplication, division, and squares and square roots. There were no trigonometric scales.
Keuffel & Esser sold model 4012 from 1900 to about 1950. The markings and serial number indicate this example dates to 1907. Model 4012 cost $35.00 in 1909. The U.S. Department of Agriculture transferred this example to the Smithsonian in 1964.
See also MA*312866, MA*326628, and MA*323504.
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., 33rd ed. (New York, 1909), 304.
Currently not on view
date made
Keuffel & Esser Co.
place made
United States: New York, New York
Physical Description
wood (part material)
cloth (part material)
brass (overall material)
paper (part material)
overall: 16.5 cm x 60.2 cm x 17 cm; 6 1/2 in x 23 11/16 in x 6 11/16 in
ID Number
accession number
maker number
catalog number
Credit Line
Transfer from U.S. Department of Agriculture
Rule, Calculating
U.S. National Government, executive branch
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Slide Rules
Data Source
National Museum of American History, Kenneth E. Behring Center


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