Keuffel & Esser 4045 Mannheim Simplex Slide Rule

This sixteen-inch instrument has a wooden core coated with white celluloid. There are A and D scales on the base, with B and C scales on one side of the slide; the scales are not labeled with letters. The reverse of the slide has S, T, and L scales, which are labeled with these letters. The top edge is beveled and has a scale of inches, divided to sixteenths of an inch. The front edge has a scale of centimeters, divided to millimeters. A table of numerical ratios and equivalences is pasted to the back of the rule. A glass "frameless" indicator has plastic edges.
The base is marked in red: KEUFFEL & ESSER CO. N.Y.; PAT. JUNE 5, 1900. K&E head of manufacturing Willie L. E. Keuffel received this patent for a method of adjusting a slide rule, accomplished with four screws on the back of the instrument. The left end of the slide is marked in red: < 4045 >. K&E first advertised model 4045 in 1906. The edge of the indicator is marked: K&E.CO.N.Y. (/) PAT.8.17.15. Keuffel also took out this patent, for the design of the frameless indicator. Since the plastic on the indicator is the same color as the rule and thus probably original to the instrument, this example was likely made after 1915. The indicator was changed again in 1936, and K&E no longer made this model by 1939.
The rule is in a cardboard box faced with dark brown leather. The box is marked: KEUFFEL & ESSER Co. (/) MANNHEIM (/) SLIDE RULE. The instrument was found in a Smithsonian storage court and catalogued in 1963. The indicator was broken in 2005 and is now stored in a separate bag. Compare this example to 1987.0634.01 and MA*308201.
References: Willie L. E. Keuffel, "Slide-Rule" (U.S. Patent 651,142 issued June 5, 1900); Willie L. E. Keuffel, "Slide-Rule Runner" (U.S. Patent 1,150,771 issued August 17, 1915); Wayne E. Feely, "K & E Slide Rules," The Chronicle of the Early American Industries Association 49, no. 5 (June 1996): 50–52; Clark McCoy, "Collection of Pages from K&E Catalogs for the 4041 Family,"; Catalogue of Keuffel & Esser Co., 32th ed. (New York, 1906), 322; Catalogue of Keuffel & Esser Co., 35th ed. (New York, 1915), 299; Catalogue of Keuffel & Esser Co., 38th ed. (New York, 1936), 311.
Currently not on view
Object Name
calculating rule
slide rule
date made
Keuffel & Esser Co.
Physical Description
celluloid (laminate material)
wood (overall material)
glass (cursor material)
cardboard (case material)
overall: 1.6 cm x 42 cm x 4.1 cm; 5/8 in x 16 17/32 in x 1 5/8 in
ID Number
accession number
catalog number
Rule, Calculating
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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