Keuffel & Esser 4045 Mannheim Simplex Slide Rule

This sixteen-inch instrument has a wooden core coated with white celluloid that has yellowed considerably. 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 16 inches, divided to sixteenths of an inch. The front edge has a scale of 41 centimeters, divided to millimeters. A table of numerical ratios and equivalences is pasted to the back of the rule.

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 >. There is a glass "frameless" indicator with metal edges. The top edge is marked: KEUFFEL & ESSER Co (/) NEW YORK. The back of that edge is marked: PAT. APPL'FOR. Keuffel filed for a patent for the design of the frameless indicator on November 25, 1913, and received it in 1915. K&E began to show the indicator in its catalogs that same year. The slide rule sold for $10.00. The company sold model 4045 with this design of indicator until 1936, when the price was $13.00. Compare this example to MA.322761 and MA.308201.

The rule is in a cardboard box covered with black leather. The box is marked: KEUFFEL & ESSER Co. (/) MANNHEIM (/) SLIDE RULE. This instrument was in the possession of Edward Avery, a technician in the Department of Botany at the Smithsonian's National Museum of Natural History, until his death in about 1970. Where he obtained the instrument is not known.

References: Willie L. E. Keuffel, "Slide-Rule Runner" (U.S. Patent 1,150,771 issued August 17, 1915); Catalogue of Keuffel & Esser Co., 35th ed. (New York, 1915), 299; Catalogue of Keuffel & Esser Co., 38th ed. (New York, 1936), 311; accession file.

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