Keuffel & Esser 4087 T Duplex Slide Rule

This 20-inch duplex mahogany slide rule is completely coated with white celluloid and held together with the L-shaped metal end pieces Keuffel & Esser adopted in 1913. The indicator is of the frameless glass type K&E first used in 1915. The edges are metal, not plastic, and one edge is marked: PAT. APPL'D FOR. On one side, the base has A and D scales, with B, S, and C scales on the slide. The left end of the slide is marked with the model number: < 4087 T >. The left edge of each piece of the rule is stamped with the number 18. The bottom of the base is marked: KEUFFEL & ESSER CO. N.Y.; PAT. JUNE 5, '00 DEC. 22, '08. For information on these patents, see MA.322761 and MA.318475.

On the other side, the base has A, D, and L scales, with BI, T, and CI scales on the slide. The trigonometric scales are divided into degress and minutes. The rule fits into a cardboard box covered with black leather and marked: KEUFFEL & ESSER Co. (/) DUPLEX (/) REG. U.S. PAT. OFF. (/) SLIDE RULE. Introduced in 1909, the 4087 T was discontinued after 1915. K&E only used this combination of scales on this model from 1913 to 1915. It sold for $18.00. The Interstate Commerce Commission transferred this example to the Smithsonian in 1962.

References: Willie L. E. Keuffel, "Slide-Rule" (U.S. Patent 651,142 issued June 5, 1900), "Slide-Rule" (U.S. Patent 907,373 issued December 22, 1908), and "Slide-Rule Runner" (U.S. Patent 1,150,771 issued August 17, 1915); Catalogue of Keuffel & Esser Co., 33th ed. (New York, 1909), 312; Catalogue of Keuffel & Esser Co., 34th ed. (New York, 1913), 303; Catalogue of Keuffel & Esser Co., 35th ed. (New York, 1915), 303.

Currently not on view