Keuffel & Esser 4088-3 Polyphase Duplex Slide Rule

This ten-inch duplex linear slide rule is made from boxwood faced with white celluloid and held together with L-shaped metal end pieces. On one side, the base has DF and D scales, with CF, CIF, and C scales on the slide. The bottom of the base is marked: KEUFFEL & ESSER CO. N. Y.; PAT. JUNE 5, '00 DEC. 22, '08. On the other side, there are K, A, D, and L scales on the base and S, T, and CI scales on the slide. Both pieces of the base and the slide are stamped on one end: 13. The indicator is glass in a metal frame with vertical bars on the sides.

Keuffel & Esser introduced this form of slide rule in 1913 as model 4088-3 and sold it with a leather case for $7.00. This style of indicator was used only from 1913 to 1915, when K&E switched to its "frameless" glass cursor. This example thus dates to 1913–1915. Compare to MA.321778, 1981.0933.03, and MA.318480.

References: Willie L. E. Keuffel, "Slide-Rule" (U.S. Patent 651,142 issued June 5, 1900) and "Slide-Rule" (U.S. Patent 907,373 issued December 22, 1908); Catalogue of Keuffel & Esser Co., 34th ed. (New York, 1913), 304a; Catalogue of Keuffel & Esser Co., 35th ed. (New York, 1915), 307b.

Currently not on view