Keuffel & Esser 4088-3 Polyphase Duplex Slide Rule

This ten-inch mahogany duplex linear slide rule is coated with white celluloid and held together with L-shaped metal end pieces. The front of the base has DF and D scales, with CF, CIF, and C scales on the slide. The right end of the slide is marked in red: < 4088-3 >. The bottom of the base is marked in red: PAT. JUNE 5. '00 DEC.22.'08 KEUFFEL & ESSER CO. N.Y. MADE IN U.S.A. The owner's name is scratched on the slide and on the base: ELLENBERGER.

The back of the base has K, A, D, and L scales, with B, S, T, and CI scales on the slide. A serial number is at the left end of the slide and on the front edge: 161313. The indicator is frameless glass with white plastic edges and metal screws. One edge is marked: K&E.CO.N.Y. (/) PAT.8.17.15. A cardboard case covered with blue leather is not original to this object and is marked: MICRONTA (/) Made in Germany. It also has an owner's label: Wm. J. Ellenberger.

Keuffel & Esser Company of New York added a B scale to model 4088-3 in 1922. The indicator was modified in 1936. The serial number suggests a manufacturing date around 1927. Between 1922 and 1936, model 4088-3 sold in a box for $8.50. For instructions, see 1981.0933.04 and 1981.0933.06. Compare this example to MA.318476, MA.318480, and MA.321778.

William J. Ellenberger (1908–2008) was born in Nashville, Tenn. He enrolled in The George Washington University in 1925, earning BS degrees in electrical engineering (1930) and mechanical engineering (1934). It seems likely that Ellenberger acquired and used this slide rule while he studied at GWU. He went on to work for the Potomac Electric Power Company (PEPCO), the National Bureau of Standards, and the U.S. Army.

References: Catalogue of Keuffel & Esser Co., 36th ed. (New York, 1921), 239; Keuffel & Esser Co., Slide Rules and Calculating Instruments (New York, 1922), 8–9; Catalogue of Keuffel & Esser Co., 38th ed. (New York, 1936), 314–315; Ed Chamberlain, "Estimating K&E Slide Rule Dates," 27 December 2000, http://www.sphere.bc.ca/test/ke/320-k+e_date2.jpg; accession file.

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