Keuffel & Esser 4088-5 Polyphase Duplex Slide Rule

This duplex linear slide rule is made of mahogany coated with celluloid. There are DF and D scales on one side of the base and K, A, D, and L scales on the other side. There are CF, CIF, and C scales on one side of the runner and B, S, T, and CI scales on the other side. The scales are 20 inches long (the "5" in the model number refers to a rule with scales 20 inches long) and closely divided. The indicator is made of glass with a plastic frame.

The base is marked: KEUFFEL & ESSER CO.N.Y.; PAT. JUNE 5. ’00; DEC. 22. ’08; MADE IN U.S.A. The runner is marked: 4088-5. The serial number, on the other side of the runner, is: 72287. The slide rule is stored in a dark brown cardboard and glued leather box.

Keuffel & Esser published catalogs in 1899, 1902, 1905, 1909, 1912, 1915, 1921, 1927, and 1936. Model 4088-2 (8 in.) and 4088-3 (10 in.) slide rules first appeared in the 1913 printing of the 1912 catalog (facing p. 304). Model 4088-5 was first mentioned in 1921 (p. 239) and then again in 1927 (p. 302). In 1927 and in the 1930s (but not in 1921), the front of the runner had a B scale in addition to the S, T, and CI scales. By 1936, the 4088-5 was replaced by the N4088-5 (p. 314). On this basis, the rule dates from between 1922 and 1935. Additionally, the donor reported that he received the slide rule from a friend in about 1930. The instrument sold for $20.00 in 1927. Compare this object to 318476 and 1986.0790.02.

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); Peter M. Hopp, Slide Rules: Their History, Models, and Makers (Mendham, N.J.: Astragal Press, 1999), 193; Clark McCoy, Keuffel & Esser Catalogs, http://www.mccoys-kecatalogs.com.

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