Keuffel & Esser Instruction Manual for Mannheim and Polyphase Duplex Slide Rules

This 72-page salmon-colored paperback book was received with 1981.0933.03 and 1981.0933.05. Its citation information is: William Cox, The Mannheim (Polyphase) and the Duplex (Polyphase-Duplex) Slide Rules Complete Manual (New York: Keuffel & Esser Co., 1920). It sold for 50 cents. William Cox helped introduce the Mannheim slide rule to the United States, invented the duplex slide rule, and served as a mathematical consultant to Keuffel & Esser Company of New York, thus launching that firm into pioneering the American manufacture of slide rules. He wrote this manual in 1891. It was revised in 1917, adding instructions for K&E's Polyphase Duplex slide rule (model 4088-3). Cox died in 1907; the author of the revisions is unknown.

A notice inside the front cover explained how K&E had updated the Mannheim line (models 4031–4056) since Cox first wrote the manual. The revised manual thoroughly described the characteristics, operations, and scales of Mannheim and Polyphase (which was especially useful for problems involving powers or roots) slide rules. It provided a lengthy table of equivalents for the base scales, C and D, as well as methods for working out mechanical and other formulas. It then went through a similar discussion for the eight-inch Duplex rule (model 4065) and for the ten-inch Polyphase-Duplex rule (model 4088). A supplement by J. M. Willard of the State College of Pennsylvania addressed the solution of problems in plane trigonometry. Finally, there are advertisements for K&E's general and specialty slide rules, the frameless indicator patented in 1915, a magnifier, and surveying equipment.

References: William Cox, "Engineer's Slide-Rule" (U.S. Patent 460,930 issued October 6, 1891); Florian Cajori, A History of the Logarithmic Slide Rule and Allied Instruments (New York: Engineering News Publishing Company, 1909); Dieter von Jezierski, Slide Rules: A Journey Through Three Centuries, trans. Rodger Shepherd (Mendham, N.J.: Astragal Press, 2000), 14, 35; Clark McCoy, ed., "K&E Slide Rule Manuals," http://www.mccoys-kecatalogs.com/KEManuals/manuals.htm.

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