Keuffel & Esser 68-2047 Log Log Duplex Decitrig Manual and S14-5 Care Instructions

ID number 1987.0085.01, a model 68–1210 Log Log Duplex Decitrig slide rule by Keuffel & Esser of New York, was received with these two paperback booklets. The citation information for the first booklet is: Lyman M. Kells, Willis F. Kern, and James R. Bland, K&E Slide Rule Manual: Log Log Duplex Decitrig, 4th ed. (New York: Keuffel & Esser Co., 1955). Kells, Kern, and Bland were all mathematics professors at the United States Naval Academy; they first prepared this manual in 1943. They designed the book for students to learn to operate slide rules on their own, without the aid of a teacher.

The manual covers the following topics: multiplication and division; the proportion principle and combined operations; squares and square roots, cubes and cube roots; trigonometry; the log log scales; and logarithms and the slide rule. Included are exercises, answers, and a historical note (featuring K&E's contributions to the development of slide rules). The manual was previously K&E model number 4187S.

The second pamphlet is small (4 X 3 inches) and titled: "How to Take Care of Your Slide Rule." It was copyrighted in 1944, 1949, 1958, and 1962. Users are to clean the slide rule only with a moistened cloth. Instructions are provided for adjusting and aligning the slide rule.

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