Scope and ContentK&E Slide Rule Manual; Modern Polyphase. By Lyman M. Kells, Willis F. Kern & James R. Bland. Manual No. 68 2061 (Old No. 4187Y.) Published by Keuffel & Esser, New York and Hoboken, no date, circa 1962-1963. (Copyright 1952.) Softcover, 5-1/4" x 8" high, 92 pp. Even though the text is copyrighted 1952, the "Modern Polyphase" name was first used for a group of slide rules in 1962 along with the stock number 68 2061 for this manual. This preface states this "manual has been written for study without the aid of a teacher." The slide rule model numbers covered by the instructions are not named, but it would have been for the 68 1581 (old number 4161-1 - introduced in 1952 and thus the 1952 copyright date) and the 68-1576 (old number 4161-3 - introduced in 1954). It may also have applied to the 68-1586. The 4161 group were Mannheim type slide rules. These materials are from the personal papers of employee George Edler who worked for K&E from 1954-1984.