Scope and ContentThe Polyphase Slide Rule. A Self Teaching Manual with tables of settings, equivalents and guage points. By William E. Breckenridge. Published by Keuffel & Esser Co., New York & Hoboken, N.J., [copyright 1938, 1944], issued circa 1944-1947. Booklet, 5-1/8" x 7-11/16" high, pp [ii], 83, [2]. This is the first printing with the old K&E griffin trademark. A second printing, slightly revised, was issued in 1947 with a new cover design incorporating the 1942 modern K&E logo.