Scope and ContentThe Mannheim 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], not issued before 1939 (L.A. branch listed on cover and title page.) Booklet, 5-1/8" x 7-3/4" high, pp [ii], 75, [2]. Dampstain lower right corner. Manual was for the model numbers 4031, 4035, 4041, 4045, 4051, 4055, 4056 and 4058. Copyright date and issue date are not necessarily the same. Back cover code: 98749