1961 U.S. Army TM 6-231 Seven Place Logarithmic Tables Artillery Technical Manual

Original U.S. Army Technical Manual TM 6-231, Seven Place Logarithmic Tables, dated October 23, 1961. This is a massive 497-page reference manual made up largely of detailed logarithmic tables used for artillery calculations before electronic calculators became standard. It includes logarithms of functions of angles in mils, common logarithms of numbers, conversion of degrees to mils and mils to degrees, artillery rounding rules, proportional parts, interpolation, and related calculation methods. The sheer volume of tables makes this an interesting Cold War era artillery and technical reference piece, and a good example of just how much math went into artillery work before modern digital equipment. The cover shows age, edge wear, light staining, and handling marks, but the manual remains solid and readable with the extensive tables intact.