09-006. American, patent dated Feb-12, 1918, stamped 'THE "SMALL" POCKET CALCULATOR,' and manufactured by the Small Calculator Co., Waltham, Mass. The calculator was originally described as "a six inch, logarithmic slide rule, bent into a circle so as to form a compact and easily operated instrument. It is composed of four fundamental members, as follows:-- (1) A circular Base Plate carrying continuous scales on its periphery and lower face. (2) A movable Top Plate or Rotor arranged to turn on the hub of the first member and carrying similar scales on its periphery and upper face. (3) A slotted Hub Nut to keep the Rotor in place and adjust the friction thereof. (4) A Slider or Runner with cross hair and pointers to be used in conjunction with the first two members..." This very unusual 1 7/8" diameter x 3/8" thick American-made circular slide rule comes with its original shaped leather carrying case and is in very good overall condition, noting a small chip in the rim and 2 very small chips in the enamel (cosmetic only).
