Barbour Calculating Machine

Barbour, Edmund D. · 1875

This small brass U.S. Patent Office model of a calculating machine is a modification of Edmund D. Barbour’s two earlier machines. It has a rectangular base on which is mounted crosswise a rotating cylinder. The cylinder has nine crosswise grooves that fill somewhat less than a quarter of the surface. Metal bands separate the grooves into columns, and each column has a set of nine sliding markers that fit in the grooves. Sliding these markers sets a number. There also is an array of pins around the cylinder, which is used in carrying. There are gears on both sides of the cylinder.