Taylor Adding Machine

Taylor, Elmore W. · 1874

This patent model for a circular adder has a wooden base that supports three concentric wooden rings and a central mechanism. The outer fixed ring is serrated around the outer edge. The 100 serrations are numbered in ink from 1 to 99 (the 0 serration isn’t numbered) on a paper ring glued to the surface of the ring. Inside this ring is a movable ring, with 100 upward-facing serrations around its edge. These are numbered on an adjacent piece of paper from 00 to 99. Inside this ring is a third fixed ring, serrated on the inside, and also carrying a numbered slip of paper numbered from 00 to 99.