Slide-rule to indicate geometric mid-point between two points on object, uses two cursors, each mounted on endless cable which runs around the ends of scaled ruler

摘要

The slide-rule uses two cursors, each of which are linked to an endless cable (7). The cable runs around pulleys in the end housings (1, 4) of the scaled ruler (2). The edge of each cursor (8, 9) is lined up with the one of the two points. The center point (10) of the rule indicates the mid-point between the two points on the object.