Compass for drawing very small circles - has pivoted fitting to receive lead on one side and pen on other side

摘要

Circles of very small dia. can be drawn in either pencil or ink with a compass (1) with a shank (2). The shank has a needle point (3,4) fitting in a socket in its lower end. A fitting (6) is mounted on the shank on a pivot (7) near the lower end. This fitting is restrained by a spring (8) and can be adjusted by a screw (10). One end of this fitting has a socket (16a) to receive a standard insert (16) which holds the lead. The opposite end of the fitting has a through hole (15) and recess (14) to receive an inking pen.