6" Tachometer with cross-pendulum movement

6" Tachometer with cross-pendulum movement, reading from 600 to 2400 revs. per minute, with glass dial showing interior; with stand and 4" diam. pulley, no.22065. One woodcut of same, framed 8" x 6"

This instrument indicates directly on a dial, in rev. per min., the speed at which an engine shaft, etc., to which it is connected by a belt drive, is running.