Pocket Revolution Counter, A. Sainte's 1877 patent, with wooden carrying case

Pocket Revolution Counter, A. Sainte's 1877 patent, with fabric covered wooden carrying case, plus plum-bob and three other components

This is a pocket counter, patented by Mr. A. Sainte in 1877, provided with fittings by which it will readily connect with any revolving shaft, if the end be accessible. When this is not the case a small wooden roller, the circumference of which is one-tenth of a yard, is slipped on the counter and employed to measure the circumferential velocity of the shaft, pulley, or belt. A small plumb-bob is also included which can be used as a seconds pendulum for giving the time. The instrument is provided with a handle so that it can be pressed against the revolving shaft, and the motion obtained drives a single worm that gears into a lower worm-wheel of 100 teeth, having a graduated disc. On the spindle of this wheel is a pinion of ten teeth gearing into a wheel of 100 teeth, the disc of which is also graduated, the total ratio being such that one revolution of the hundreds dial corresponds with 1,000 rev. on the shaft. The arm carrying the worm-wheel is hinged, so that the whole counter can be thrown out of action without removing it from the shaft, or the gear can be disengaged for bringing the dials to zero.