Fly or Fan
A fan having two blades, used for preserving the uniformity of motion, as in music-boxes and the striking mechanism of clocks. The resistance of the air on the fan blades prevents the train from accelerating.
How to true a balance, repair a chipped dial, temper a spring or test a stone — the working bench-book of the American watch trade, arranged A to Z.
A fan having two blades, used for preserving the uniformity of motion, as in music-boxes and the striking mechanism of clocks. The resistance of the air on the fan blades prevents the train from accelerating.