The verge (or crown wheel) escapement is the earliest known type of mechanical escapement, the mechanism in a mechanical time piece that controls its rate by allowing the gear train to advance at regular intervals or 'ticks'. Its origin is unknown. Verge escapements were used from the 14th century until the mid 19th century in clocks and pocketwatches. The name verge comes from the Latin virga, meaning stick or rod.
Its invention is important, because it made possible the development of the original-mechanical clocks. This caused a shift from measuring time by processes, such as the flow of liquid in water clocks. (Wikipedia).
A verge pocket watch movement signed by W. Private made in the 18th century.
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