Verge escapement

Verge escapement and balance wheel from an early pocketwatch

Verge and foliot escapement from De Vick tower clock, built in Paris, 1379, by Henri de Vick

The verge (or crown wheel) escapement is the earliest known type of mechanical escapement, the mechanism in a mechanical clock that controls its rate by allowing the gear train to advance at regular intervals or 'ticks'. Verge escapements were used from the late 13th century until the mid 19th century in clocks and pocketwatches. The name verge comes from the Latin virga, meaning stick or rod.^[1]

Its invention is important in the history of technology, because it made possible the development of all-mechanical clocks. This caused a shift from measuring time by continuous processes, such as the flow of liquid in water clocks, to repetitive, oscillatory processes, such as the swing of pendulums, which had the potential to be more accurate.^[2][3] Oscillating timekeepers are used in most modern timepieces.^[2][4][5]