High Quality Content by WIKIPEDIA articles! 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 advancing the gear train at regular intervals or `ticks`. Its origin is unknown. Verge escapements were used from the 14th century until about 1800 in clocks and pocketwatches. The name verge comes from the Latin virga, meaning stick or rod.