The verge (or crown wheel) escapement is…

The verge (or crown wheel) escapement is the earliest known type of 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 it has been suggested that the verge was introduced to Europe from China.

The first hard evidence of the verge escapement dates from early fourteenth-century Europe, where its invention had led to the development of the first all-mechanical clocks.

The earliest clock known to be mechanical had been built in Padua in 1335 by Jacopo de Dondi; perhaps the earliest existing drawing of a verge escapement is that detailing the Astrarium, an astronomical clock created by de Dondi’s son Giovanni, built in 1364 in Padua.

Another example of the innovative verge escapement mechanism drives an ornate clock at Salisbury, constructed in 1396.

The verge escapement will be used in virtually all clocks and watches for four hundred years until, in the wave of seventeenth century horological innovation following the pendulum, it will be replaced by better escapements.