Beautiful first period Cartel clock in perfect condition. Dial signed Courtois H.ger Du Roi Sui La Cour, has a crowwheel escapement. Courtois was a clock and watchmaker in French from 1750-1772. He invented sliding carillon barrel moved by cam, approved by Academy of Science. The verge (or crown wheel) escapement is the earliest known type of mechanical escapement. Verge escapements were used from the 14th Century until about 1800 in clocks. The name verge comes from the Latin Virga, meaning stick or rod. In mechanical clocks, and escapement is a device which converts continuous rotational motion into an oscillating or back and forth motion. It is the source of the ‘ticking’ sound produced by clocks.