The verge escapement is the oldest known kind of mechanical escapement. It matters because it made the first fully mechanical clocks possible. European tower clocks used it by the late 1200s. In the 1400s it was adapted for portable watches.
How does a verge escapement work?
The escape wheel is called the crown wheel. Its teeth stand at right angles to the wheel’s face. There is always an odd number of them, usually 13. The escapement only works with an odd tooth count. An even count will not do. A rod, the verge, carries two pallets, one upper and one lower. The crown wheel’s teeth push first on the upper pallet and then on the lower one. This makes the verge rod swing back and forth.
Why does a verge watch need a fusee?
Every verge watch needed a fusee to even out the force of the mainspring. Without one, a verge watch could not keep even rough time. The fusee was bulky, and it made verge movements thick. The crown wheel added height too. Its teeth stand upright, so a verge movement has to be tall. Late verge watches were so bulky that people nicknamed them turnips.
What replaced the verge escapement?
Thick movements went out of fashion. The cylinder escapement of 1695 allowed slimmer watches than the verge did, so French makers switched to it. By the 1820s, better escapements had replaced the verge. Cheap verge watches were still made throughout the 1800s, though. In quality watchmaking, the lever escapement eventually replaced the verge and every other competing escapement.
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