Anchor escapement teeth, which made the escape wheel rotate once per minute so the second hand could be attached to its shaft. In a 30 tooth escape wheel the pallets span about 7½ teeth. The impulse angle of the pallets, which determined the swing of the pendulum, was 3°-4°. The anchor was the second widely used escapement in Europe, replacing the 400-year-old verge escapement in pendulum clocks. The pendulums in verge escapement clocks had very wide swings of 80° to 100°. In 1673, seventeen years after he invented the pendulum clock, Christiaan Huygens published his mathematical analysis of pendulums, "Horologium Oscillatorium". In
Watch Nevertheless, the craftsmanship of mechanical watches still attracts interest from part of the watch-buying public, especially among the watch collectors. Skeleton watches are designed to leave the mechanism visible for aesthetic purposes. A mechanical movement uses an escapement mechanism to control and limit the unwinding and winding parts of a spring, converting what would otherwise be a simple unwinding into a controlled and periodic energy release. A mechanical movement also uses a balance wheel together with the balance spring (also known as a hairspring) to control the motion of the gear system of the watch in a manner analogous to