Fusee chain and spring-box, being the prime mover in some watches, particularly of English make. The fusee to the right is to compensate for the loss of force of the spring as it uncoils itself. The chai motion. The teeth of these gears, being is on the small diameter of the fusee when oblique, give a more continuous bearing the watch is wound up, as the spring has than ordinary spur-gears. then the greatest force.