will's watch pages
How a watch works 1: Mainspring and motion work
The mainspring that powers the watch, a spiral ribbon of spring steel, is inside a cylindrical barrel, with the outer end of the mainspring attached to the barrel. The force of the mainspring turns the barrel. The barrel has gear teeth around the outside that turn the center wheel once per hour — this wheel has a shaft that goes through the dial. On the dial side the cannon pinion is attached with a friction fit (allowing it to slide when setting the hands) and the minute hand is attached to the cannon pinion. The cannon pinion drives a small 12-to-1 reduction gearing called the motion work that turns the hour wheel and hand once for every 12 revolutions of the minute hand.
4. Barrel lid
Barrel with mainspring