Watches are complicated and contain sophisticated features created with painstaking accuracy. One of these internal features is the balance wheel, which as its name suggests, keeps everything in balance. Balance wheels are used in mechanical watches and have a similar function to that of a pendulum. The weight of the wheel rotates by a spiral spring and is driven by the escapement.
Each swing of the wheel allows the gear train to move a certain amount thus propelling the hand forward. One can imagine the importance of the balance wheel’s design when as such a small piece of the watch it is responsible for so much. The balance wheel was invented in the 14th century and now they are found in every timekeeping device.