Early gear-driven watches were equipped with a single hand, ie. an hour hand. Abraham-Louis Breguet's famous "Souscription" pocket watch was a one-hand watch. The time can only be approximated by consulting the dial of a one-handed watch. Wristwatches of this type are rare, but not entirely nonexistent.

In a self-winding movement, the oscillating mass is a body free to rotate and connected to the barrel by a gear train. When the movement is in a non-horizontal position, gravity causes this heavy mass to fall toward the center of the Earth. The kinetic energy generated during this fall is transferred by a gear train to the barrel, where the main spring stores it as potential energy.