A "Balance Wheel" is a mechanical device used in timekeeping, particularly in watches and clocks. It consists of a small wheel that oscillates back and forth, regulating the movement of the gears. This oscillation helps maintain accurate time by controlling the release of energy from the mainspring. The balance wheel works in conjunction with a hair spring, which is a fine coil that returns the wheel to its central position after each swing. Together, they create a consistent rhythm, allowing the timepiece to keep precise time. The invention of the balance wheel significantly improved the accuracy of mechanical clocks and watches.