Balance wheel

·- A wheel which imparts regularity to the movements of any engine or machine; a fly wheel.

II. Balance wheel ·- A wheel which regulates the beats or pulses of a watch or chronometer, answering to the pendulum of a clock;

— often called simply a balance.

III. Balance wheel ·- A ratchet-shaped scape wheel, which in some watches is acted upon by the axis of the balance wheel proper (in those watches called a balance).