Timing instruments of mechanical vibration system, such as pendulum clock, pendulum clock, etc. Its working principle is to use a vibration system with constant period and continuous vibration. Multiply the vibration period during vibration by the number of vibration times, which is equal to the elapsed time. Time=the vibration period of the watch × Number of vibrations. It is generally composed of energy, gear train, escapement mechanism, vibration system, pointer mechanism and additional mechanism.