The sensitivity of a watch refers to the early or late time when the pendulum wheel in the watch "starts" by itself. One inspection method is to gently shake the watch that has not been winded to stop moving, and observe the movement of the second hand with the help of the shaking force; If the second hand stops moving in a very short time, it means that the watch can be fully loosened after winding up, and the sensitivity is relatively high; If the second hand continues to move for a long time, it means that the watch can not be fully loosened after winding, the sensitivity is not high, or the internal mechanism is faulty.

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.