Before 1300 years ago, human beings mainly used the continuous movement of time by astronomical phenomena and flowing materials. For example, the sundial is timed according to the orientation of the sun's shadow; When clepsydra and hourglass are flow meters that use water and sand.

In the Eastern Han Dynasty, Zhang Heng made a leak-turning armillary sphere, and connected the elephant with a timed leak kettle by a gear system. The leaky kettle drips water to push the elephant to rotate evenly, once a day. This is the earliest mechanical clock.

Extended data

The principle of clocks and watches

Clocks and watches have a wide range of applications and many varieties, which can be classified according to vibration principle, structure and application characteristics.

According to the principle of vibration, it can be divided into clocks and watches that use low-frequency mechanical vibration, such as pendulum clocks and balance clocks. Clocks and watches that use high-frequency electromagnetic oscillation and synchronous oscillation, such as synchronous clocks and synchronous clocks;

According to the structural characteristics, it can be divided into mechanical watches, such as mechanical alarm clock, automatic, calendar, double calendar, clockwork, etc. Electromechanical, such as electric pendulum clock, electric balance wheel clock, etc. ; Electronic clock, such as balance wheel electronic clock, tuning fork electronic clock, pointer and digital display time electronic clock, etc.