The first mechanical clock in the world was built by the Buddhist monk and mathematician Yixing in 725. A contemporary text described it as follows:

[It] was made in the image of the round heavens and on it were shown the lunar mansions in their order, the equator and degrees of the heavenly circumference. Water, following into scoops, turned a wheel automatically, rotating it one complete revolution in one day and night [24 hours]. Besides this, there were two rings fitted around the celestial sphere outside, having the sun and moon threaded on them, and these were made to move in circling orbit. Each day as the celestial sphere turned one revolution westwards, the sun made its way one degree eastwards, and the moon 13 7/19 degrees eastwards. After 29 rotations and a fraction of a rotation of the celestial sphere, the sun and moon met. After...