Astronomical Clock of Su Song (1020-1101)

The most famous achievement in the annals of Chinese time-keeping is the massive astronomical clock built by Su Song (1020–1101), a diplomat and administrator in the service of the Song Emperor. The clock, first designed in 1086, reproduced the movements of the Sun, Moon, and stars, which were crucial to Chinese calendrical calculation and astrological divination. It consisted of a tall wooden tower (appr. 40 ft), which housed an armillary sphere, a celestial globe, and an ensemble of wheels containing figurines that gave aural as well as visual indications of the time of the day according to hours and quarter-hours. The drive for the entire structure was provided by a water-powered large gear wheel, which automatically started and stopped at fixed intervals.

Commentary. Philipp Nothaft (May-June 2019)