SU SONG (c. 1020–1101), Chinese polymath, scientist, inventor, and statesman who built an astronomical clock tower that was by far the most advanced such instrument of its day and anticipated by centuries similar developments in Europe.
Born in modern-day Fujian province during the Song dynasty (c. 960– 1279), Su Song excelled at his studies and easily passed the exams to enter the state bureaucracy. His talents were so prodigious and varied that he served in many different governmental departments, including the ministries of personnel and justice, and eventually attained the post of vice president of the chancellery secretariat.
In 1077 Su Song was sent on a diplomatic mission to the Khitan people of the Liao dynasty to the north but somehow arrived one day late. The confusion was dispelled when Su Song learned that the Khitan, who were thought by the Han Chinese to be “barbaric” and primitive, employed a different, more advanced calendrical system than the Song empire. When Su Song reported his discovery to the Song emperor the latter was so incensed that he fired the officials responsible for keeping time and commissioned Su Song to build his clock tower in order to compete with the Liao.
Su Song promptly set to work and completed his hydraulic astronomical clock tower in 1092. It stood twelve meters high and not only kept precise time but also displayed the positions of celestial bodies, phases of the moon, and other astronomical phenomena. Water flowed through a series of channels and reservoirs, activating gears and pulleys that controlled the motion of celestial dials and indicators; this ingenious design showcased Su Song’s mastery of both mechanical engineering and hydraulic principles, setting a new standard for clock-making and timekeeping in medieval China. Su Song authored the companion essay “New Treatise on the Celestial Clock,” which documented his observations, theories, and inventions related to celestial phenomena. In this seminal work, Su Song elucidated the principles of celestial motion, lunar cycles, and planetary orbits, drawing upon his meticulous observations and empirical data.
Decades after Su Song’s death his clock tower was disassembled by marauding Jurchen invaders from Manchuria and the individual components carted back to their capital Beijing, but when they attempted to reconstruct the tower they could not do so. And when the subsequent Qing emperor commissioned Su Song’s son Su Xie to reconstruct his father’s masterwork based on Su Song’s treatise, Su Xie likewise came up short, claiming his father must have left out vital information.