Engineering thumb|A square bronze mirror with a phoenix motif of gold and silver inlaid with lacquer, 8th century Technology during the Tang period was built also upon the precedents of the past. Previous advancements in clockworks and timekeeping included the mechanical gear systems of Zhang Heng (78–139) and Ma Jun (), which gave the Tang mathematician, mechanical engineer, astronomer, and monk Yi Xing (683–727) inspiration when he invented the world's first clockwork escapement mechanism in 725. This was used alongside a water clock and waterwheel to power a rotating armillary sphere in representation of astronomical observation. Yi Xing's device also had a mechanically timed bell that was struck automatically every hour, and a drum that was struck automatically every quarter-hour; essentially, a striking clock. Yi Xing's astronomical clock and water-powered armillary sphere became well known throughout the country, since students attempting to pass the imperial examinations by 730 had to write an essay on the device as an exam requirement. However, the most common type of public and palace timekeeping device was the inflow clepsydra. Its design was improved by the Sui dynasty engineers Geng Xun and Yuwen Kai. They provided a steelyard balance that allowed seasonal adjustment in the pressure head of the compensating tank and could then control the rate of flow for different lengths of day and night.
Engineering thumb|A square bronze mirror with a phoenix motif of gold and silver inlaid with lacquer, 8th century Technology during the Tang period was built also upon the precedents of the past. Previous advancements in clockworks and timekeeping included the mechanical gear systems of Zhang Heng (78–139) and Ma Jun (), which gave the Tang mathematician, mechanical engineer, astronomer, and monk Yi Xing (683–727) inspiration when he invented the world's first clockwork escapement mechanism in 725. This was used alongside a water clock and waterwheel to power a rotating armillary sphere in representation of astronomical observation. Yi Xing's device also had a mechanically timed bell that was struck automatically every hour, and a drum that was struck automatically every quarter-hour; essentially, a striking clock. Yi Xing's astronomical clock and water-powered armillary sphere became well known throughout the country, since students attempting to pass the imperial examinations by 730 had to write an essay on the device as an exam requirement. However, the most common type of public and palace timekeeping device was the inflow clepsydra. Its design was improved by the Sui dynasty engineers Geng Xun and Yuwen Kai. They provided a steelyard balance that allowed seasonal adjustment in the pressure head of the compensating tank and could then control the rate of flow for different lengths of day and night.