Tang dynasty water clock timekeepers

Timeline

1. 800–900Bureau of Astronomy, Chang'an · Chang'anIn the late Tang, the Historiography Bureau still announced time by clepsydra standards dividing day and night into a hundred marks; multi-stage clepsydra vessels (such as the distributing, receiving, and leveling vessels) were tended by clepsydra masters, complementing gnomon shadow measurements and providing time standards for calendar revision and court rituals.
2. c. 840–846Chang'an · ShaanxiDuring the Huichang era, the court arranged state sacrifices and administrative rhythms according to clepsydras and the calendar; despite changes in Buddhist policy, astronomical timekeeping agencies maintained routine timekeeping, reflecting the Tang state time order's reliance on clepsydra technology.