The Rev Dodgson said:

roughbarked said:

roughbarked said:

Water powered geared clocks. :)

Which led me to:
A water clock is one of the oldest instruments ever, and one of the most important. https://en.wikipedia.org/wiki/Water_clock

The Greeks and Romans advanced water clock design to include the inflow clepsydra with an early feedback system, gearing, and escapement mechanism, which were connected to fanciful automata and resulted in improved accuracy. Further advances were made in Byzantium, Syria, and Mesopotamia, where increasingly accurate water clocks incorporated complex segmental and epicyclic gearing, water wheels, and programmability, advances which eventually made their way to Europe. Independently, the Chinese developed their own advanced water clocks, incorporating gears, escapement mechanisms, and water wheels, passing their ideas on to Korea and Japan.

Some water clock designs were developed independently, and some knowledge was transferred through the spread of trade. These early water clocks were calibrated with a sundial. While never reaching a level of accuracy comparable to today’s standards of timekeeping, the water clock was the most accurate and commonly used timekeeping device for millennia, until it was replaced by more accurate pendulum clocks in 17th-century Europe.

“Independently, the Chinese developed …”

I wonder if it was really independent?

How can they be so sure?

I was thinking that too, considering there was considerable trade between the Greeks, the Romans and China.