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Other regions of the world, including India and China, also have early evidence of water clocks, but the earliest dates are less certain
Some authors, however, write about water clocks appearing as early as 4000 BC in these regions of the world.
Greek astronomer, Andronicus of Cyrrhus, supervised the construction of the Tower of the Winds in Athens in the 1st century B.C.
The Greek and Roman civilizations are credited for initially advancing water clock design to include complex gearing, which was connected to fanciful automata and also resulted in improved accuracy
These advances were passed on through Byzantium and Islamic times, eventually making their way to Europe
Independently, the Chinese developed their own advanced water clocks（钟）in 725 A.D., passing their ideas on to Korea and Japan.
Automatic clock of al-Jazari, 12th century.
Some water clock designs were developed independently and some knowledge was transferred through the spread of trade
Pre-modern societies do not have the same precise timekeeping requirements that exist in modern industrial societies, where every hour of work or rest is monitored, and work may start or finish at any time regardless of external conditions
Instead, water clocks in ancient societies were used mainly for astrological reasons
These early water clocks were calibrated with a sundial
While never reaching the level of accuracy of a modern timepiece, the water clock was the most accurate and commonly used timekeeping device for millennia, until it was replaced by the more accurate pendulum clock in 17th century Europe.
In 797 (or possibly 801), the Abbasid caliph of Baghdad, Harun al-Rashid, presented Charlemagne with an Asian Elephant named Abul-Abbas together with a "particularly elaborate example" of a water clock.
An elephant clock in a manuscript by Al-Jazari (1206 AD) from The Book of Knowledge of Ingenious Mechanical Devices.
In the 13th century, Al-Jazari, an engineer who worked for Artuqid king of Diyar-Bakr, Nasir al-Din, made numerous clocks of all shapes and sizes
The book described 50 mechanical devices in 6 categories, including water clocks
The most reputed clocks included the Elephant, Scribe and Castle clocks, all of which have been successfully reconstructed
As well as telling the time, these grand clocks were symbols of status, grandeur and wealth of the Urtuq State.
Early mechanical clocks
None of the first clocks survive from 13th century Europe, but various mentions in church records reveal some of the early history of the clock.