Water clocks, also known as clepsydrae (sg: clepsydra), along with the sundials, are possibly the oldest time-measuring instruments, with the only exceptions being the vertical gnomon and the day counting tally stick. Given their great antiquity, where and when they first existed is not known and perhaps unknowable. The bowl-shaped outflow is the simplest form of a water clock and is known to have existed in Babylon and in Egypt around the 16th century BC. 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 back to Europe. Independently, the Chinese developed their own advanced water clocks（水鐘）in 725 A.D., 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. 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.
Islamic civilization is credited with further advancing the accuracy of clocks with elaborate engineering. 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.
In the 13th century, Al-Jazari, a Kurdish Muslim engineer from Mesopotamia (lived 1136-1206) 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.
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Other articles related to "water clocks, water, clock, water clock, clocks":
... and astronomers were developing more elaborate mechanized water clocks ... For example, some water clocks rang bells and gongs, while others opened doors and windows to show figurines of people, or moved pointers, and dials ... Some of the most elaborate water clocks were designed by Muslim engineers ...
... Water clocks are reported as early as 4000 B.C ... In Europe, water clocks were used from around 1000 A.D ...
... Water clocks, or clepsydrae, were commonly used in Ancient Greece following their introduction by Plato, who also invented a water-based alarm clock ... One account of Plato's alarm clock describes it as depending on the nightly overflow of a vessel containing lead balls, which floated in a columnar vat ... vat held a steadily increasing amount of water, supplied by a cistern ...
... There is also evidence for the use of water clocks in anciet Egypt ... An early Egyptian water clock dating to about 1500 BC was found among other items in the tomb of the pharaoh Amenhotep I their creation is attributed to an inventor named Amenemhat ... Early water clocks were usually bowl-shaped with a small hole at the bottom and markings on the inside at even intervals ...
... In Greece, a water clock was known as a clepsydra (water thief) ... The Greeks considerably advanced the water clock by tackling the problem of the diminishing flow ... Ctesibius invented an indicator system typical for later clocks such as the dial and pointer ...
Famous quotes containing the words clocks and/or water:
“When I woke, the town spoke.
Birds and clocks and cross bells
Dinned aside the coiling crowd,
The reptile profligates in a flame,
Spoilers and pokers of sleep....”
—Dylan Thomas (19141953)
“With a tongue like a razor he will kiss,
the mother, the child,
and we three will color the stars black
in memory of his mother
who kept him chained to the food tree
or turned him on and off like a water faucet....”
—Anne Sexton (19281974)