Editing Water clock (section)

{{short description|Timepiece in which time is measured by the flow of liquid into or out of a vessel}}
{{For|the individual water clock at The Children's Museum of Indianapolis|Water clock (Indianapolis)}}
[[File:AGMA Clepsydre.jpg|thumb|A display of two outflow water clocks from the Ancient Agora Museum in Athens. The top is an original from the late 5th century BC. The bottom is a reconstruction of a clay original.]]

A '''water clock''', or '''clepsydra''' ({{etymology|grc|''{{wikt-lang|grc|κλεψύδρα}}'' ({{grc-transl|κλεψύδρα}})|[[pipette]], water clock}}; {{etymology||''{{wikt-lang|grc|κλέπτω}}'' ({{grc-transl|κλέπτω}})|to steal||''{{wikt-lang|grc|ὕδωρ}}'' ({{grc-transl|hydor}})|water}}; {{lit| water thief}}), is a [[timepiece]] by which time is measured by the regulated flow of liquid into (inflow type) or out from (outflow type) a vessel, and where the amount of liquid can then be measured.

Water clocks are some of the oldest time-measuring instruments.<ref>{{Harvnb|Turner|1984|p=1}}</ref> The simplest form of water clock, with a bowl-shaped outflow, existed in [[Babylon]], [[Ancient Egypt|Egypt]], and [[History of Iran#Classical antiquity|Persia]] around the 16th century BC. Other regions of the world, including [[History of India|India]] and [[History of China|China]], also provide early evidence of water clocks, but the earliest dates are less certain. Water clocks were used in [[ancient Greece]] and in [[ancient Rome]], as described by technical writers such as [[Ctesibius]] (died 222 BC) and [[Vitruvius]] (died after 15 BC).
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