Editing Water clock (section)

== Designs ==
[[File:1648 Eschinardi.jpg|thumb|Eschinardi's water clock (Reproduced from [[Francesco Eschinardi]], ''Appendix Ad Exodium de Tympano'')]]
A water clock uses the flow of water to measure time. If viscosity is neglected, the physical principle required to study such clocks is [[Torricelli's law]]. Two types of water clock exist: inflow and outflow. In an outflow water clock, a container is filled with water, and the water is drained slowly and evenly out of the container. This container has markings that are used to show the passage of time. As the water leaves the container, an observer can see where the water is level with the lines and tell how much time has passed. An inflow water clock works in basically the same way, except instead of flowing out of the container, the water is filling up the marked container. As the container fills, the observer can see where the water meets the lines and tell how much time has passed.
Some modern timepieces are called "water clocks" but work differently from the ancient ones. Their timekeeping is governed by a [[pendulum]], but they use water for other purposes, such as providing the power needed to drive the clock by using a [[water wheel]] or something similar, or by having water in their displays.

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 [[Automaton|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 wheel]]s, and [[Program (machine)|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]].{{Citation needed|date=November 2011}}

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 a commonly used timekeeping device for millennia, until it was replaced by more accurate [[verge escapement]] mechanical clocks in Europe around 1300.<ref>{{cite journal |last1=Mills |first1=A. A. |title=Newton's Water Clocks and the Fluid Mechanics of Clepsydrae |journal=Notes and Records of the Royal Society of London |date=August 1982 |volume=37 |issue=1 |pages=35–61 |doi=10.1098/rsnr.1982.0004 |jstor=531476 |url=https://www.jstor.org/stable/531476 |access-date=18 June 2024|url-access=subscription }}</ref>