A water clock or clepsydra (Greek κλέπτειν kleptein, 'to steal'; ὕδωρ hudor, 'water') is any timepiece in which time is measured by the regulated flow of liquid into (inflow type) or out from (outflow type) a vessel where the amount is then measured.
Water clocks, along with sundials, are likely to be the oldest time-measuring instruments, with the only exceptions being the vertical gnomon and the day-counting tally stick. Where and when they were first invented is not known, and given their great antiquity it may never be. 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, claim that water clocks appeared in China as early as 4000 BC.
The Greeks and Romans further 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.
Other articles related to "water clock, water clocks, clocks, clock, water":
... Only a few modern water clocks exist today ... In 1979, French scientist Bernard Gitton began creating his Time-Flow Clocks, which are a modern-day approach to the historical version ... throughout the world, including one at Europa-Center's The Clock of Flowing Time in Berlin, one at The Children's Museum of Indianapolis in Indianapolis, Indiana, and the Shopping Iguatemi in Porto Alegre ...
... mechanism of a washstand automaton with those as employed in (water) clocks ... Another early clock to use escapements was built during the 7th century in Chang'an, by Tantric monk and mathematician, Yi Xing, and government official Liang Lingzan ... An astronomical instrument that served as a clock, it was discussed in a contemporary text as follows was made in the image of the round heavens and on it ...
... Self-striking water clocks had already been invented by the Arabians and the Chinese (in 1091), and a more primitive form was in use by the Koreans ... Although it is believed, Samguk Sagi records that an office overseeing the use of water clocks had been established during the Three Kingdoms Period ... The Korean version consisted of two stacked jars of water, with water dropping from the top to the bottom at a measured rate ...
... The Borugak Jagyeongnu ("Water Clock of Borugak Pavilion"), classified as a scientific instrument, is the 229th National Treasure of South Korea and was designated by the South Korean government on March 3, 1985 ... The water clock is currently held and managed by the Royal Museum in Seoul ... Water clocks have a long history of use in Korea with the first mention of one in the records of the Samguk Sagi during the Three Kingdoms era ...
... to describe the square-pallet chain pump used to lift water (and other substances) ... Their primary use was for lifting water into irrigation ditches, but chain pumps were also used in public works programs, such as when Zhang Rang (d. 189 CE) had an engineer build several of them to lift water into pipes that provided the capital Luoyang and its palaces with clean water ...
Famous quotes containing the words clock and/or water:
“We are hardly ever grateful for a fine clock or watch when it goes right, and we pay attention to it only when it falters, for then we are caught by surprise. It ought to be the other way about.”
—Philip Dormer Stanhope, 4th Earl Chesterfield (16941773)
“Over the water come
Children from homes and childrens parks
Who speak on a finger and thumb,
And the masked, headless boy.”
—Dylan Thomas (19141953)