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A Water Clock or Clepsydra

Water clocks are some of the oldest time-measuring instruments and were used for millennia until being replaced by pendulum clocks in the 17th century. Water clocks work by regulating the flow of water into or out of a vessel and measuring the amount of time it takes to fill or drain, with some early designs in Babylon and Egypt around the 16th century BC. Over time, designs advanced to include gears, escapement mechanisms, and water wheels, becoming more accurate until comparable to modern timekeeping standards.

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Fionna Bandelaria
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433 views2 pages

A Water Clock or Clepsydra

Water clocks are some of the oldest time-measuring instruments and were used for millennia until being replaced by pendulum clocks in the 17th century. Water clocks work by regulating the flow of water into or out of a vessel and measuring the amount of time it takes to fill or drain, with some early designs in Babylon and Egypt around the 16th century BC. Over time, designs advanced to include gears, escapement mechanisms, and water wheels, becoming more accurate until comparable to modern timekeeping standards.

Uploaded by

Fionna Bandelaria
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as DOCX, PDF, TXT or read online on Scribd
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A water clock or clepsydra (Greek κλεψύδρα from κλέπτειν kleptein, 'to steal'; ὕδωρ hydor, 'water')

is any 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 is then measured.

Water clocks are one of the oldest time-measuring instruments. Where and when they were first
[1]

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. [2]

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 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 [citation

needed]
.

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.

A water clock uses a flow of water to measure time. If viscosity is neglected, the physical principle
required to study such clocks is Torricelli's law. There are two types of water clocks: 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.

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