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Ancient Egyptian obelisks are used as shadowclocks to tell time
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Egyptians used the oldest sundial
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Water clocks, or clepsydrae, were used in Ancient Greece.
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The Persians use water clocks to determine the longest and shortest days and to determine holy days.
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Incense clocks are first used in China.
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The earliest mention of candle clocks comes from a Chinese poem, written by You Jianfu.
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China replaces the water in a water clock with mercury for greater accuracy.
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The first geared clock is invented by an Arab engineer named Ibn Khalaf al-Muradi.
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Clock towers are made and used in Western Europe during the Middle Ages.
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The hourglass is used as the first dependable, reusable, accurate, and easily constructed time-measurement device.
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The first wrist watch is gifted to Elizabeth I of England from Robert Dudley
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The Italian Galileo Galile discovers the swing of a pendulum may be used to regulate a clock.
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Huygens and Robert Hooke invented the spiral balance which allows accurate pocket watches to be made.
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Sir Francis Ronalds of London creates the electrostatic clock.
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The first accurate atomic clock is built by Louis Essen in the UK.
