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May 26, 1370
King Charles V of France decrees that all Paris churches at the same time as the royal palace help end the ringing of the bell at the Canonical hours decreed by the church.
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May 26, 1400
Mechanical clocks were built in Europe using a main spring and balance wheel.
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Christiaan Huggens invented the first pendulum clock, capable of far greater accuracy than any preceding timekeeper. But the clock foes not work at sea.
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Galileo Galilei realizes that the frequency of the pendulum’s swing depends on it length.
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John Harrison builds a clock that only loses five seconds on a voyage from England to Jamaica.
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Telegraph invented allowing instant transmission of time signals.
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Time ball is dropped in at noon each day in the U.S. Naval Observatory ships in the harbor use the ball to set their clocks.
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Twenty-five countries except Greenwich, England as the prime meridian. The prime meridian becomes the basis for time throughout the world.
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Salespeople for the R.W. Sears Watch Company fan out across America selling affordable timepieces.
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A radio time signal starts being transmitted in Washington DC to help ships find longitude
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Physicist Isador Rabi suggests making a clock based on the study of atoms, using a method called atomic beam magnetic resonance
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National Bureau of standards build the first atomic clock, using ammonia.
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A second is formally defined as 9,192,631,770 vibrations of the cesium atom. For the first time, time is not defined by the movement of astronomical bodies
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Time is more popular than ever, about half-a-billion watches are sold each year.
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Alfred the Great used candles to measure time.
