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  2. History of timekeeping devices - Wikipedia

    en.wikipedia.org/wiki/History_of_timekeeping_devices

    The most accurate pendulum clocks were controlled electrically. [166] The Shortt–Synchronome clock, an electrical driven pendulum clock designed in 1921, was the first clock to be a more accurate timekeeper than the Earth itself. [167] A succession of innovations and discoveries led to the invention of the modern quartz timer.

  3. Pendulum clock - Wikipedia

    en.wikipedia.org/wiki/Pendulum_clock

    Pendulum clock conceived by Galileo Galilei around 1637. The earliest known pendulum clock design, it was never completed. Vienna regulator style pendulum wall clock. A pendulum clock is a clock that uses a pendulum, a swinging weight, as its timekeeping element. The advantage of a pendulum for timekeeping is that it is an approximate harmonic ...

  4. Atomic clock - Wikipedia

    en.wikipedia.org/wiki/Atomic_clock

    The most accurate caesium clocks based on the caesium frequency of 9.19 GHz have an accuracy between 10 −15 –10 −16. Unfortunately, they are big and only available in large metrology labs and not useful for factories or industrial environments that would use an atomic clock for GPS accuracy but cannot afford to build a whole metrology ...

  5. Clock of the Long Now - Wikipedia

    en.wikipedia.org/wiki/Clock_of_the_Long_Now

    Clock of the Long Now. The Clock of the Long Now, also called the 10,000-year clock, is a mechanical clock under construction that is designed to keep time for 10,000 years. It is being built by the Long Now Foundation. A two-meter prototype is on display at the Science Museum in London.

  6. Grandfather clock - Wikipedia

    en.wikipedia.org/wiki/Grandfather_clock

    Grandfather clock. 8-day longcase clock. This example dates back to 1700 and the case to late 19th – early 20th century. The original dial of this clock was replaced by a brass dial with Tamil numerals, perhaps around the same time as the case. The original long-case was also replaced by a mandapa -shaped wooden carved case done in South ...

  7. International Atomic Time - Wikipedia

    en.wikipedia.org/wiki/International_Atomic_Time

    International Atomic Time. International Atomic Time (abbreviated TAI, from its French name temps atomique international[1]) is a high-precision atomic coordinate time standard based on the notional passage of proper time on Earth's geoid. [2] TAI is a weighted average of the time kept by over 450 atomic clocks in over 80 national laboratories ...

  8. List of atomic clocks - Wikipedia

    en.wikipedia.org/wiki/List_of_atomic_clocks

    Department of Defense master clock. United States Naval Observatory. Washington, D.C. United States. 18 cesium atomic clocks and 4 hydrogen maser clocks. Cs, H. National Institute of Information and Communications Technology. Koganei, Japan [ 13 ] Optical lattice clock.

  9. Universal Time - Wikipedia

    en.wikipedia.org/wiki/Universal_Time

    Universal Time. Universal Time (UT or UT1) is a time standard based on Earth's rotation. [1] While originally it was mean solar time at 0° longitude, precise measurements of the Sun are difficult. Therefore, UT1 is computed from a measure of the Earth's angle with respect to the International Celestial Reference Frame (ICRF), called the Earth ...