Clocks & timekeeping

Royal Observatory Greenwich holds a treasure trove of some of history's most iconic timepieces. Discover the stories behind John Harrison's groundbreaking marine chronometer H1, Charles Shepherd's 'master clock', and the famous Greenwich Time Ball. Plus, find out about the history of timekeeping and its importance to society.


How do you know that your watch, clock or phone is telling exactly the right time? At one time, the only way was to look to the roof of the Observatory.


Next time someone asks you the time, you may enquire if they want to know the atomic, universal, civil, local, solar or sidereal time…

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While days and years are (fairly) neat astronomical events, what explains months, weeks, hours and minutes?

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Marking the end of British Summer Time, the clocks go back in October, giving us an extra hour in bed. But why do the clocks change?

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See this slave clock connected to the Shepherd master clock yourself to the left of the gate at the Royal Observatory.


How can a dolphin tell the time to the nearest minute?

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In 1967, the world changed and time became a matter of atoms rather than stars.

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On the centenary of Daylight Saving in Britain, Curator of Horology, Rory McEvoy looks back at its history.


Our collection focuses on three key areas: precision marine timekeeping for navigators, precision timekeeping for astronomers and the broader area of domestic timekeeping and time distribution.

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Who was John Harrison, and how did his clocks help to solve the problem of finding longitude at sea?