Portsmouth Time Ball: Where Public Timekeeping Began
Long before radio pips, GPS or the internet, knowing the exact time was a serious matter at sea. One of the world's first modern public time signals - a time ball devised by a Royal Navy officer - was put into action at Portsmouth in 1829. This is the story of that idea, and how TimeInUK carries the same simple purpose into the digital age.
What was a time ball?
A time ball was a large, hollow ball mounted on a tall mast on a prominent building near a harbour. It was raised and then dropped at a precise, pre-arranged moment each day. Anyone within sight - especially a navigator watching through a telescope from a ship - could use the exact instant of the drop to check and correct their clocks. It was, in effect, public infrastructure for sharing accurate time before any electrical signal existed.
Why ships needed accurate time
Finding longitude - your east-west position at sea - depended on knowing the exact time at a fixed reference place, such as Greenwich, and comparing it with local time from the sun. Ships carried a marine chronometer, a precision clock set to that reference time. Because chronometers drift slightly, they had to be rated - checked against a known-accurate signal - before a voyage. A time ball let a whole harbour of ships correct their chronometers at once, simply by watching it fall.
Portsmouth's 1829 time-ball connection
Portsmouth, one of the Royal Navy's most important ports and home to the Royal Naval Academy, is where the idea was first put into action. In 1829 a time ball devised by Captain Robert Wauchope was tested there - widely regarded as the first modern time ball. We describe this carefully as Portsmouth's time-ball connection: the surviving landmark most people visit today is the later Greenwich ball, but the concept that spread around the world was demonstrated on England's south coast first.
Captain Robert Wauchope
The idea came from Robert Wauchope (1788-1862), a Royal Navy captain who later became an admiral. From around 1818 he worked on a way to signal the exact time from a fixed point to ships so their chronometers could be rated, and he set out his plan to the Admiralty. His design - a large ball dropped at an agreed instant each day - was simple, visible from a distance, and needed nothing aboard ship beyond a telescope and a clock.
Greenwich's famous time ball, 1833
Following the Portsmouth demonstration, the most famous time ball of all was installed at the Royal Observatory, Greenwich, in 1833, set up by the Astronomer Royal John Pond. On the roof of Flamsteed House, the bright red ball rises partway at 12:55, fully at 12:58, and drops at exactly 1pm - a routine it still performs today. It became one of the world's best-known public time signals, distributing accurate time to ships on the Thames and to Londoners alike.
From time balls to modern timekeeping
Time balls were the first link in a chain of one-time-for-all public signals. As technology advanced, the visual ball was joined and then overtaken by telegraph time signals, then radio - including the familiar broadcast pips - and finally the satellite and internet time that quietly synchronises our phones and computers today. The technology changed completely; the underlying idea did not.
How TimeInUK continues the idea
TimeInUK exists for the same simple reason the Portsmouth time ball did: to give people accurate UK time, freely and clearly. Instead of a ball dropping over a harbour, it is a live clock in your browser - showing the current UK time, whether we are on GMT or BST, and how UK time compares around the world. Different century, same purpose.
Frequently asked questions
Was Portsmouth's time ball really the first?
It is widely regarded as the first modern time ball, put into action at Portsmouth in 1829 by Captain Robert Wauchope, before the famous Greenwich ball followed in 1833.
Does the Greenwich time ball still work?
Yes - it still drops at 1pm each day at the Royal Observatory, Greenwich.
Why did ships need a time ball?
To set and check their marine chronometers against an accurate reference time, which was essential for working out longitude at sea.