Time-balls

The Greenwich Time-ball As the name implies, a marine time-keeper (chronometer) is designed to keep time at sea. But for navigational purposes it is necessary to know the time in the first place, and the going of the timekeeper must be checked periodically thereafter. Whatever method was used to do this, it was most unwise to move the chronometer so a pocket watch had to be used as an intermediary, or a signal be made from shore. In 1818 Captain Robert Wauchope RN proposed that time-balls should be erected. In 1833 he suggested to the Admiralty that one should be at Greenwich. In October of the same year the following notice to Mariners was issued: The Lord Commissioners of the Admiralty hereby give notice, that a time-ball will henceforth be dropped, every day, from the top of a pole on the Eastern turret of the Royal Observatory at Greenwich, at the moment of one o’clock PM mean solar time. By observing the first instance of its downwards movement, all vessels in the adjacent reaches of the river (Thames) as well as in most of the docks, will thereby have the opportunity of regulating and rating their chronometers. The ball will be hoisted half-way up the pole, at five minutes before One o'clock, as a preparatory signal, and close up at two minutes before One. By command of their Lordships *John Barrow* One o'clock was chosen because at noon the astronomers at the Royal Observatory might be busy finding the time. The apparatus, constructed in 1833 remains substantially unchanged today. Not only did the Greenwich time-ball - said to be the world’s first public time signal - give Greenwich time to ships in London’s river and docks but, for the first time, it made Greenwich time regularly available to those ashore who could see it. The original Greenwich time-ball of 1833 was of wood and painted leather, the present aluminium one dating to 1919. The ball is automatically raised halfway up the mast at 12.55pm, to the top at 12.58pm and drops at 1.00pm precisely, (BST in summer, GMT in winter). Until 1960 the hoisting was done by hand. The Sydney Time-ball The Observatory on Observatory Hill overlooking Sydney Harbour at Sydney, Australia, was founded in 1855 specifically to house the time-ball to provide a time service for the city and harbour. The time-ball system was based on the Greenwich system and the mechanism was built by the same company, Maudsley, son and Field of London. It was inaugurated in 1858, being dropped for the first time on 5 June that year. The ball is still dropped, originally manually but now with the help of an electric motor. Between 1906 and 1942 a one o'clock gun was fired at Fort Denison in Sydney Harbour as the ball dropped. This practice was restarted a few years ago however the time-ball is no longer visible from Fort Denison as the Sydney Opera House obscures the view of the Observatory from the Fort. There are plans to put a remote-controlled camera on the tower which will be accessible to visitors who will not only be able to see the live view but compare it with views made over 100 years ago from the same spot. Another camera will feed images into the World Wide Web through the Powerhouse Museum's Web site.

Some well known Time-balls Around 150 public time-balls are known or reported to have been installed around the world after that at Greenwich in 1833, though few survive and still work. Most were in or near ports, for ships to check their chronometers. Those for other public use often also served purposes of commercial promotion. Hand-hoisted balls were most common, though there were electrical, hydraulic and pneumatic mechanisms. Local master-clocks often provided the dropping signal though some worked directly to 'Greenwich Time' received by electric telegraph. Time-balls were erected in Mauritius, St Helena, Cape of Good Hope, Madras, Bombay and Washington. The restored 1876 time-ball station at Lyttelton, in New Zealand's South Island, now overlooks a modern container port rather than the sailing clippers it first served. The building is one of the few specially designed for the purpose. The hand-hoisting mechanism was built by Siemens, and the ball originally triggered electrically by a master-clock by Edward Dent, both being ordered from London. The Brighton Clock Tower of 1888, donated to the town by a Mr James Willing, was crowned with a 4 ft. time-ball on a 16 ft. mast, and triggered electrically from Greenwich. It still survives but has not been in operation since the mid-1890s when local residents complained about its noisy operation. The pneumatic time-ball at Deal, Kent, was put up in 1854 on top of the former semaphore tower in the old Navy boat and supply yard there. Like that at Greenwich, from which it received a telegraph signal to drop the ball at 1.00pm, it served ships in the great anchorage of the Downs. It operated from 1855 to 1927 and does so again now the tower is a related museum. The 5ft 6in (1.58m) time-ball on top of the Nelson Monument, on Edinburgh's Calton Hill, was installed there by Charles Piazzi Smyth, second Astronomer Royal for Scotland, in 1854. It has always been fully hand-operated by rack-and-pinion mechanism and is still working. The time-ball on the Electric Telegraph Company's offices in the Strand, London, 1852. The facade designed by John Nash, with its 'pepper-pot' towers still survives, immediately opposite Charing Cross Station. From The Illustrated London News, 11 Sept. 1852. The time-ball in Cornhill, London, 1860. From a letterhead of J. French (late Bennett), chronometer maker, on whose premises it stood. Both this and the Strand time-ball were triggered by telegraph signal from Greenwich.

For our suggestions on art and ideas that relate to this artefact, go to Signposts.
To look at discussion surrounding this artefact, go to Crossroads.