Time ball

From Wikipedia, the free encyclopedia
Jump to: navigation, search
The timeball at Greenwich Observatory, London, is shown in the top right of picture.
The Port Lyttelton, New Zealand, timeball started signaling Greenwich mean time to ships in the harbour beginning in 1876.[1]

A time ball is an obsolete time signalling device. It consists of a large, painted wooden or metal ball that is dropped at a predetermined time, principally to enable navigators to verify their marine chronometers from their ships offshore. Accurate timekeeping is one means by which longitude can be determined at sea.

Although the use of time balls has been replaced by electronic time signals, some time balls have remained operational as historical tourist attractions.

History[edit]

Time ball stations set their clocks according to transit observations of the positions of the sun and stars. Originally they either had to be stationed at the observatory itself, or had to keep a very accurate clock at the station which was set manually to observatory time. Following the introduction of the electric telegraph around 1850, time balls could be located at a distance from their source of mean time and operated remotely.

The first time ball was erected at Portsmouth, England in 1829 by its inventor Robert Wauchope, a Captain in the Royal Navy.[2] Others followed in the major ports of the United Kingdom (including Liverpool) and around the maritime world.[2] One was installed in 1833 at the Greenwich Observatory by Astronomer Royal John Pond, and the time ball has dropped at 1 p.m. every day since then.[3] Wauchope submitted his scheme to American and French ambassadors when they visited England.[2] The US Naval Observatory was established in Washington D.C. and the first American time ball went into service in 1845.[2]

Time balls are usually dropped at 1 p.m. (although in the USA they were dropped at noon). They were raised half way about 5 minutes earlier to alert the ships, then with 2–3 minutes to go they were raised the whole way. The time was recorded when the ball began descending, not when it reached the bottom.[4]

With the commencement of radio time signals (in Britain from 1924), time-balls gradually became obsolete and many were demolished in the 1920s.[5]

Lyttelton Timeball Station[edit]

The Lyttelton Timeball Station in Lyttelton, New Zealand was operational until it received partial damage in the 2010 Canterbury earthquake. Further severe damage occurred in the February 2011 Christchurch earthquake[6] and a decision was made in March 2011 to dismantle the building due to the danger it posed to the public.[7] The tower collapsed during the major aftershock which hit the Lyttelton area on 13 June 2011.[8] In November 2012 a large financial donation [9] was made available to contribute towards rebuilding the tower and is being considered by the community. On 25 May 2013 it was announced that the tower and ball would be restored, and that funds were to be sought from the community to rebuild the rest of the station.[10][11]

Times Square[edit]

A modern variation on the time ball has been used since 1908 for New Year's Eve celebrations at New York City's Times Square, where a lit crystal ball located on a pole atop One Times Square is lowered to signal midnight and the arrival of the new year. Unlike a typical time ball, where the beginning of its descent is used as the time signal, the ball begins to be lowered one minute prior at 11:59 p.m., completing its descent at the bottom of the pole at midnight. For 1988, the event's organizers acknowledged the addition of a leap second at midnight by extending the drop to 61 seconds (however, leap seconds are appended worldwide at midnight UTC, which is five hours before midnight in New York.)[12][13]

Around the world[edit]

Today there are over sixty time balls standing, though many of these are no longer operational. The existing stations include those at:


See also[edit]

References[edit]

  1. ^ "Lyttelton Timeball Station, Christchurch". Yahoo! Travel. 
  2. ^ a b c d Aubin, David (2010). The Heavens on Earth: Observatories and Astronomy in Nineteenth-Century Science and Culture. Durham, N.C.: Duke University Press. p. 164. ISBN 978-0-8223-4640-1. 
  3. ^ Greenwich Time Ball Retrieved December 27, 2010
  4. ^ "Deal Timeball Tower: The Ball Drop". Retrieved 4 January 2009. 
  5. ^ a b "The Gdańsk Nowy Port Lighthouse and Time Ball". Archived from the original on 2013-04-01. Retrieved 4 January 2009. 
  6. ^ "New Zealand quake: The epicentre town". BBC News. 25 February 2011. 
  7. ^ Gates, Charlie (4 March 2010). "Timeball Station to be demolished". stuff.co.nz. Retrieved 15 June 2011. 
  8. ^ Greenhill, Marc (14 June 2011-updated). "Workmen unscathed as Timeball Station collapses". stuff.co.nz. Retrieved 15 June 2011. 
  9. ^ Greenhill, Marc (28 November 2012). "Donor fronts to save Lyttelton Timeball Station". Stuff. stuff.co.nz. Retrieved 2012-11-28. 
  10. ^ Lee, Francesca (25 May 2013). "Million dollar donation to rebuild Lyttelton Timeball". Stuff. stuff.co.nz. Retrieved 2013-05-25. 
  11. ^ "$1m donation to rebuild timeball". Radio New Zealand. radionz.co.nz. 25 May 2013. Retrieved 2013-05-25. 
  12. ^ McFadden, Robert D. (1987-12-31). "'88 Countdown: 3, 2, 1, Leap Second, 0". New York Times. Retrieved 2 January 2009. 
  13. ^ "NYC ball drop goes 'green' on 100th anniversary". CNN. December 31, 2007. Retrieved 2007-12-31. 
  14. ^ "Heritage Gateway Listed Buildings Online — Clock Tower and Attached Railings, North Street (north side), Brighton, Brighton and Hove, East Sussex". Heritage Gateway website. Heritage Gateway (English Heritage, Institute of Historic Building Conservation and ALGAO:England). 2006. Retrieved 2 June 2010. 

External links[edit]