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Time ball

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Title: Time ball  
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Subject: Royal Observatory, Greenwich, Titanic Memorial (New York City), Times Square Ball, Time signal, Williamstown, Victoria
Collection: Horology, Navigational Equipment, Time Balls
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Time ball

The time ball at Greenwich Observatory, London, is shown in the top right of picture.
The time ball at Port Lyttelton, New Zealand, started signalling Greenwich mean time to ships in the harbour beginning in 1876.[1]

A time ball or timeball 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 aboard ships offshore to verify the setting of their marine chronometers. Accurate timekeeping is essential to the determination of longitude 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Although the use of time balls has been replaced by electronic time signals, some time balls have remained operational as historical tourist attractions.

Contents

  • History 1
  • Lyttelton Timeball Station 2
  • Times Square 3
  • Around the world 4
  • See also 5
  • References 6
  • External links 7

History

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 the 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 were usually dropped at 1 p.m. (although in the United States 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

The Lyttelton Timeball Station in Lyttelton, New Zealand, was operational until it was damaged 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, a danger to the public,[7] but the tower collapsed during the major aftershock that 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, a project the community considered. 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

A modern variation is the leap second by extending the drop to 61 seconds (although in fact the leap second was five hours earlier, as they occur worldwide at midnight UTC).[12][13]

Around the world

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


See also

References

  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.  
  3. ^ Greenwich Time Ball Retrieved 27 December 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".  
  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"'".  
  13. ^ "NYC ball drop goes 'green' on 100th anniversary". CNN. 31 December 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 ( 

External links

  • "List of Timeballs". Index to the House Documents, Otherwise Publ. as Executive Documents. U.S. Congress. 1876–1877. pp. 305–308.  List of time balls worldwide in 1876.
  • Time ball/cannon hobbyist
  • Time ball and cannon Association
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