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Time ball

Time ball is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Time ball rather than just read about it. In short: A time ball is a large, wooden or metal ball that moves up and down a pole, and which is dropped at a predetermined time of day. Because precise timekeeping is essential to the determination of longitude at sea, time balls were principally erected to allow navigators aboard nearby ships to synchronize their marine chronometers with a reference time standard controlling the ball.

Time ball — main illustration
Time ball — illustration

Key takeaways

  • Time ball belongs to science; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Time ball to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Time ball from memory before moving on to harder problems.

Reference excerpt

A time ball is a large, wooden or metal ball that moves up and down a pole, and which is dropped at a predetermined time of day. Because precise timekeeping is essential to the determination of longitude at sea, time balls were principally erected to allow navigators aboard nearby ships to synchronize their marine chronometers with a reference time standard controlling the ball. Time balls have been rendered obsolete by electronic time signals, but some are kept in operation as tourist attractions.

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, 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 modern time ball was erected at Portsmouth, England, in 1829 by its inventor Robert Wauchope, a captain in the Royal Navy. Others followed in the major ports of the United Kingdom (including Liverpool) and around the maritime world. One was installed in 1833 at the Greenwich Observatory in London by the Astronomer Royal, John Pond, originally to enable tall ships in the Thames to set their marine chronometers, and the time ball has dropped at 1 p.m. every day since then. Wauchope submitted his scheme to American and French ambassadors when they visited England. The United States Naval Observatory was established in Washington, D.C., and the first American time ball went into service in 1845. 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. With the commencement of radio time signals (in Britain from 1924), time balls gradually became obsolete and many were demolished in the 1920s. A contemporary version of the concept has been used since 31 December 1907 at New York City's Times Square as part of its New Year's Eve celebrations; at 11:59 p.m., a lit ball descends from a pole on the roof of One Times Square over the course of 60 seconds, reaching its conclusion at 12:00 a.m. The spectacle—which has given rise to many similar events—was inspired by an employee of The New York Times having seen the time ball on the Western Union Building in operation.

Around the world Over sixty time balls remain standing, though many are no longer operational. Existing time balls include:

Australia

The Old Windmill, Brisbane, Queensland Fremantle, Western Australia Sydney Observatory, New South Wales Newcastle Customs House, New South Wales Semaphore, South Australia Williamstown Lighthouse, Victoria Geelong Telegraph Station, Victoria

Canada Citadelle of Quebec, Quebec City no longer true. Clearly seen from the river and aligned on the meridian for observation purposes, Building 20, also known as the Ball House, is the former observatory and time ball tower.

New Zealand

In March 1864 New Zealand's first time ball was established at Wellington. This was followed by Port Chalmers in June 1867, Wanganui in October 1874, Lyttelton in December 1876 and Timaru in 1888. Attempts were made by some people in Auckland to establish time balls there from 1864 onwards, but these were not recognized by the authorities until a permanent time ball was mounted on the Ferry Building in August 1901.

Port Chalmers: Established by the Otago Provincial Council on top of Observation Point in Port Chalmers in June 1867 the time ball service initially operated at 1 pm on all days of the week except Sundays. The service was discontinued in October 1877, but following concerns raised by 11 shipmasters the service resumed in April 1882 as a weekly service. In 1910 the time keeping service was discontinued but the ball however continued to be used until 1931 as a warning device. It was removed in 1970 but a replacement was restored to service in 2020. Lyttelton: Established in December 1876 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, and a decision was made in March 2011 to dismantle the building, a danger to the public, but the tower collapsed during the major aftershock that hit the Lyttelton area on 13 June 2011. In November 2012, a large financial donation 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. The station was officially reopened on 2 November 2018.

Wellington:The Wellington time ball service started in March 1864. It received its time information from the Dominion Observatory which was also communicated to the Lyttelton time ball service. Dunedin used local observatory facilities. Wellington had two time ball sites – the time ball was erected at the first site by mid-January 1864 on top of the Custom House building on the Wellington waterfront and later relocated in 1888 to the J Shed Woolstore on top of the accumulator tower. This building and the time ball burnt down on 9 March 1909. Instead of replacing the Wellington time ball after the second site burnt down, time light signals were introduced at the Dominion Observatory. The earliest record of this was 22 February 1912. They were in use until 1937 when wireless signals took over as the new way to keep time.

Poland Gdańsk, Poland (The time ball was installed in 1876, moved to the Danzig (now Gdańsk) lighthouse in 1894, and removed in 1929. In 2008 it was reconstructed from original plans)

South Africa Victoria & Alfred Waterfront, Cape Town

… excerpt ends here. Continue reading the full article.

Illustrations

Time ball: A time ball, installed in 1833, atop the Octagon Room at the Royal Observatory, Greenwich, London
A time ball, installed in 1833, atop the Octagon Room at the Royal Observatory, Greenwich, London
Time ball: The Boston Time Ball (1881)
The Boston Time Ball (1881)
Time ball: Sydney Observatory with time ball
Sydney Observatory with time ball
Time ball: The time ball at Port Lyttelton, New Zealand, started signalling Greenwich Mean Time to ships in the harbour beginning in 1876. The Lyttelton Timeball Station was destroyed by an earthquake in 2011 but was rebuilt and reopened in 2018.[8]
The time ball at Port Lyttelton, New Zealand, started signalling Greenwich Mean Time to ships in the harbour beginning in 1876. The Lyttelton Timeball Station was destroyed by an earthquake in 2011 but was rebuilt and reopened in 2018.[8]
Time ball: J Shed, Wellington Woolstore, showing the Time Ball at its second site c. 1900
J Shed, Wellington Woolstore, showing the Time Ball at its second site c. 1900

Worked examples

Example 1 — a first encounter with Time ball

Start with the simplest possible case. Write down what Time ball claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Time ball before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Time ball ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Time ball

In research
Time ball appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Time ball in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Time ball is common in secondary-school and first-year university syllabi. It links to neighbouring topics Horology, Navigational equipment, Time balls, so understanding it makes those chapters shorter.
In everyday life
Look for Time ball outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Time ball in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Time ball means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Time ball out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Time ball in simple terms?

A time ball is a large, wooden or metal ball that moves up and down a pole, and which is dropped at a predetermined time of day. Because precise timekeeping is essential to the determination of longitude at sea, time balls were principally erected to allow navigators aboard nearby ships to synchron…

Why does Time ball matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Time ball?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Time ball.

Tags

  • Horology
  • Navigational equipment
  • Time balls

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