Dropping The Time Ball

The journey from ship to shore was a steep one for mariners arriving in the Firth of Forth in the 1840s. To set their chronometers, they had to climb to the transit house, until Royal Astronomer, Charles Piazzi Smyth, suggested a time ball be set up on the turret of the Nelson Monument.

Like his predecessor, Thomas Henderson, who had died two years previously, Piazzi Smyth arrived in Edinburgh from the Cape Observatory in South Africa. His main priority was to work alongside Alexander Wallace (employed as assistant observer since the observatory opened in 1818) to complete the six year programme already set up by Henderson – they did, one year ahead of schedule.

But Piazzi Smyth’s legacy to Edinburgh is far more specific than that. As assistant astronomer at the Cape, he had been responsible for operating the observatory’s time ball. When the ball dropped, the signal enabled navigators to set their chronometers to the correct time without having to come ashore.

Piazzi Smyth 3 (Copy)Receiving the approval of the authorities, the astronomer approached Frederick James Ritchie who had a workshop at 25 Leith Street to assist him with the project. An expert on electric clocks, the horologist adapted the observatory’s master clock to send an electric signal to the lifting mechanism. The signal released the holding pins allowing the time ball to slide down the mast.

Although the time ball had proved to be a success since it officially came into operation in 1852, the black painted ball could not be seen in misty weather or when the smoke from the city’s chimneys was too dense. To solve the problem the Edinburgh Chamber of Commerce suggested that an audible signal be added. Working with Fred Ritchie, the astronomer came up with an ambitious plan to connect the time ball electrically to one of the garrison guns at Edinburgh Castle.

To ensure that the gun fired bang on time, the horologist designed an electric clock which fired the gun automatically when a weight attached to the mechanism dropped at one. Set up by a squad of merchant seamen in three days, the 4,000 foot wire connecting the two clocks hung over the city in a giant arc. Although the time gun failed to fire on the first two days, the eighteen pounder fired on 7th June 1861, providing an audible time check with the time ball which continues to this day.

On a personal note, Charles’ somewhat exotic-sounding name came about from his parents. He was the son of Annarella Smyth, the daughter of a British diplomat, and Commander William Henry Smyth, an officer in the Royal Navy. Born in Naples in 1819, Charles was named after his father’s friend, Giuseppe Piazzi, the Italian astronomer. Professor Piazzi Smyth married his fiancé Jessica Duncan in 1855. An amateur geologist, Jessie was in a position to advise and accompany him on his various projects, including a scientific expedition to the mountains of Tenerife the following year.

For more information, go to: www.piazzi.uk and www.1oclockgun.org.uk

George Robinson’s earlier feature on Thomas Henderson can be found at www.lothianlife.co.uk/2016/04/earth-to-the-stars/


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