Who invented the time-ball?

Press, 16 April 1982, Page 14

Who invented the time-ball?

Recent historical research by two astronomers in Washington, D.C., has uncovered evidence that the first time-ball, the precursor of that at Lyttelton and seaports all over the world, was actually in use at least three years earlier than generally supposed. They have also found that the inventor to whom credit is due for the device was a somewhat eccentric captain in the Royal Navy, Robert Wauchope, who erected the first crude time-ball in 1829.

By

DUNCAN STEEL,

of the

physics department of the University of Canterbury

In the nineteenth century, accurate knowledge of the local time was an important piece of information to any ship’s captain. Although it was -easy to ascertain the latitude of his vessel by observing the altitude of any known star above the horizon with a sextant or similar instrument, measuring his longitude was much more difficult.

. In theory, the position of the sun in the sky (or the time of sunrise or sunset) could give the navigator the local time, and hence the longitude — but only if he also knew the correct time at the origin of longitude, the Greenwich meridian — what we now call “Greenwich Mean Time.”

However, until the 1760 s there was no clock suitable for use on board a ship, because the vessel’s pitching and rolling disrupted the swinging of a pendulum; in fact, James Cook made his first voyage without the advantage of a chronometer. In these days ignorance of longitude was as deadly an enemy of the sailor as scurvy.

By the time Cook left on his second expedition, however, the problem had been partially solved. In response to a £20,000 prize offered by the British Government, an English watchmaker, John Harrison, had devised a reasonably accurate shipboard clock (although he was forced to wait 30 years for his reward!). Despite this advance, the complete’ solution was not yet at hand. Although clocks of this type lost or gained only a few seconds every day, over a long voyage an accumulated error of one minute of time would lead to a miscalulation of the ship’s position of up to 15 nautical miles.

The remedy was to provide in each port a source of the correct local time so that the rate of loss or gain shown by the chronometers aboard each ship could be calibrated, and the vessel’s officers could then make due allowance for the error during the next leg of their journey. In the next port of call, the clock would again be reset.

The question was, what would be the most efficient way to supply the correct time to all of the boats in a harbour? Various methods were tried in different' parts of the globe, such as physically taking the chronometers to the town’s astronomical observatory, if it had one. The instant at which a star of known position in the sky was in transit (passing directly overhead) gave them the local time, and this could be ascertained by the observatory’s instruments. Obviously, this was timeconsuming, inefficient, and risky to the clocks; the port officials required a way of remotely signalling the time to all of the ships. A number of techniques were experimented with, such as the firing of a pistol or a cannon; and many other suggestions (some outrageous) were put forward. The erection of a time-ball at the Royal Greenwich Observatory in 1833, whereby a large black ball is dropped at a pre-arranged instant, led to the adoption of this method throughout, the

world. However, the two United States astronomers have now shown that the Greenwich device was itself modelled upon an earlier version.

v lan R. Bartky and Steven J. Dick work at the National Bureau of Standards and the United States Naval Observatory, respectively. (The latter institution is probably well known to most New Zealanders because of the recent furor over the proposed Black Birch Observatory near Blenheim.) The 6 air were sifting through the r nited States National Archives, when they came upon a number of letters from Captain Wauchope to the Secretary of the United States Navy.

These letters showed that Wauchope had built and tested a time-ball in 1829 at the dockyards in Portsmouth, England — hence predating the Greenwich time-ball of 1833. Realising the importance of this find, Bartky and Dick delved deeper into the story, and have now presented their findings in the “Journal for the History of Astronomy,” a scholarly periodical published in England.

Until the present it had generally been accepted that the time-ball idea originated in 1824, with the first working example, that at Greenwich, coming nine years later. However, the two Americans have unearthed the fact that in 1836 Wauchope wrote to the editors of the “Nautical Magazine,” claiming priority for himself and producing evidence that he first thought of the idea in 1818. This claim has lain unnoticed for almost a century and a half, as has Wauchope’s description of his experiments at Portsmouth, while others have been credited with the invention. The truth seems to be as follows. After entering the Royal Naval Academy at Portsmouth in 1802, Robert Wauchope served against the French in the early part of the century. Gradually rising through the ranks from lieutenant to captain, he died an admiral in 1862.

His career might have been even more noteworthy if it had not been for the restrictions of his devout religious practices. The sailors of the vessels he commanded thought him prudish because he refused to allow them to bring prostitutes on board. For many years he patrolled the far-flung waters of the South Atlantic, the “Cape and St Helena Station,” and it was there in 1818, as commander of the Eurydice, that he conceived of the time-ball as an aid to navigation. Wauchope let his idea lie dormant until 1829 when he built the prototype device at Portsmouth. The results were altogether favourable, the ball being dropped at noon upon a-signal from the Portsmouth Observatory. Significantly, Wauchope suggested that the standard time for the drop should be adopted as 1 p.m., so that the observatory staff responsible for supplying the signal to the time-ball operators would be able to check their

own clock by observing the transit of the sun at noon. Indeed, this was the nominal drop-time used by most future time-ball- stations, including . that at Lyttelton after its completion in 1876. (For reasons that are unclear, the Lyttelton signal was altered to 3.30 p.m. after the end of the First World War. The daily signal at this time continued until the utility of the time-ball was superseded by radio signals in 1934). Wauchope’s next step was to urge the Admiralty in London to set up a permanent time-ball station at Greenwich, where the ball could be seen by ships lying on the Thames. The facility was duly opened and supervised by the Astronomer Royal, John Pond. After Pond’s retirement in 1835 his replacement in this post, Sir George Biddell Airy, zestfully pursued the cause of the navigators, trying to supply an accurate time signal in as many ports as possible. Because of this Airy has been widely regarded as the “father of the time-ball,” to the neglect of Wauchope. In the meantime Wauchope was presenting his plans to the French and American ambassadors in London, urging them to adopt the scheme in their own ports. It was a letter to the Secretary of the Navy in Washington regarding this that Bartky and Dick discovered in the National Archives. after it had gathered dust for so long. Wauchope had left the navy in 1819, rejoining the service in 1834. He was again posted to the south Atlantic, in command of the Thalia. By the time that he arrived in St Helena in that year, a time-ball had been erected on the island based upon his original design. (There is evidence to suggest that this also predated the Greenwich installation.) In 1835, another time-ball was built in South Africa, at the instigation of Sir Thomas Maclear, His Majesty’s Astronomer at the Cape. There was another prominent astronomer observing at the Cape in the 1830 s: Sir John Herschel, the son of Sir William Herschel, who discovered the planet Uranus in 1781. Robert Wauchope and John Herschel (this was before his knighthood) became great friends, as, did their wives; in fact, the Wauchopes stood as godparents to Herschel’s son Alexander Stewart, who was born at. the Cape. The boy' went on to become the third generation of astronomer in the Herschel family, and an expert on meteors. Unlike the hollow zinc ball at Lyttelton which has weathered the century since it was made in splendid fashion, the original Greenwich ball was fabricated’ of leather with a wooden frame. It blew down in a gale in 1855 and took two months to repair.

Airy tried to keep the time of ball-dropping precise to within, a fraction of a second, and in this respect had the confidence of sea-captains — but not of the general public. Two inhabitants of Greenwich, a Henry Shaw and a

Joseph Peters, wrote to Airy to explain they had a wager that over a whole year the average time of the drop was closer to noon than 1 p.m. — “this bet is to be the sum of Five Guineas, which said amount is to be spent at the Victoria, Westminster Bridge Road.” The sturdiness of the Lyttelton time-ball station has left it one of a handful in the world still intact and in working order. Its history is detailed in a booklet published by the New Zealand

Historic Places Trust in 1979, ■; after the completion of its ’ restoration by the Lyttelton Maritime Association and the Trust. With the identification ,of, ■' Robert Wauchope as the in- ■ ventor of the time-ball < concept, the final piece in the puzzle of the Lyttelton • station’s history falls into ” place. ... Footnote: The Lyttelton ; Time-Ball Station is open to ’ the public daily, except ■ Christmas Day and Good Friday, from 10 a.m. to 12 noon and 1 p.m. to 4 p.m.