Deal Time Ball & Communication




The objective of this short paper is not to reproduce information that is already on display in the Deal Museum, but to introduce recently discovered evidence in the UK and Australia about the role that Deal played in the development of time signals and communications. Sir George Airy in Greenwich and Sir Charles Todd in Adelaide are central figures in the story. Rather than give a large number of references to archives of the Royal Greenwich Observatory, now held in Cambridge University Library, and records in South Australia, I have noted my own publications that contain the detailed evidence. I have also noted a few papers and books by other authors that contain important historical background. I am particularly indebted to Lesley Abell in Adelaide for her careful exploration of the Todd archive and to my twin brother Michael, who helped to put Deal in perspective.


The man at the centre of time signal provision was the Astronomer Royal, based at the Royal Greenwich Observatory. In an informative brief history, Stuart Malin records how the Observatory developed to the present day (Malin, 1987). It had been founded specifically for the accurate determination of longitude in 1675, with John Flamsteed as the first Astronomer Royal. Flamsteed established that it was possible to develop the “method of lunar distances”, using the position of the moon against the background of stars as a clock. Finally, in 1766, the fifth Astronomer Royal, Neville Maskelyne, published the Nautical Almanac that would enable longitude to be determined in 1767. It was a triumph, but it was a method that tested the most skilled of navigators. Another solution was about to become practicable.

In a remarkable achievement, taking most of his working life, John Harrison was able to produce his compact “H4” timekeeper in 1759, that allowed Greenwich Time to be known accurately on a ship that had been at sea for many weeks (Sobel, 1996). Local time, determined from the sun’s position, then allowed accurate determination of longitude. It was not easy to manufacture accurate, reliable chronometers in the large numbers that would allow them to be carried by all ocean-going vessels and the method of lunar distances remained in use for a long time. The general transition to chronometers actually took until about 1830, the start of the time ball story (Rooney, 2009).

A few seconds of time represents a significant error in longitude. Accurate land-based time signals, visible or audible to nearby ships, were the key to chronometer calibration. The concept of the time ball was developed by Captain Robert Wauchope, RN (Bartky and Dick, 1981). His idea was that a large ball, visible to ships in harbour, would be dropped from a tower at an exact predetermined time each day. This would be published in nautical almanacs, together with the latitude and longitude at the time ball location. Repeat measurements on successive days would allow the chronometer rate to be determined. Among other benefits, this removed the need for delicate chronometers to be moved ashore for calibration, a process that could easily lead to accidental damage. An experimental time ball operated at Portsmouth for the first time in 1829. Wauchope proposed the construction of the first public time ball at Greenwich. His plan was referred to John Pond, the sixth Astronomer Royal, and construction started in August 1833. The Greenwich apparatus was supplied by Maudslay, Sons & Field.



The records of Maudslay, Sons & Field were almost entirely destroyed at the end of the nineteenth century, when the company was liquidated. The only reference to time balls is a list in the handwriting of Charles Sells, who had been Chief Draughtsman at Maudslays for almost the whole of his working life, with the following entries:

Greenwich 1833
Edinburgh 1852
S. Foreland (Deal) 1853
N. S. Wales (Sydney) 1855
C of Good Hope (Siemens) 1873

Although the original intent had been to install the Deal time ball on the South Foreland lighthouse, the then Astronomer Royal, George Biddell Airy, decided that it would be better placed on the old semaphore tower in Deal. It would then be visible to shipping anchored in the Downs, not just passing ships. Airy made reference to Deal in his notes for 1854: “Deal Time-Ball has now been executed by Messrs. Maudslays and Field (sic), and is an admirable specimen of the workmanship of those celebrated engineers”. The 1853 manufacturer’s plate can still be seen at the Deal museum.

The last entry used to be a mystery, but recent research has shown that the 1873 time ball was built for Siemens Brothers, who shipped it to New Zealand, not the Cape. Maudslays undoubtedly built the apparatus for Edinburgh, Deal, and Sydney, NSW between 1852 and 1855 (Kinns and Abell, 2009). The Greenwich apparatus used a chain hoist, but the others used rack and pinion mechanisms. The Sydney apparatus was replicated nineteen years later for Lyttelton, NZ; it was shipped from London by Siemens Brothers in 1874 and was long thought to have been built by that company (Kinns, 2009). Thanks to 1899 correspondence between Sir Charles Todd in Adelaide and Henry Chamberlain Russell, the Government Astronomer in Sydney, we know how the Sydney apparatus was modified by Russell during the 1870s, which helped to confirm that Lyttelton still has the original Sydney design. All have survived, although the time ball at Deal is now operated using a modern apparatus. Deal was unique in this group: the ball was dropped from Greenwich using the railway telegraph system and a return signal was sent automatically to confirm the drop. Apart from Lyttelton, the others were in close proximity to the observatories that controlled them, so visual confirmation was feasible.

The 1833 Greenwich apparatus was operated manually at first, but automatic electric operation was introduced during the 1850s. The 1853 design for Deal was similar to Edinburgh, but included a return signal to Greenwich. The 1855 time ball for Sydney Observatory used a further development of the mechanism, also with automatic electric operation, which was replicated at Lyttelton.


Airy served as the seventh Astronomer Royal from 1835 to 1881. He was in post at the height of time signal provision around the world. His correspondence, now held in the University Library at Cambridge, shows that he had a considerable influence on time signal development. Airy often offered advice to those seeking to provide time signals, but he did not exercise control over the selection of designs or manufacturers, which was left to local initiative and budget constraints. The time ball at Deal was the only one outside Greenwich that was under his direct control. Airy often supplied the Deal drawings to third parties. There were many exchanges of letters about time signals from the 1850s onwards, showing the extent to which they were considered essential for safe navigation worldwide.

The 1898 Admiralty list of time signals for mariners included 94 time balls around the world. There were many more time balls at inland locations, so the total number is likely to have been at least 200. They had a range of accuracy, varying from a fraction of a second at locations like Deal, the Cape of Good Hope and Sydney, where high-quality transit instruments and regulated clocks were used with automatic electric operation, to errors that could be a minute or more. Such large errors were potentially dangerous to navigators. Airy and other leading astronomers were particularly critical of those using private observatories and manual intervention, whose accuracy was unverified. That applied to Glasgow, for example, which only had a time ball from 1858 to 1864 (Kinns, 2010).

Although Portsmouth was the site of the very first time ball, Airy was critical of the Portsmouth time signals. There was protracted correspondence during the 1870s with the naval authorities, who were protective of local observatory facilities and manual operation at Portsmouth when Airy wanted to replicate the Deal system. When asked to provide information about British litoral time signals for the German Ambassador in 1878, he failed to get timely information from Portsmouth. He pointed this out to no less than the Earl of Derby, then Foreign Secretary. This suggests that his relations with the Admiralty tended to be less than cordial. That may have stemmed partly from Airy’s long, but ultimately failed, campaign to establish a time signal at the Start Point, which met with consistent opposition from their Lordships.


Charles Todd had a talent for mathematics which resulted in his employment in 1841, at age fifteen, as a Computer at the Royal Greenwich Observatory, where he helped to collate observational data with other better-educated boys. Anxious for new challenges, Todd persuaded Airy to support his application in 1848 for a post at the University Observatory in Cambridge. In 1854, Todd returned to Greenwich to the Galvanic Department where his task was to maintain the time balls in London and at Deal. This task involved using the new telegraphic equipment to send time signals from Greenwich.

In 1855 when possible candidates for the post of Observer and Superintendent of Telegraphs in South Australia were being considered, Airy was not certain that young Todd could manage the task. Airy tested Todd’s ability by sending him to solve a problem with the time ball at Deal. Todd found a fault with the telegraph signal and corrected it quickly. That proved his ability to Airy, who then sent him to acquaint himself with other mechanisms near London. Todd was offered the South Australian position and he began preparing for a post at the other side of the world.

Charles Todd achieved lasting fame through construction of the telegraph line that linked Adelaide to Darwin and worked for the first time on 22 August 1872. The story of that great task, undertaken at a time when Australia had yet to be crossed from south to north, is told superbly in The Singing Line (Thomson, 1999). There are other twists to the Todd story that stem from his work at Greenwich and Deal. Todd had written before he left for Adelaide in 1855 that he hoped to install a time ball there. He tried to convince his superiors in South Australia to provide the funds and spent many years designing and promoting a system that would be accurate and cheap to make, even making a working model to show how it could be done. It was only after the massive increase in shipping through Adelaide that resulted from completion of the first Anglo-Australian telegraph link from Adelaide to London via Darwin in 1873, that he achieved his aim. It was then his turn to come under pressure to supply the time ball quickly. Semaphore is now thought to have had the first heavy-duty system to be made in Australia. It was almost certainly designed by Todd himself, using his experience with the Greenwich and Deal systems (Abell and Kinns, 2010).

In 1899, Todd corresponded with Russell in Sydney, about a time ball for Perth in Western Australia. Russell told Todd how he had modified the Sydney apparatus, having been critical of some design aspects. Todd responded by saying that he had seen the Sydney apparatus under construction at Maudslays’ works in 1855 and that it was thought to have been a very fine piece of work.


In May 1873, the Board of Trade wrote to Sir George Airy, in response to a request from the Consul General of the German Empire for plans of time balls at Greenwich, Liverpool and Portsmouth. After extensive correspondence, it was agreed that the plans for Deal, which was regarded by Airy as the premier British system of its time, met the German requirements. This is likely to have led to a German design, using similar principles, which was supplied to northern ports in Germany after 1875; a 5 ft. time ball diameter and 10 ft. drop were the favoured parameters in Germany, just like Deal (Kinns, 2009). The detailed design was German, so this is another example of how Deal influenced development, but failed to lead to further orders for Maudslay, Sons & Field.


Abell, Lesley and Kinns, Roger, 2010. ‘Telegraph’ Todd and the Semaphore Time Ball. Accepted for publication in the Journal of the Historical Society of South Australia, November 2010.

Bartky, Ian R. and Dick, Steven J., 1981. The first Time Balls. Journal for the History of Astronomy, 12, 155–164.

Kinns, Roger, 2009. Time-keeping in the Antipodes: a Critical Comparison of the Sydney and Lyttelton Time Balls. Journal of Astronomical History and Heritage, 12, 97-107.

Kinns, Roger, 2010. Glasgow Time Signals: a Source of Friction with Edinburgh. Accepted for publication in the Journal of Astronomical History and Heritage, November 2010.

Kinns, Roger and Abell, Lesley, 2009. The Contribution of Maudslay, Sons & Field to the Development of Time Balls in Australia. International Journal for the History of Engineering & Technology, 79, 59-90.

Malin, Stuart R. C., 1987. The Royal Greenwich Observatory. Yearbook of Science and the Future (published by Encyclopedia Britannica Inc), 247-259.

Sobel, Dava, 1996. Longitude. Published by Fourth Estate, London, 1996), ISBN 1-85702-502-4.

Rooney, David, 2009. ‘John ‘Longitude’ Harrison’, Links (the bulletin of the Newcomen Society), No. 211, September 2009, 8-9.

Thomson, Alice, 1999. The Singing Line (Chatto & Windus, 1999; Vintage 2000 paperback edition), ISBN 0-099-27282-2.

Research by Roger Kinns, communicated by Mike Kinns