page_title: Optical telegraph
section_title: United Kingdom
hierarchical_section_title: Optical telegraph / United Kingdom
caption_attribution_description: English: A diagram of the six shutter telegraph invented by Lord George Murray in 1795, and used by the British Admiralty to communicate from London to the English coast from then until 1816. For more about this system, see http://en.wikipedia.org/wiki/Semaphore_line#U.K. and it's references.
context_page_description: An optical telegraph is a line of stations, typically towers, for the purpose of conveying textual information by means of visual signals. There are two main types of such systems; the semaphore telegraph which uses pivoted indicator arms and conveys information according to the direction the indicators point, and the shutter telegraph which uses panels that can be rotated to block or pass the light from the sky behind to convey information.
  The most widely used system was invented in 1792 in France by Claude Chappe, and was popular in the late eighteenth to early nineteenth centuries. This system is often referred to as semaphore without qualification. Lines of relay towers with a semaphore rig at the top were built within line of sight of each other, at separations of 5–20 miles. Operators at each tower would watch the neighboring tower through a telescope, and when the semaphore arms began to move spelling out a message, they would pass the message on to the next tower. This system was much faster than post riders for conveying a message over long distances, and also had cheaper long-term operating costs, once constructed.
context_section_description: In Ireland, Richard Lovell Edgeworth returned to his earlier work in 1794, and proposed a telegraph there to warn against an anticipated French invasion; however, the proposal was not implemented. Lord George Murray, stimulated by reports of the Chappe semaphore, proposed a system of visual telegraphy to the British Admiralty in 1795. He employed rectangular framework towers with six five-foot-high octagonal shutters on horizontal axes that flipped between horizontal and vertical positions to signal. The Rev. Mr Gamble also proposed two distinct five-element systems in 1795: one using five shutters, and one using five ten-foot poles. The British Admiralty accepted Murray's system in September 1795, and the first system was the 15 site chain from London to Deal. Messages passed from London to Deal in about sixty seconds, and sixty-five sites were in use by 1808.
  Chains of Murray's shutter telegraph stations were built along the following routes: London–Deal and Sheerness, London–Great Yarmouth, and London–Portsmouth and Plymouth. The shutter stations were temporary wooden huts, and at the conclusion of the Napoleonic wars they were no longer necessary, and were closed down by the Admiralty in March 1816.
  Following the Battle of Trafalgar, the news was transmitted to London by frigate to Falmouth, from where the captain took the dispatches to London by coach along what became known as the Trafalgar Way; the journey took 38 hours. This delay prompted the Admiralty to investigate further.
  A replacement semaphore system was sought, and of the many ideas and devices put forward the Admiralty chose the simpler semaphore system invented by Sir Home Popham. A Popham semaphore was a single fixed vertical 30 foot pole, with two movable 8 foot arms attached to the pole by horizontal pivots at their ends, one arm at the top of the pole, and the other arm at the middle of the pole. The signals of the Popham semaphore were found to be much more visible than those of the Murray shutter telegraph. Popham's 2-arm semaphore was modeled after the 3-arm Depillon French semaphore. An experimental semaphore line between the Admiralty and Chatham was installed in July 1816, and its success helped to confirm the choice.
  Subsequently, the Admiralty decided to establish a permanent link to Portsmouth and built a chain of semaphore stations. Work started in December 1820 with Popham's equipment replaced with another two-arm system invented by Charles Pasley. Each of the arms of Pasley's system could take on one of eight positions and it thus had more codepoints than Popham's. In good conditions messages were sent from London to Portsmouth in less than eight minutes. The line was operational from 1822 until 1847, when the railway and electric telegraph provided a better means of communication. The semaphore line did not use the same locations as the shutter chain, but followed almost the same route with 15 stations: Admiralty (London), Chelsea Royal Hospital, Putney Heath, Coombe Warren, Coopers Hill, Chatley Heath, Pewley Hill, Bannicle Hill, Haste Hill (Haslemere), Holder Hill, (Midhurst), Beacon Hill, Compton Down, Camp Down, Lumps Fort (Southsea), and Portsmouth Dockyard. The semaphore tower at Chatley Heath, which replaced the Netley Heath station of the shutter telegraph, is currently being restored by the Landmark Trust as self-catering holiday accommodation. There will be public access on certain days when the restoration is complete.
  The Board of the Port of Liverpool obtained a Private Act of Parliament to construct a chain of Popham optical semaphore stations from Liverpool to Holyhead in 1825. The system was designed and part-owned by Barnard L. Watson, a reserve marine officer, and came into service in 1827. The line is possibly the only example of an optical telegraph built entirely for commercial purposes. It was used so that observers at Holyhead could report incoming ships to the Port of Liverpool and trading could begin in the cargo being carried before the ship docked. The line was kept in operation until 1860 when a railway line 
caption: Diagram of UK Murray six-shutter system, with shutter 6 in the horizontal position, and shutters 1-5 vertical
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