The Semaphore Chain

In 1795 the navy decided to construct an optical telegraph system using a chain of signaling stations to enable the Admiralty in Whitehall to communicate with the naval base at Portsmouth on the south coast. At first a shutter technique devised by Sir George Murray was used but in 1822 the link was upgraded by Captain Sir Home Riggs Popham who chose semaphore instead.

Messages could be sent over the 108km path in about 15 minutes. The information superhighway of its age was in operation until about 1847 when the electric telegraph superseded it. The only surviving station now open to the public is at Chatley Heath in Surrey.

There were 15 nodes:

1. Admiralty
2. Chelsea
3. Putney Heath
4. Coombe Warren
5. Esher
6. Chatley Heath
7. Guildford
8. Witley
9. Haslemere
10. Woolbeding
11. Marden
12. Compton
13. Portsdown Hill
14. Eastney
15. Portsmouth High St.

I often visit Web sites which are linked by telegraph - "Shuks, Elmer, I got another o' them JPEGs for ya, an' my sendin' arm is tuckered out."

Dead tree:

1. Holzmann and Pehrson, "The Early History of Data Networks", IEEE press, 1995, ISBN 0-8186-6782-6
2. Holmes, Thomas W.,"The Semaphore", Stockwell, 1983, ISBN 0 7223 1629-1
3. Wilson, Geoffrey, "The Old Telegraphs", Phillimore & Co. Ltd., 1976, ISBN 0 900592 79 6

Sir Home Riggs Popham held one of two naval careers which were drawn upon by C.S.Forester in creating his fictional hero Horatio Hornblower.

In war, he preferred guile to gore, and captured more ships by this means than most captains ever did by force.

John D. Grainger, History Today, October 1999

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E-mail:R.Clarke@surrey.ac.uk
Last modified: 2007 November 25th.