Semaphore.

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Semaphore, or optical telegraph, was first invented by an Englishman Robert Hooke. He promoted it in 1684 but was not successful in having it endorsed. More than a hundred years later a Frenchman Claude Chappe, developed the principle and was successful in having it deployed in 556 stations throughout France. Semaphore was transmitted not only by mechanical means of moving flags or wooden arms erected on structures but also by ships to communicate to land with their flags, Aldis Lamps, Heliographs and hand held flags by people on land. The system was limited by weather and darkness, and was not at all private. The average speed to transmit a message was two words per minute. Later, England and Sweden developed a system of shuttered panels and this system was used until 1850.

Semaphore in Tasmania, Australia.

* Governor Macquarie ordered the first signal station in Tasmania, to be erected on Mount Nelson near Hobart in 1811. Signalling by means of flags reported the arrival of ships in the Derwent River. The moveable arm semaphore was in use in England by 1827 and reached Tasmania in 1829. The original three-arm system, incapable of sending numbers greater than 666, was replaced in 1838 with a six-arm system, with 999,999 possible settings. Codebooks listed up to 3000 different signals.

* Source: The Companion to Tasmanian History - Semaphore and Signalling by Bruce Rosen, 2006.

In Tasmania, human as well as shipping movements were tracked by this system. Until 1846, a chain of semaphore stations dotted the Tasmanian Peninsula. Convicts attempting to escape from the fiercely guarded penitentiary at Port Arthur knew the system to their peril. From the strategic heights of Mt Cunningham, Eaglehawk Neck, Mt Raoul and Mt Nelson to Hobart town, messages of their sighting could be transmitted from Hobart to Port Arthur in under 15 minutes.

By the mid nineteenth century the speediest form of communication over short distances in Australia was the semaphore system. Operated widely at capital ports and headlands to announce the sighting of shipping, the semaphore formed a visual telegraph that conveyed messages alphabetically by the positioning of its two arms. However, there were several drawbacks to this optical telegraph's use, despite its historical adoption in peace and war. Rain, fog, mist and snow, dimmed its power. It was labour intensive and totally ineffective at night.

It was the electric telegraph that would transform the business of communication in Australia and bring mercurial speed to the flow of news, information and human exchange that underpinned the structures of a rapidly advancing society.

The Seaside Town of Semaphore, South Australia

Footnote: As a matter of interest, the town of Semaphore in South Australia, was named after the technology. It is located approximately 20 kilometres from the Adelaide CBD and is a contemporary reminder of its historical significance. Semaphore equipment was used there until the 1850's. In 1856, the electric telegraph line was extended from Port Adelaide to Semaphore.

The last commercial semaphore station closed in the year of 1880, in Sweden.

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