Editing Optical telegraph (section)

=====Van Diemen's Land=====
In southern [[Van Diemen's Land|Van Diemens Land]] ([[Tasmania]]) a signalling system to announce the arrival of ships was suggested by Governor-In-Chief [[Lachlan Macquarie]] when he made his first visit in 1811 <ref>{{cite web |title=Maquarie's Journals - Saturday 30th. Novr. 1811.| url=https://www.mq.edu.au/macquarie-archive/journeys/1811/1811a/nov30.html|website=Journeys In Time }}</ref> Initially a simple flag system in 1818 between Mt. Nelson and [[Hobart]], it developed into a system with two revolving arms by 1829, the system was quite crude and the arms were difficult to operate. In 1833 [[Charles O'Hara Booth]] took over command of the [[Port Arthur, Tasmania|Port Arthur]] penal settlement, as an "enthusiast in the art of signalling" <ref>{{cite book |last1=Masters |first1=W.E. |title=The Semaphore Telegraph System of Van Diemen's Land |date=1973 |publisher=Cat & Fiddle Press |isbn=0-85853-009-0 |page=8}}</ref> he saw the value of better communications with the headquarters in Hobart. During his command the semaphore system was extended to include 19 stations on the various mountains and islands between Port Arthur and Hobart. Until 1837 three single rotating arm semaphores were used. Subsequently the network was upgraded to use signal posts with six arms - a pair top, middle and bottom. This enabled the semaphore to send 999 signal codes. Captain George King of the Port Office and Booth together contributed to the code book for the system.<ref>{{cite book |last1=Masters |first1=W.E. |title=The Semaphore Telegraph System of Van Diemen's Land |date=1973 |publisher=Cat & Fiddle Press |isbn=0-85853-009-0 |page=14}}</ref> 
King drew up shipping related codes and Booth added Government, Military and penal station matters. In 1877 Port Arthur was closed and the semaphore was operated for shipping signals only, it was finally replaced with a simple flagstaff after the introduction of the telephone in 1880.

[[File:LowHeadSemaphore.jpg|thumb|left|alt=A restored two-arm semaphore post at Low Head in Tasmania|A restored two-arm semaphore post at Low Head in Tasmania]]

In the north of the state there was a requirement to report on shipping arrivals as they entered the Tamar Estuary, some 55 kilometers from the main port at this time in [[Launceston, Tasmania|Launceston]]. The [[Tamar Valley, Tasmania|Tamar Valley]] Semaphore System was based on a design by Peter Archer Mulgrave.<ref>{{cite book|title=Peter Archer Mulgrave|chapter=Mulgrave, Peter Archer (1778–1847)|chapter-url=https://adb.anu.edu.au/biography/mulgrave-peter-archer-2489|website=Australian Dictionary of Biography|publisher=National Centre of Biography, Australian National University}}</ref> This design used two arms, one with a cross piece at the end. The arms were rotated by ropes, and later chains. The barred arm positions indicated numbers 1 to 6 clockwise from the bottom left and the unbarred arm 7,8,9, STOP and REPEAT.[[File:FanPositions2.png|thumb|right|alt=Fan positions for the Mulgrave design used in the Tamar Valley Semaphore System|The vane positions indicate code numbers.]] A message was sent by sending numbers sequentially to make up a code. As with other systems the code was decoded via a code book. On 1 October 1835 it was announced in the Launceston Advertiser - "...that the signal stations are now complete from Launceston to George Town, and communication may he made, as well as received, from the Windmill Hill to George Town, in a very few minutes, on a clear day".<ref>{{cite web|title=Launceston Advertiser - 1 Oct 1835|url=https://trove.nla.gov.au/newspaper/article/84775296?searchTerm=semaphore# |newspaper=Launceston Advertiser|date = October 1835}}</ref> The system comprised six stations - Launceston Port Office, Windmill Hill, Mt. Direction, Mt.George, George Town Port Office, Low Head lighthouse. The Tamar Valley semaphore telegraph operated for twenty-two and a half years closing on 31 March 1858 after the introduction of the electric telegraph.<ref>{{cite book |last1=Shipp |first1=Wayne |title=The Tamar Valley Semaphore Telegraph |date=2014 |publisher=Low Head Pilot Station Museum |isbn=978-0-646-93206-4 |page=37}}</ref>
In the 1990s the Tamar Valley Signal Station Committee Inc. was formed to restore the system. The works were carried out over several years and the semaphore telegraph was declared complete once more on Sunday 30 September 2001.<ref>{{cite book |last1=Shipp |first1=Wayne |title=The Tamar Valley Semaphore Telegraph |date=2014 |publisher=Low Head Pilot Station Museum |isbn=978-0-646-93206-4 |page=ix}}</ref>