Editing Optical telegraph (section)

====British empire====
=====Ireland=====
In Ireland R.L. Edgeworth was to develop an optical telegraph based on a triangle pointer, measuring up to 16 feet in height. Following several years promoting his system, he was to get admiralty approval and engaged in its construction during 1803–1804. The completed system ran from Dublin to Galway and was to act as a rapid warning system in case of French invasion of the west coast of Ireland. Despite its success in operation, the receding threat of French invasion was to see the system disestablished in 1804.<ref>Adrian James Kirwan, 'R.L. Edgeworth and Optical Telegraphy in Ireland, c. 1790-1805' in Proceedings of the Royal Irish Academy (2017). https://www.jstor.org/stable/10.3318/priac.2017.117.02?seq=1#page_scan_tab_contents</ref>

=====Canada=====
In Canada, [[Prince Edward, Duke of Kent and Strathearn|Prince Edward, Duke of Kent]] established the first semaphore line in North America. In operation by 1800, it ran between the city of [[City of Halifax|Halifax]] and the town of [[Annapolis Royal|Annapolis]] in [[Nova Scotia]], and across the [[Bay of Fundy]] to [[Saint John, New Brunswick|Saint John]] and [[Fredericton]] in [[New Brunswick]]. In addition to providing information on approaching ships, the Duke used the system to relay military commands, especially as they related to troop discipline. The Duke had envisioned the line reaching as far as the British garrison at [[Quebec City]], but the many hills and coastal fog meant the towers needed to be placed relatively close together to ensure visibility. The labour needed to build and continually man so many stations taxed the already stretched-thin British military and there is doubt the New Brunswick line was ever in operation. With the exception of the towers around Halifax harbour, the system was abandoned shortly after the Duke's departure in August 1800.<ref>{{Citation|last=Raddall|first=Thomas H.|title=Warden of the North|publisher=McClelland and Stewart Limited|place=Toronto, Canada|year=1971|url=http://www.ourroots.ca/toc.aspx?id=6183&amp;qryID=8cbb8294-7361-4fdc-ac50-78627a229b5f}}</ref><ref>{{Citation|last=Rens|first=Jean-Guy|title=The invisible empire: A history of the telecommunications industry in Canada|publisher=McGill-Queen's University Press|place=Montreal, Canada|year=2001|isbn=9780773520523|url=https://books.google.com/books?id=8kUmt-Q7ySMC&pg=PA7 }}</ref>

=====Malta=====
[[File:Sudika Nadur Ta' Kenuna.jpg|thumb|left|[[Ta' Kenuna Tower]], a semaphore tower in [[Nadur]], [[Gozo]], Malta, built by the British in 1848]]
The British military authorities began to consider installing a semaphore line in [[Malta]] in the early 1840s. Initially, it was planned that semaphore stations be established on the bell towers and domes of the island's churches, but the religious authorities rejected the proposal. Due to this, in 1848 new semaphore towers were constructed at [[Għargħur Semaphore Tower|Għargħur]] and [[Għaxaq Semaphore Tower|Għaxaq]] on the main island, and another was built at [[Ta' Kenuna Tower|Ta' Kenuna]] on Gozo. Further stations were established at the [[Grandmaster's Palace (Valletta)|Governor's Palace]], [[Selmun Palace]] and the [[Giordan Lighthouse]]. Each station was staffed by the [[Royal Engineers]].<ref>{{cite web|title=Semaphore Tower|url=http://gharghur.gov.mt/semaphore-tower/|website=Għargħur Local Council|archive-url=https://web.archive.org/web/20160304094408/http://gharghur.gov.mt/semaphore-tower/|archive-date=4 March 2016}}</ref>

=====India=====
[[File:Semaphore Tower at Khatirbazar, Andul.jpg|thumb|upright|The Semaphore Tower at Khatirbazar, Andul in Howrah district of West Bengal]]

In India, semaphore towers were introduced in 1810. A series of towers were built between [[Fort William, India|Fort William]], [[Kolkata]] to [[Chunar Fort]] near [[Varanasi]].The towers in the plains were {{cvt|75 – 80|ft}} tall and those in the hills were {{cvt|40 – 50|ft}} tall, and were built at an interval of about {{cvt|13|km}}.<ref>{{cite news |last1=Singh |first1=Gurvinder |title=Towering messengers of a bygone era |url=https://www.thehindubusinessline.com/blink/know/towering-messengers-of-a-bygone-era/article23923909.ece |access-date=31 March 2019 |issue=Business Line |date=18 May 2018}}</ref>

=====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>