The oldest remaining building in Battery Point was built in 1818 as a guard house for soldiers of The Mulgrave Battery and later became a signal station relaying messages from Port Arthur via a similar station on top of Mount Nelson. For many years all shipping intelligence and Government, military and penal station messages were transmitted using the navel system of signal flags hoisted on the signal mast at the headquarters station on the site at Prince's Park, above Castray Esplanade.
The semaphore station and its signal mast were constructed above the Mulgrave Battery, allowing communication with ships entering the mouth of the river, and through a relay system of masts, all the way to Port Arthur penitentiary on the Tasman Peninsula. The first type of mechanical semaphore used in Van Diemen's Land in 1829 was a copy of a type then recently invented for shipping intelligence on the west and south coasts of England. This semaphore had two revolving arms, one above the other. Each arm had three positions on one side of the staff, and three on the other, being revolved for that purpose.
The first circuit of stations, and one which lasted until the end of the system, consisted of the stations at Castray Esplanade, Mt. Nelson, Mt. Louis (near Pierson's Pt.), and Mt. Royal (near Three Hut Pt.). From these stations a comprehensive view of shipping movements In Storm Bay, D'Entrecasteaux Channel, and the River Derwent could he obtained. At first, the arms were operated by hemp ropes. These were found to perish and vary in length at different temperatures, so chains, consisting of rods of iron about 2 ft. in length with eyes forged at the end and coupled by hooks, came into use.
With the semaphore, a number of flags and pennants were also used, and while limited in its usefulness, this code was a great improvement on the previously used navel flag code. Two other flags used were the Blue Peter or "get ready" flag and the tri-colour, which was used to signify that the number shown on the arms was a number only and had no reference to the code. In the code book, each letter of the alphabet had its own number. Under each letter were words beginning with that letter, each having its own number.
Grouped under appropriate headings for quick references were also numerous orders, questions, answers, and information of all kinds. Every bay, hill, cliff, river, road, and town had its number, so that it was seldom necessary to spell out a signal. A look-out was kept at all stations from dawn to dusk to take signals from any station in sight. No satisfactory system of night signaling was evolved until the introduction of the Morse lamp code.
In 1833 Capt. Charles O'Hara Booth, of the 21st Fusiliers, was appointed commandant at Port Arthur, and a more efficient type of semaphore was deemed necessary. Capt. Booth set about making an improvement in the locations of semaphores. Accompanying his men into the bush he sought out sites on, hills, cliffs, and other prominent places, changing sites for better ones as occasion required. Capt. Booth found that smoke from bush fires in summertime and sea fogs in winter time made certain sites undesirable, and that change became necessary. The sites chosen for a semaphore was usually a high hill which was cleared of timber growth, leaving one large tree standing wherever possible for construction of the signal mast.
Another circuit of stations consisted of Mt. Nelson, Mt. Augustus (near Pipeclay Lagoon), Mt. Communication (Tasman's Peninsula), and thence to other stations on Tasman's and Forester's Peninsulas, which at one time numbered 21 or more. The military posts spread out around the country side also sometimes had temporary semaphore posts but these were not considered part of the regular system. The only safe guide as to the positions of regular semaphore stations are the code books, some of which are still in existence.
The old signal station building at Princes Park is a lasting memory of early communications from the early years of the colony and has been really beautifully preserved in it’s original position and setting. Well worth checking it out.
Main Information Source
Trove Website (Digitized newspapers - The Mercury 9/1/1940)