“MYSTERY” TOWER.

Hawera Star, Volume XLVI, 30 July 1927, Page 9

“MYSTERY” TOWER.

BUILT AS A SUBMARINE TRAP. TXTEREST has revived in the famous “Shoreham mystery ships”—one of the World War secrets, states the London correspondent of the “New York Times.” The “mystery ships” were begun in 1918, but only two were completed—too late to be of use in the war. One of these ships, or towers, is now in plgce off Rpithcnd, where it is doing duty as a lighthouse, replacing the once famous “Nab Lightship.” The other tower, constructed at a cost of over a million pounds and never used, was recently scrapped in Shoreham Harbour. The towers were intended to be towed out into the Channel and sunk there, linked together with strong steel mesh nets, as a protection against German submarines. The programme of construction called for sixteen of them. They were, beyond doubt, weird craft. They took the form of gigantic cones, rising tier by tier like wedding ' cakes of steel and concrete, to a height of 18(>" feet. The base, and all save the top tier were of concrete" blocks, honeycombed to withstand external pressure, and * hollow. Each block was provided with a watertight door, through which water or liquid concrete could be pumped in order to sink the tower; and their equipment included suction pumps by .which the water could be sucked out , again and replaced with air, in order to refloat the tower. Concrete was to <be filled into the blocks only when the tower was in the correct position, for naturally it could not be removed. The tower that has become a lighthouse has been permanently sunk. - ■ The possibility' of using water for this sinking operation was what induced the Admiralty of at least two of the mystery towers, when the original necessity for them was ended by the Armistice. It was then believed that they could be used for salvaging merchantmen sunk by submarines. The idea was that the towers could be towed to the scene of a wreck and sunk, one on each side of the hulk, with the upper tiers above water. Divers would then descend and anchor the hulk securely to the two towers, which could then be filled with air and refloated, bringing up the ship with them. It was an ingenious idea, but never put into practice.

The superstructure of the mystery ships is of steel weighing about 1000 tens. The 100,000 eonerete blocks in the lower structure weigh another 9000 tons. Yet the rowers were so eonstruetjed that when afloat their total draught was only fourteen feet, thus leaving ■ more than 170 feet of structure above water when the blocks were empty. On the steel superstructure was a sort or emergency (leek-, from which the pipes to fill and empty the hull were to be controlled. Inside the steel “surmounting tower” were six decks, containing accommodation for a crew of ninety men. In the centre of these decks was an electric generating plant to supply power for the suction contrivances and for the huge searchlights, which, with the wireless and the electric crane, occupied the flat top deck. The “mystery ships’’ had no motive power of their own and needed -the services of several tugs. They were designed by a Scottish engineer named Menzies, and the execution of his designs was entrusted to TT. A. Clift, a Canadian.