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14 MARINE REVIEW. [March 27, FLOATING DOCK FOR BERMUDA. A COMPLETE DESCRIPTION OF THE GREAT STRUCTURE WHICH THE BRITISH ADMIRALTY WILL INSTALL ON THE ISLAND. The Review recently published a brief description of the new oe dry dock for Bermuda, but now, through the courtesy of the builders, Messrs. Swan & Hunter, Ltd., Wallsend-on-Tyne, it is enabled to print a far more satisfactory one, illustrated. This new dock, which has been built to the order of the British admiralty, will replace the old oe dry dock that has been stationed at Bermuda since 1869. The old doc is obsolete now, not through age, but through the insufficiency of its dimensions. It is interesting to make a comparison between the dimen- sions of the old and the present docks, for they show. very clearly the great increase that there has been in the size of ships. since the old dock was built. The old dock, like the new, was designed with a view of ac- commodating the largest vessels, then built or building. The length of the old dock was 381 ft. over all, but to obtain its maximum lifting power, gates were fitted which reduced its practical length to 330 ft. Its inside width was 84 ft. between side-walls, and its lifting power was 8,000 tons, which was sufficient for the British ships of the Bellerophon class, to lift which it was specially designed, although it was capable of bringing the keel out of the water of vessels up to 10,200 tons, the then heaviest ships represented by the long fully-rigged line-of-battle ships Agincourt and Minotaur. The present dock is 545 ft. long, and having no gates, the length of the ship it can take is not restricted; its clear width of entrance between rubbing fenders is 100 ft. Its lifting power up to the pontoon deck level is 15,500 tons, but by utilizing the shallow pound this can be increased to 17,500 tons, and the walls are of sufficient height to allow of a vessel drawing 82 ft. to be taken on 3.6-ft. keel blocks. 5 The present dock is of the type known as a floating graving dock, the invention of Messrs. Clark & Standfield, from whose plans it was built. hich i ft. long, is rectangular in shape, but the two terminal EY one have each only 71 ft. of that length rectangular in shape, the remainder being finished off in the form of a blunt-nosed point or bow. The sides of the rectangular portion ol all the pontoons are built up so as to form a broad altar standing 12 ft. above the deck. The side walls which come each side of the pontoons, to which they are attached by double fish plates and tapered pins, taking on to the steel lugs built into the structure both of the wall and pontoon (thus enabling any of the pontoons to be disconnected for the purpose of self-docking) are rectangular structures 435 ft. long by 03.3 ft., ete, high. From their base up to the altar level their width is 13.2 ft., but from here they batter back to the engine deck where their width is 9.1 ft. Where the boilers occur, however, this engine deck is built out at the back to form a chamber 12.6 ft. wide. The walls are pierced with two gangway openings admitting light and air into the interior, and the upper portions or towers are cut down at each end, leaving a flat on which the bollards are placed and the swing bridges, which give access from the top of one wall to that of the other. The ends of the side walls are bevelled off from the back to the same line as that of the pointed portion of the pontoons, thus forming a continuous bow line for the purposes of facilitating the towing. Pontoons of the dock are divided into forty pumping divisions, of which thirty-two are absolutely water-tight and distinct. The side walls have each eight water-tight divisions. All these fifty-six divisions are provided with a separate pipe, each governed by a separate valve. All the pipes in the starboard half of the dock are led directly into the main drain in the starboard wall, and those on the port side into the port wall. These drains are continuous over the whole length of the walls, and the four 18-in, centrifugal pumps in each wall are seated directly on them, so that any one pump can empty all the compartments of its half of dock. Further- more, the central bulkhead dividing the dock into the two halves is not entirely water-tight, but small drainage or leakage holes are left in it, so that even in the event of a complete break-down of the whole of the plant, the other half could still slowly empty the whole dock. THE NEW FLOATING DRY DOCK FOR BERMUDA. Built by Swan & Hunter, Ltd., Wallsend-on-Tyne. This type, of which many examples already exist, notably the large 18,000- ton dock for the United States navy at Algiers, which has just success- fully lifted the battleship Illinois, was specially introduced by that firm with a view of producing a structure having a large amount of longi- tudinal rigidity. The necessity for such rigidity will be apparent when the different types of vessel that the present dock will be called on to lift are remembered. Primarily, it has to lift the line-of-battle ships of 15,000 tons displacement with a length of bearing keel of 343 ft., but in addition it has to deal with cruisers of the Terrible class, of about the same dis- placement but with 383 ft. of bearing keel, and lastly, auxiliary cruisers like the Campania, weighing some 17,000 tons, with a bearing length of keel of 502 ft. It is evident, therefore, that great longitudinal strength is necessary, since whilst the dock has to be long enough to deal with the 600 ft. Campania, practically the whole displacement of the 545 ft., long pontoons have to be utilized to lift a vessel bearing only on some 384 ft. of their length. Apart from this, the fact that the dock in its voyage to Bermuda may have to encounter the long rollers of the Atlantic, also makes it imperative that a very stiff form of structure should be employed, Like the original Bermuda dock, the present one is a self-docking dock, that is, it can lift all parts of itself ott of water, a most necessary facility in the sub-tropical sea of Bermuda. The dock itself consists of five portions, comprising three pontoons which form the main lifting portion of the dock, and two side walls, which, whilst affording a certain amount of lifting power, primarily serve to give the dock stability, and to regulate its descent when the pontoons are subnierged., The center pon- A separate condensing compound engine driving directly on the pump shaft is provided for each pump, and a separate return-tube marine boiler for each pair of engines. The steam pipes are, however, so arranged that either engine can take its steam from either boilers. Each boiler, engine, and pump is, therefore, duplicated in each wall, and further, each wall duplicates the other, so that if only the boiler, engine and pump remain available the dock can stili be lifted. Special provision has been made on the broad altars for the support "of the armor belt of battleships, a stiff channel running along on top 0 them into which the heel of the vertical shores can be stepped, whilst similar channels along the face of the altars receive the raking shores that support the bilges, the shape of the dock at this part resembling fairly closely the stone steps or altars of an ordinary masonry dock. The dock is provided with the usual fittings in the way of strong bollards on the low walls and timber-heads on the top deck, and for warp- ing the vessel into place, six powerful vertical steam capstans are provide with sheaves or fairleads on the edge of the top deck. An electric light installation with its own generating plant is provided in one wall for light- ing all the interior compartments of the dock, and in addition twelve ar¢ lamps are cartied on gallows on top of the towers, which light up when required the whole dock and ship, whilst further mains are led along the dock's sides, from which hand-lamps may be taken off to light up amy particular spot where special work is being carried on. A very useful | fitting for handling weights either on the dock or ship will be found int traveling and swinging electric cranes which run along the whole len