THE “VIGILANT.”
From a Photograph. By permission of the Mersey Docks and Harbour Board.
The introduction of electricity and the invention of the telegraph caused a new sphere of work for the steamship. For connecting land to land across the sea, cables had to be laid, and for this purpose it was thought at one time that any very large steamship would suffice. It will be recollected that the unhappy Great Eastern was thus employed after she had given up running as an Atlantic passenger ship. Then presently it was shown to be advisable to use specially designed ships for this purpose. [The illustration facing page 244] shows an interesting little model of one of the older craft thus employed, the telegraph steamer Monarch, a schooner-rigged, iron, screw vessel built at Port Glasgow in 1883, for the Telegraph Department of the Post Office. Enormous sheaves are fitted at the bows as fair-leads for the cable to run out or for hauling it in. This particular ship was employed both in laying and repairing submarine cables, and could carry enough fuel and stores for six weeks’ work. She had a displacement of 2,135 tons, and a single propeller driven by compound engines. The bow-sheave will be easily discerned. An earlier telegraph ship was the Medway, launched in 1865, and built originally for the Mediterranean trade, but she was used in the following year to help the Great Eastern in laying the Atlantic cable. She carried the Newfoundland end of the cable after the Great Eastern had gone as near in to shore as she dared. The Medway also carried 500 miles of cable in case the 2,730 miles which the Great Eastern had aboard should prove inadequate. Another converted vessel, the John Bowes, was used in laying the cable from Dover to Ostend, but modern telegraph ships have the dimensions and general appearance of liners. The Silvertown, which was well-known on this work, is still afloat and to be seen in the West India Dock, London. Such modern cable-laying ships as the Faraday are further supplied with platforms which project from the side of the ship at the stern for greater convenience in the work for which these vessels are intended. As much as from three to four thousand sea-miles of telegraph cable can be carried by some of these ships, which, in addition to the bow fair-lead have a similar arrangement at the stern, and are supplied with all necessary grappling apparatus in case a broken cable has to be picked up.
THE TELEGRAPH STEAMER “MONARCH.”
From the Model in the Victoria and Albert Museum.
DECK VIEW OF THE TELEGRAPH SHIP “FARADAY.”
From a Photograph. By permission of Messrs. Siemens & Co.
Another special type of steamship is the oil-tanker. Owing to the nature of her cargo a steamship that carries oil is far more liable to disaster through combustion than even a cotton-ship. Oil is carried not in barrels, but in bulk. At one time it used to be carried by sailing ships in barrels, but this meant that a great deal of trouble and space were unnecessarily expended. The first tank steamer was built in 1886 by Sir W. G. Armstrong, Mitchell and Company. Carrying a cargo of petroleum in bulk is obviously a fairly risky proceeding. Firstly, there is the terrible risk of fire, more especially as the ship must have engines and furnaces; but there is also the risk of the oil obtaining a good deal of impetus, unless guarded against, as the ship rolls. It can easily be understood that so considerable a weight moving about in liquid form—a shifting cargo, in fact, of a peculiar type—is likely to cause the gravest anxiety. [The illustration facing page 246] will show to what trouble the designers and builders have been put in order to devise a safe oil-carrier. This represents the interior of a modern tank steamer built by Messrs. Sir W. G. Armstrong, Whitworth and Company, Limited, by whose courtesy this photograph of a model is here reproduced. First of all, it will be seen that the whole of the engines are placed aft, so as to be away from the dangerous oil. This characteristic, however, has recently been departed from, and in some ships the engines have been placed amidships, as in most steamships. Of this we might instance the s.s. Phœbus, built by Messrs. David J. Dunlop and Company, for the carrying of 9,000 tons of bulk oil. In such cases as these it is essential to insert a long, oil-tight tunnel which encloses the propeller shaft, but the drawback is that it takes up a good deal of valuable space from the ship’s hold. [The accompanying illustration] shows the holds divided up into a number of separate compartments by means of oil-tight bulkheads, which are further subdivided by a longitudinal bulkhead. But oil possesses the properties of expansion and varies according to the prevailing temperature. It is obvious, therefore, that room must be left for expansion. To meet this, then, a long trunk or slit is left to allow the oil to expand, so that after the ship has filled her holds to the proper height the cargo may yet be allowed to become larger in bulk. The model before us shows slits at the sides at the ’tween deck, so that this expansion may take place. It will be recognised where the ladders lead down to the holds beneath. These vessels carry powerful pumps, the oil being taken on board and discharged by this means. Oil is also employed as the ship’s fuel, and the boiler is kept as far away from the cargo as possible, but in order to counteract the possibility of the oil getting adrift and leaking into the after part of the ship, a separate small compartment is also added, so as more completely to divide the hold from the boiler and engines. This will be easily recognised in the illustration. The other illustration [facing page 246] shows a model of the Silverlip, also with her engines placed well aft; but this, with her derricks and her deck-houses, represents a larger and more complex ship.