84 NAVAL SCIENCES. 



D. Iron Ships. 



The increasing use of iron, and the obvious advantages growing out of 

 it, have suggested the idea of constructing iron ships. The first successful 

 experiment was made with river navigation ; but soon iron sea-going vessels 

 were built; and in 1820 the first iron steamship, whose parts were con- 

 structed at Birmingham, made the voyage between England and France. 

 Iron men-of-war are now built 200 feet in length. These vessels possess 

 the advantage of lightness, and also, as the carpentry work is superseded by 

 narrow iron ties, of a greater amount of room ; they moreover last longer 

 without repairing, the one mentioned above having run some thirty years 

 with scarcely any repairs being found necessary. Iron has great advantages 

 for screw propellers, as these must be built very sharp towards the stern for 

 the best effect, and an iron stern-post three inches thick will answer, while 

 one of timber must be at least a foot in breadth. 



In iron ships the keel and ribs are made of iron ; the different parts of the 

 keel are connected with each other and with the stemson and stern by 

 flat bands 15 to 18 inches long, which are strongly riveted together, and 

 joined to the adjacent plates at half their length ; the ribs are curved over 

 iron models of one inch in breadth and a quarter of an inch thick, corres- 

 ponding with the draught-plan ; and then the plates are laid upon them in 

 courses, and bored with holes to match. In vessels of large and medium 

 size the ribs usually consist of two or three pieces, the floor-piece and two 

 top-pieces, which are joined together in the centre of the plates by iron 

 bands. When one of the ribs is so far completed it is fastened to its place 

 on the keel, and temporarily attached to the deck-frame by a band. Each 

 plate is joined to the rib by four rivets, two in the centre and one at each 

 seam. These last it has in common with the adjoining plates. The 

 plating commences as soon as the ribs are connected with each other and 

 with the stemson and stern. The plates are bent into form over a 

 cast-iron model ; they are first heated, and then beaten into shape by 

 large wooden beetles. Up to the water-line the plates are half an inch 

 thick, and above rather lighter ; they lap over each other, and are riveted 

 at the joints. Sometimes, when a degree of elegance in the construction is 

 required, they do not lap over each other, but meet square at the ends, being 

 joined on the inside by iron bands, and in that case they receive a double 

 riveting. The plates are fastened together in the same manner in the length- 

 wise direction of the ship ; they are also sometimes double riveted when they 

 lap over each other, and in that case, according to Fairbairn, are 15 per cent, 

 stronger. The keel-plates and the wale-plates are at least double riveted. 

 The deck is sometimes made of iron plates a quarter of an inch thick; it is 

 thus on the whole more durable, but not so convenient for the crew, as they 

 are apt to slip when there is water on the deck. Iron vessels outlast three or 

 four times those made of timber, provided they are kept in good order and free 

 from rust. The plates between wind and water suffer the most, and must 

 often be painted anew. PL 17, fig. 2, represents the battery of an iron steam 

 propeller, this mode of construction being now applied to men-of-war. 

 V36 



il 



