Many instances have occurred in which water-tight bulkheads have saved life and cargo. One of our largest paddle-steatners, in March, 1857, struck an iceberg with such force as would have shivered a wooden ship (or a badly-built iron one) to pieces. As it was, extensive damage to the forefoot caused the fore compartment to fill with water, but so little did it affect the duration of the voyage, that the passengers were unconscious of anything beyond the concussiou; nor did the public ever hear of anything beyond the shock, as the next voyage was performed without thorough repair.
In the Great Eastern, not only has a complete system of water-tight compartments been carefully arranged, but these have been tudinally crossed by fore and aft bulkheads, in such a manner neither one nor several perforations of her bottom would disable her ; and, in addition to these, a considerable portion of her is doubled, so that the outer skin of plates, separated above two feet from a complete water-tight inner bottom, renders her not only the safest, but the strongest ship in the world; for these two separate bottoms are so broal and stayed, and the whole is so contrived, that her construction may be called cellular or tubular. She is a ship perfect on Scott Russell's wave principle [Snie-13cusliso], with /20 feet of midship portion, the sides of which are perfectly parallel; but with this portion the lines of the stem and stern portions are so gracefully combined, that her form is considered the finest afloat.
It is difficult for nomnautieal persons to comprehend the disparity in size between the Great Eastern and all that preceded her. The best mode of comparing her with other vessels is by noticing that the engine-room of the Great Eastern occupies a cubic space of 5571 tons. Now the Duke of Wellington, a splendid three-decker of 121 guns, is of 3826 tons. Not only, therefore, would the Duke of Wellington stow in the Great Eastern's engine-room, but there would remain surplus space for one of our fine frigates—say, for example, the Orestes, of 1702 tons; and as regards the remaining portions of the Great Eastern, she could, in addition, stow away H.M. ships Waterloo, of 91 guns, with the Goliath, 31eance, and Vanguard, each of 80 guns.
And again, whereas the Great Western carried 600 tons of coal as fuel, the Himalaya 1000 tons, and the Golden Age 1200 tons, the Great Eastern carries 10,000 tons. And further, the Great Eastern, when
immersed to her load water-line, requires 95 tons to be placed on board her in order to sink her one inch deeper, while the Persia requires only 30.
The great inducement for increasing the size of merchant ships, and which has del in particular to the building of the Great Eastern, is that large ships alone are fit to carry fuel sufficient for a long voyage; coal, when supplied at intermediate stations, being often much aug mented, perhaps quadrupled, in cost.
It would bo impossible to enter upon the merits of various kinds of vessels now afloat, a large number of which are either fitted with screw or paddle ; but we remark that so many vessels are now built of iron, that it has been thought necessary by the committee of Lloyd's, London, to keep a cheek upon their mode of construction, in defence of the interests of underwriters, by instituting a few regulations as to the dimensions of the framing, plates, &c., of iron vessels. As an example, no vessel of 3000 tons, built of iron, is allowed to have a keel, stem, or stern-post less than 12 inches by 34. The upright ribs, which correspond with "timbers" in the wooden ships, must be 18 inches apart, and bo formed of angle iron of 6,1 in. x 4 x 13. The thickness of plates for garboard strokes to stand as A I for six years, 13 in. ; for nine years. 1 in. ; for twelve years, 1 in. Plates between garboard strakea and bilge and the aheer-strakes, for six years, j, in. ; for nine years, It in.; and for twelve years, 1 in. Thickness of plates for beams, t in. ; for bulkheads, Angle iron for beam and stringers, or keelsons, al in. x x Thickness of wood for upper decks, &c., 4 in. ; while even the sizes of the rivets are determined in proportion to the thick ness of plates: as an example, fin. plates must have rivets at least in diameter ; in. plates, I in. ; pin. plates, 11 in.; and 1 in. plates, I in. thick. So important an item of the building of an iron ship has the use of rivets been found to be, that very elaborate experiments were in 1557 undertaken by the committee of Lloyds, under the direction of their surveyor, Mr. Mumford, to discover a system of joining iron plates by iron rivets which, while they secured sufficient strength, had no tendency to facilitate the rusting of the plates at the rivet-holes.