It may be useful to add that the gross tonnage of iron vessels classed during 1882 by the three societies of Lloyd's, the Liverpool Registry, and the Bureau Veritas was 1,142,000, and of steel 143,000 tons, and that the proportion of steel to iron vessels is increasing from year to year. I am informed by our colleague, Mr. Pearce, of Messrs. Elder's firm, that the largest vessel built by them in 1869 was an iron steamer, of 3,063 tons gross, with compound engines of 3,000 horse power, working at 60 lb. pressure; speed, 14 knots.
The largest vessel now on the ways is the Oregon, of 7,400 tons gross, and 13,000 horse power; estimated speed, 18 knots. The superficial area of the largest plates in the former was 22½ square feet; that of the largest plate in the latter is 206 square feet. The Oregon is an iron vessel, but some of the largest vessels now being built by Mr. Pearce's firm are of steel.
The information which I have obtained from Messrs. Thomson, of Glasgow, is especially emphatic as to the supersession of iron by steel in the construction of ships. They say that large steel plates are as cheap as iron ones, and that they have never had one bad plate or angle in steel. This is confirmed by Mr. Denny, who says: "Whenever our shipwrights or smiths have to turn out anything particularly difficult in shape, and on which much 'work' has to be put, they will get hold of a piece of steel if they can."
It will be readily understood that the rolls, the hammers, the machinery for punching, drilling, planing, etc., used in the manufacture and preparation of plates and angles for shipbuilding and armor plates are on a scale far different at the present date from what they were in 1869. Perhaps the most striking examples of powerful machinery for these purposes are the great Creuzot hammer, the falling mass of which has recently been increased to 100 tons, and the new planing machines at the Cyclops Works, which weigh upward of 140 tons each, for planing compound armor plates 19 in. thick and weighing 57 tons.