It is true that so early as 1809, Richard Trevethick and Robert Dickenson had proposed to build “large ships with decks, beams, and sides of plate iron,” and had even suggested “masts, yards, and spars” of iron, which latter are now by no means uncommon. “But,” says Lindsay, “as these inventors or patentees did not put their ideas into practice, no other person (if, indeed, any other person gave even a passing thought to the subject) was convinced that any craft beyond a boat or a river-barge could be constructed of iron, much less that if made in the form of a ship, this material would oppose more effectual resistance to the storms of the ocean, or, if dashed upon the strand, to the angry fury of the waves, than timber, however scientifically put together. But though no available substance can withstand the raging elements with less chance of destruction than plates of iron riveted together in the form of a boiler (the principle on which iron ships are now constructed), the public could not then appreciate their superior value; and it was not until 1818 that the first _iron vessel_ was built.” This vessel is in use even now. Three years afterwards a steam-engine was, for the first time, fitted into a vessel built of iron—the _Aaron Manby_—constructed for Mr. Manby and Captain Napier, afterwards Admiral Sir Charles Napier. Gradually the suitableness of these vessels was becoming apparent, and from this time dates the establishment of some of the greatest ship-building yards, like those of the Lairds and Fairbairns. In 1834 the first-named firm built the _Garry Owen_ for service between Limerick and Kilrush. Almost fortunately, she was driven on shore with a number of wooden vessels, all of which were wrecked or seriously damaged, while she got off with scarcely any damage, and the credit of iron vessels became improved. But another of the chief and more tenable objections to the extended use of iron vessels was the perturbation of the compass. This has been clearly shown to proceed almost entirely from the proximity of iron _not_ forming a part of the _hull_ of the ship, the magnetic influence of which is comparatively even all round. A funnel, tank, boilers, the machinery, the iron fastenings even of a deck-house, &c., may all have their influences. Still these influences are now regulated and understood, and iron ships are more commonly employed than those of wood, showing that it is not an objection which can be urged to-day. After the early steamers came by degrees iron sailing vessels, till at length we find iron applied to a grand steamer, magnificent then and first-class still, the _Great Britain_. “Experience by degrees successfully met almost every objection; and science was again triumphant over prejudice and ignorance. Iron had been made not merely to float, but to ride buoyantly over the crest of the wave amid the raging elements.” [Illustration: SECTION AND PLAN OF THE STERN OF A SCREW STEAMER.]