102 THE SEA. 



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 Manly 

 constructed for Mr. Manby and Captain Napier, afterwards Admii-al 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 183-1 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." 



Then came the introduction of the screw-propeller, which, if we are to believe some 

 authorities, is an early invention of the Chinese. There have been many claims to its 

 invention in modern times. In May, 1804, Mr. J. Stevens, of the United States, put to 

 sea with a steam-boat propelled with some form of screw. Trevethick, the engineer, in 

 1815, patented "a worm or screw revolving in a cylinder at the head, sides, or stern ot 

 a vessel;" and the following year, Robert Kinder applied for a patent for a shaft and screw 

 almost of exactly the form now in use. The French claim it, and only a few years since 

 erected at Boulogne a monument to Frederic Sauvage, as its inventor. On the front is a 

 bronze bas-relief showing a vessel with a screw-propeller. Sauvage's life was similar to those 

 of many other inventors, in that he spent his days and fortune in perfecting inventions 

 which brought him no profit. Having lost his own money, and got into great difficulties, 

 he was thrown into a debtors' prison, and subsequently ended his days in a madhouse. 

 Lindsay remarks properly that " the number of claimants to every important invention is 

 remarkable. An impartial student will, however, probably come to the conclusion that the 

 invention of the screw and its application was, like that of the steam-engine itself, the sole 

 property of no one man." The time for its development and proper use had come, and 

 many scientific students were inquiring concerning its value. 



There can be little doubt that the first demonstration in our country of its value on 

 a proper scale and in convincing form, was that made by Captain John Ericsson, a Swedish 

 engineer resident in London. After a successful experiment with a model, he had a boat 



