The _Garry Owen_, built in 1834 by MacGregor, Laird and Co. of iron, was only 125 feet in length, 21 feet 6 inches beam, with two engines totalling 90 horse-power. There were no Lloyd’s rules as to scantlings for iron steamers in those days, and builders put in as much material as they thought necessary for the strength of the vessel, which usually meant a liberal allowance. The _Garry Owen_ was not much to look at, but she was very strongly built, a circumstance which had a great deal to do with the development of iron steam-ship building. She nearly came to grief on her first voyage, for she was overtaken by a violent storm, which drove her and several other vessels ashore. These others were of wood. Some of them were soon pounded to pieces by the heavy seas, and those that escaped total loss were badly damaged; but the _Garry Owen_, though bumped and dented somewhat, was able to get afloat again little the worse and return under her own steam. If a steamer strongly built of iron could survive a storm and stranding which ended the careers of several wooden ships of larger dimensions, it was admitted that there was no valid reason why other iron vessels should not prove equally safe, especially if they were larger. It was considered that iron steamers might find useful employment in short voyages, and several were built. One of the chief of these vessels was the _Rainbow_, launched in 1837 for the London and coastal trade. She was 185 feet long by 25 feet beam, and of 600 tons, with engines of 180 horse-power. The use of iron in construction was not the only factor in the tremendous change which was coming in shipbuilding. A new form of propulsion was necessary, and it was found in the screw propeller. Before considering this, however, the development in the construction of paddle-wheels and of the engines designed for paddle-boats may be noticed.