It will be observed, from what has been said, that the idea of a screw propeller is a very old one. Watt, Bramah, Trevethick, and many more, had given descriptions of the screw. Trevethick schemed a number of its forms and applications, which have been the subject of many subsequent patents. It has been so with many inventions. It is not the man who gives the first idea of a machine who is entitled to the merit of its introduction, or the man who repeats the idea, and re-repeats it, but the man who is so deeply impressed with the importance of the discovery, that he insists upon its adoption, will take no denial, and at the risk of fame and fortune, pushes through all opposition, and is determined that what he thinks he has discovered shall not perish for want of a fair trial. And that this was the case with the practical introducer of the screw propeller will be obvious from the following statement. Francis Pettit Smith was born at Hythe, in the county of Kent, in 1808. His father was postmaster of the town, and a person of much zeal and integrity. The boy was sent to school at Ashford, and there received a fair amount of education, under the Rev. Alexander Power. Young Smith displayed no special characteristic except a passion for constructing models of boats. When he reached manhood, he adopted the business of a grazing farmer on Romney Marsh. He afterwards removed to Hendon, north of London, where he had plenty of water on which to try his model boats. The reservoir of the Old Welsh Harp was close at hand--a place famous for its water-birds and wild fowl. Smith made many models of boats, his experiments extending over many years. In 1834, he constructed a boat propelled by a wooden screw driven by a spring, the performance of which was thought extraordinary. Where he had got his original idea is not known. It was floating about in many minds, and was no special secret. Smith, however, arrived at the conclusion that his method of propelling steam vessels by means of a screw was much superior to paddles--at that time exclusively employed. In the following year, 1835, he constructed a superior model, with which he performed a number of experiments at Hendon. In May 1836, he took out a patent for propelling vessels by means of a screw revolving beneath the water at the stern. He then openly exhibited his invention at the Adelaide Gallery in London. Sir John Barrow, Secretary to the Admiralty, inspected the model, and was much impressed by its action. During the time it was publicly exhibited, an offer was made to purchase the invention for the Pacha of Egypt; but the offer was declined.