In nearly all seagoing vessels, the Paddle has now almost entirely given place to the Screw. It was long before this invention was perfected and brought into general use. It was not the production of one man, but of several generations of mechanical inventors. A perfected invention does not burst forth from the brain like a poetic thought or a fine resolve. It has to be initiated, laboured over, and pursued in the face of disappointments, difficulties, and discouragements.

Sometimes the idea is born in one generation, followed out in the next, and perhaps perfected in the third. In an age of progress, one invention merely paves the way for another. What was the wonder of yesterday, becomes the common and unnoticed thing of to-day.

The first idea of the screw was thrown out by James Watt more than a century ago. Matthew Boulton, of Birmingham, had proposed to move canal boats by means of the steam-engine; and Dr. Small, his friend, was in communication with James Watt, then residing at Glasgow, on the subject. In a letter from Watt to Small, dated the 30th September, 1770, the former, after speaking of the condenser, and saying that it cannot be dispensed with, proceeds: "Have you ever considered a spiral oar for that purpose [propulsion of canal boats], or are you for two wheels?" Watt added a pen-and-ink drawing of his spiral oar, greatly resembling the form of screw afterwards patented. Nothing, however, was actually done, and the idea slept.

It was revived again in 1785, by Joseph Bramah, a wonderful projector and inventor.[5] He took out a patent, which included a rotatory steam-engine, and a mode of propelling vessels by means either of a paddle-wheel or a "screw propeller." This propeller was "similar to the fly of a smoke-jack"; but there is no account of Bramah having practically tried this method of propulsion.

Austria, also, claims the honour of the invention of the screw steamer. At Trieste and Vienna are statues erected to Joseph Ressel, on whose behalf his countrymen lay claim to the invention; and patents for some sort of a screw date back as far as 1794.

Patents were also taken out in England and America—by W. Lyttleton in 1794; by E. Shorter in 1799; by J. C. Stevens, of New Jersey, in 1804; by Henry James in 1811—but nothing practical was accomplished. Richard Trevethick, the anticipator of many things, also took out a patent in 1815, and in it he describes the screw propeller with considerable minuteness. Millington, Whytock, Perkins, Marestier, and Brown followed, with no better results.

The late Dr. Birkbeck, in a letter addressed to the 'Mechanics' Register,' in the year 1824, claimed that John Swan, of 82, Mansfield Street, Kingsland Road, London, was the practical inventor of the screw propeller. John Swan was a native of Coldingham, Berwickshire. He had removed to London, and entered the employment of Messrs. Gordon, of Deptford. Swan fitted up a boat with his propeller, and tried it on a sheet of water in the grounds of Charles Gordon, Esq., of Dulwich Hill. "The velocity and steadiness of the motion," said Dr. Birkbeck in his letter, "so far exceeded that of the same model when impelled by paddle-wheels driven by the same spring, that I could not doubt its superiority; and the stillness of the water was such as to give the vessel the appearance of being moved by some magical power."

Then comes another claimant—Mr. Robert Wilson, then of Dunbar (not far from Coldingham), but afterwards of the Bridgewater Foundry, Patricroft. In his pamphlet, published a few years ago, he states that he had long considered the subject, and in 1827 he made a small model, fitted with "revolving skulls," which he tried on a sheet of water in the presence of the Hon. Capt. Anthony Maitland, son of the Earl of Lauderdale. The experiment was successful—so successful, that when the "stern paddles" were in 1828 used at Leith in a boat twenty-five feet long, with two men to work the machinery, the boat was propelled at an average speed of about ten miles an hour; and the Society of Arts afterwards, in October, 1882, awarded Mr. Wilson their silver medal for the "description, drawing, and models of stern paddles for propelling steamboats, invented by him." The subject was, in 1833, brought by Sir John Sinclair under the consideration of the Board of Admiralty; but the report of the officials (Oliver Lang, Abethell, Lloyd, and Kingston) was to the effect that "the plan proposed (independent of practical difficulties) is objectionable, as it involves a greater loss of power than the common mode of applying the wheels to the side." And here ended the experiment, so far as Mr. Wilson's "stern paddles" were concerned.

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.