SCREW PROPELLER

Evening Star, Issue 23724, 4 November 1940, Page 9

SCREW PROPELLER

INTERESTING HISTORY SUGGESTED BY FALLING StED-PGD A seed-pod fulling from a sycamore tree is said to have suggested to the brain of a Lancashire engineer the principle of tlie screw propeller. That he was intrigued by the rotary motion acquired by the pod in its descent through the air, and that it was the year 1681, is all we are told; there appears to ho no record of his having attempted to do anything about it (writes Albert George, in ‘ P.L.A.’ (Port of London Authority). Among tho earliest recorded attempts to get something done is that of .lames Watt, who, in 1770, siiggesed a “ spiral oar" for canal navigation. It was to Dr Smalls, a eollege professor who bad been experimenting in that direction, that Watt made the suggestion, and his rough sketch depicting the idea still exists; but the learned professor retorted so discouragingly that Watt subsided A [intent in respect of a method of ship propulsion by “ a wheel with inclined fans or wings, similar to tho fly of a smoko-pack or tho vertical sails of a windmill,’’ was granted to Joseph Bramah in 1785. Fixed on a spindle at the stern the wheel, “ may be wholly under water, when it would, by being turned round either way, cause the shin to be moved backward or forward.” Bramah thus seems to have had a pretty clear conception of the modern propeller, but he was before his time, and he failed to arouse public interest. Nine years later a patent for a simitar scheme was granted to a Mr Lyttelton. but he, too, faded out. Then in 1802 a t Mr John Shorter, of Doncaster, demonstrated a method of screw propulsion of becalmed sailing vessels, with man-power as the driving force.

Next comes Mr Robert L. Stevens, of Hoboken, New Jersey, who in 1801 carried out successful experiments on the other side of the Atlantic with both the single and the twin screw ideas. Later in the records are such prominent engineering names, as Trevithick, Millington. Lowe, Whvtock, Perkins, and Samuel Brown, all of whom experimented to some extent with the screw method of propulsion. The type of screw favoured by the last-mentioned consisted of two blades fixed to a shaft either in the bow of the ship or at the stern. It was. demonstrated on the Thames in 1823, in a vessel 60ft long, when it developed a speed of about seven miles an hour. The power was supplied bv a gas-vacuum engine, which also wag the invention of Mr Brown. Another screw aspirant was a London merchant named Charles Cmnmerow, who took out a patent in 1828. But steamship companies continued to turn a deaf ear, and went on fitting new ships with paddle-wheels in the orthodox manner, while the Admiralty maintained traditional indifference. Next we hear a story from France of the type so frequently told in connection with inventions. Frederic Sauvage, a military engineer of Boulogne, on leaving the French army in or about the year 1826, devoted himself to marine engineering. For 10 years ho experimented with an idea for a screw propeller, and at last, satisfied with its practicability, he patented it. His research work had so impoverished him, however, that he had got into debt; and for a paltry sum he was imprisoned. During his period in jail, during which his provisional patent expired, two rogues stole his idea and sold it to a shipbuilding firm. The first ship to be fitted with Sauvage’s screw was the Napoleon, a French Government vessel; and in 1839, released from prison, poor Sauvago had thd mortification of seeing that ship at Le Havre functioning by means of the screw constructed from his plans. Ho sued the shipbuilders, but was unsuccessful; and he died at Le Havre shortly afterwards, a broken man.

lii the meantime an English farmer had been constructing ship models and trying various methods of propelling them, using a clock spring for power. Ho was Mr Francis Pettit Smith, and

a public demonstration was arranged at the Welsh Harp at Hendon in 1834 with a model having a wooden screw driven by clockwork. In May, 1836, ho took out a patent. His next move was to form a company; but no engineer would risk professional ridicule by constructing the necessary machinery. Kventually, however, Sir John and Mr George llennie not only undertook to construct the machinery, but subscribed a thousand pounds each to the company. Smith laid no claim to the invention of a screw propeller, but only in its design and in the position in which he placed it—namely, in the “ deadwood ” between the 'stern post and the keel of tho ship. In one respect the design was achieved partly by accident, for during one of his trials damage sustained by contact with wreckage rendered the screw more effective. A small steamer was constructed ami fitted with a screw in accordance with the Smith formula. Her first trial was mada in November. 1833. on the Grand .Innetioa Canal at Paddington. Later she was p it on the Thames and accomplished a run from ’Black-wall to Margate in eight and a-half hours. Tin’s performance was deemed so satisfactory 1) v the mow constituted Smith Screw Propeller Company that orders wore given for the building of a screw-driven sea-going craft of 230 tons. 125 ft long, and with a 22ft beam. In rlne course this vessel. IniiJt on the Thames and christened Archimedes. was tried in company with two Dover-Oalais mail packets with most satisfactory results.

At this time (18391 the building at Bristol of the steamer Great Britain for the Great Western Steamship Company bad just begun, and the directors wore invited by the Smith Propeller Company to take a trip in the Archimedes. and they wore so impressed by tho ship’s performance, especially in some rough weather which they happened to encounter, that orders were given to suspend work on tho machinery of the Great Britain pending a report from the company’s engineer, tho eminent Mr Isambard Kingdom Brunei. The report was drawn up, and Brunei, in face of a certain amount of opposition, induced the directors to change their plans and substitute a Smith propeller for the intended paddle wheels. Thus fell to the Great Britain the honour of being the first screw-fitted Atlantic steamer. In addition to Francis P. Smith and tho unfortunate Frenchman Sauvage, there was yet a third man who was working on the same idea during the same period. He was Captain Ericsson, of the Swedish navy, who patented a screw propeller in July, 1836, only two months later than Smith. Ericsson demonstrated his device on tho Thames with a boat called the Francis B. Ogden. She was fitted with two propellers, each sft Sin in diameter, and developed a speed of 10 miles an hour. She made several trial excursions, and was on one occasion used as a tug; but, although she did all her promoter claimed for her, and although the tests were witnessed by officials of the British Admiralty, Ericsson received no support whatever in this country. But among those - who witnessed tho trials of tho Francis B Ogden was Commodore Stockton, of tho United States navy, and he was sufficiently impressed to order from Captain Ericsson two small boats fitted with his type of propeller. These were built and taken to America in 1839.

The British Admiralty were still sceptical, hut eventually agreed to the construction of a screw-driven ship, the Rattler, of 900 tons and 200 horsepower, and on August 24, 1844, a trial was arranged against H.M.S. Prometheus, a paddle steamer of similar tonnage and power. As was expected, the Rattler (the new ship) beat the Prometheus, her screw driving her at 9.89 knots against tho paddler’s 8.89. The Admiralty next arranged for the Rattler to try her strength against the Alecto. The two ships were tied together stern to stern by hawsers. For some time they tugged against each other with force so equal that neither vessel moved the other. Then tho Rattler began to get tho better of the contest, and eventually dragged her struggling adversary away at a speed of nearly three miles an hour.

Thus tho screw propeller came into use in throe different parts of tho world practically simultaneously—the Smith propeller in this country, the Sauvage on the Continent, and the Ericsson in tho United States. Of the three promoters, tho first-named received most of the honour. Ho was knighted in 1871, his portrait was placed in tho National Maritime Museum at Greenwich, and a model of his ship Archimedes is in the Science Museum at South Kensington. Of Sauvage we read that his actual first screw is (or was) in the Paris Museum of Technology, and of Ericsson there is honourable mention in the annals of the United States navy and of the navy of his native Sweden.