had invented a screw propeller with multiple blades on a conical base. He tested it in February 1826 on a manually-driven ship and successfully used it on a steamboat in 1829. His 48-ton ship Civetta reached 6 knots. This was the first successful Archimedes screw-propelled ship. His experiments were banned by police after a steam engine accident. Ressel, a forestry inspector, held an Austro-Hungarian patent for his propeller. The screw propeller was an improvement over paddlewheels as it wasn't affected by ship motions or draft changes. John Patch, a mariner in Yarmouth, Nova Scotia developed a two-bladed, fan-shaped propeller in 1832 and publicly demonstrated it in 1833, propelling a row boat across Yarmouth Harbour and a small coastal schooner at Saint John, New Brunswick, but his patent application in the United States was rejected until 1849 because he was not an American citizen. His efficient design drew praise in American scientific circles but by then he faced multiple competitors. Screw propellers Despite experimentation with screw propulsion before the 1830s, few of these inventions were pursued to the testing stage, and those that were proved unsatisfactory for one reason or another. In 1835, two inventors in Britain, John Ericsson and Francis Pettit Smith, began working separately on the problem. Smith was first to take out a screw propeller patent on 31 May, while Ericsson, a gifted Swedish engineer then working in Britain, filed his patent six weeks later. Smith quickly built a small model boat to test his invention, which was demonstrated first on a pond at his Hendon farm, and later at the Royal Adelaide Gallery of Practical Science in London, where it was seen by the Secretary of the Navy, Sir William Barrow. Having secured the patronage of a London banker named Wright, Smith then built a , canal boat of six tons burthen called Francis Smith, which was fitted with his wooden propeller and demonstrated on the Paddington Canal from November 1836 to September 1837. By a fortuitous accident, the wooden propeller of two turns was damaged during a voyage in February 1837, and to Smith's surprise the broken propeller, which now consisted of only a single turn, doubled the boat's previous speed, from about four miles an hour to eight. Smith would subsequently file a revised patent in keeping with this accidental discovery. In the meantime, Ericsson built a screw-propelled steamboat, Francis B. Ogden in 1837, and