This syndicate built the steam-ship _Archimedes_, the first seagoing vessel driven by a screw propeller. She was of 232 tons, and had engines of 80 horse-power. The cylinders were 37 inches in diameter and of 3 feet stroke, and the screw, being geared in the proportion of a fraction over five to one, made 140 revolutions per minute to about 27 revolutions of the engine shaft. The screw was formed of plates of iron fastened to arms of wrought iron, keyed upon a wrought-iron shaft. The boiler was suited to the shape of the vessel. The engines, chimney, boiler, coal-boxes, driving machinery, and propeller weighed altogether rather more than 64 tons. The propeller was fitted in such a way that it could be brought on deck for repair or when not required for use. The ship was 125 feet over all and 22¹⁄₂ feet beam. Various types of propeller blades were tried with her, and she was also sent on a voyage round the ports of Great Britain to demonstrate the effectiveness of this method of propulsion. On this trip she called at Bristol, where the _Great Britain_ was under construction, and was thus the cause of the screw propeller being adopted for that ship. One of the tests to which the _Archimedes_ was subjected was a voyage between Dover and Calais in the company of two of the Post Office packets, which she beat handsomely. She went from London to Portsmouth in 1839, and continuing her voyage round the ports of the British Islands, to provide ocular proof to all interested, put in at Plymouth, where she was boarded by Admiral Sir Grayham Moore and the Commander-in-Chief, who were then convinced of the usefulness of the screw. The next year the _Novelty_ was built for the owners of the _Archimedes_ by Mr. Wimshurst at Blackwall, to demonstrate still further the seagoing merits of a screw-propelled vessel. Her two-bladed screw was placed as near the sternpost as possible, and one of its features was that it had only a quarter of a turn to the blade. Her boilers worked at a steam pressure of sixty pounds above that of the atmosphere, the highest then attempted, and up to then regarded as impossible for a steamer. She took a general cargo to Constantinople, to which port she was the first screw cargo boat to go; but as on her return objections were raised that the pressure was too high, other engines were substituted working at only a quarter of the pressure. She was one of the few vessels in which the mast was used as a funnel, her mizzen-mast being made hollow and of iron for the purpose: she is also said to have been the first vessel to be fitted with an iron mast.