Twin-screw launch engines and boiler built by Messrs. Alex Wilson and Co., of Vauxhall Iron Works, London, for a launch 65 ft. long by 12 ft. beam, and a light-load draught of 2 ft. 6 in. Each engine had two cylinders 7.5 in. in diameter and 8 in. stroke, operating on steam supplied by a locomotive boiler, driving propellers 3 ft. 3 in. in diameter 4 ft. 6 in. pitch, making 300 revolutions per minute, and