A 6-inch by 6-inch stoke, single cylinder inverted-vertical simple marine engine mounted on the opposite end to the fire doors of a locomotive boiler, operating at 250 revolutions per minute with steam supplied at 50 pounds per square inch, directly coupled to a propeller 2 feet 4 inches in diameter 3 feet 6 inches pitch; built by Messrs. Plenty and Sons, Newbury.