Two giant propeller engines, with a combined weight of 340 tons, were installed amidships. They were built to a modified patent of Brunel's father Marc. The engines, which rose from the keel through the three lower decks to a height just below the main deck, were of the direct-acting type, with twin bore, stroke cylinders inclined upward at a 60° angle, capable of developing a total of at 18 rpm. Steam power was provided by three long by high by wide, "square" saltwater boilers, forward of the engines, with eight furnaces each – four at each end.