 She was the first British warship to be powered by vertical compound engines, carrying cylindrical high-pressure boilers with a working pressure of , as compared to rectangular boilers working at pressure mounted in earlier ships.Twelve boilers were set back to back on either side of a longitudinal bulkhead; each engine drove an outward rotating screw of some in diameter.A pair of auxiliary engines, each of , were fitted to turn the screws while the ship was proceeding under sail.