The _Princess Royal_ is a cruiser copy of the battleship _Conqueror_, launched the same day. The principal differences between the two vessels are that the cruiser has a pair less of the 13.5-inch guns, and also has her side armour 2 inches less in thickness, in order that she may steam thirty knots or more in place of the battleship’s twenty-one. Her beam is the same as that of the _Conqueror_, but in order to give her speed she is 700 feet over all as against the battleship’s 545 feet. In fighting power the _Conqueror_ is superior to the _Princess Royal_, the latter having only eight big guns. An idea of the enormous power required to drive these ships at the necessary speed, and especially of the increase in power as between the two vessels, is shown by the fact that turbine engines of 27,000 h.p. will give the battleship a speed of twenty-one knots, but the thirty knots of the cruiser require engines developing 70,000 h.p., or 27,000 more than the _Indefatigable_, which has done twenty-nine knots. The vessel is to be completed for sea by March, 1912. [Illustration: FRENCH CRUISER “ERNEST RENAN.” _Photograph supplied by Société Anonyme des Chantiers et Ateliers de Saint Nazaire._] [Illustration: FRENCH CRUISER “DANTON.” _Photograph by Stephen Cribb, Southsea._] It will have been seen from the dimensions quoted of the various cruisers mentioned that they are longer in proportion to their beam than the battleships, the additional length being necessary to give them greater speed. There was launched at Elswick in 1895, for the Argentine Government, the protected cruiser _Buenos Ayres_, which was very narrow for her length. Though 424 feet over all, she was only 47 feet 2 inches in beam, by 22 feet in depth. Her displacement was 4,500 tons. Her normal speed was twenty-three knots, and under forced draught twenty-four knots. Like all the warships built on the Tyne for South American States, she was heavily armed. One of the most heavily armed ships of her size early in the present century was the Japanese cruiser _Tsushima_, launched in 1902, but she has been surpassed by the later vessels of the Japanese navy in speed, coal capacity and armament, the latest, which are not yet completed, though only classed as protected cruisers of 4,035 tons, having a coal capacity of 750 to 1,000 tons, and carrying two 6-inch guns, ten 4.7-inch, and two 3-inch guns, all quick-firers, and two machine guns.