The _Powerful_, launched at Barrow in 1895, and the _Terrible_, launched at Glasgow the same year, were the largest protected cruisers afloat at that time, and will long be remembered by the public for the excellent service their crews rendered during the Boer War, and among naval architects and marine engineers and shipbuilders by reason of the bitter controversy that arose over their installation of forty-eight Belleville water-tube boilers, they being the first cruisers in the British Navy in which these were carried. As a contrast to these two was the armoured cruiser _Drake_, begun in 1899 and completed in 1902, and at that time the largest of her class anywhere. Though called a cruiser, she was a more formidable fighting-machine than the _Barfleur_, _Renown_ or _Canopus_. With a displacement of 14,100 tons, and a length of 500 feet, and an equipment of Belleville boilers and engines developing 30,000 h.p., she and her sister ships could reach a speed of over twenty-four knots, and were faster than any other large vessels in the British Navy. She was belted on her sides with Krupp steel from one barbette to the other, and from 6 feet below the water-line to the level of the upper deck, and there was lighter armour above this. She had also two protective decks, the lower being 2 to 3 inches in thickness. Her two 9.2-inch breech-loading guns were in barbettes, and she was given sixteen 6-inch, fourteen 3-inch, and three smaller guns, which, like the last two classes, were quick-firers, and two machine guns. The increase in gun power rendered necessary an addition to the protection of the vessels, and the _Devonshire_ class of cruisers, which appeared early in the present century, were given 6 inches of armour instead of 4 inches. The ships of this class were tried for experimental purposes with four different types of water-tube boilers in combination with cylindrical boilers. These fast armoured cruisers were designed to replace the old protected cruisers, which were no longer equal to modern requirements, speed being now recognised as of very great importance. [Illustration: H.M.S. “INDOMITABLE.” _Photograph by West & Son, Southsea._] [Illustration: H.M.S. “LIVERPOOL.” _Photograph by E. Sankey, Barrow._] It is not only in the larger ships, however, that examples of such extraordinary development are to be found. Progress is shown by the smaller vessels in no less degree. The continually changing conditions of commerce have necessitated as many changes in the construction and armament of vessels whose duty it would be in time of war to protect commerce at sea, or maintain order in estuaries and rivers.