Captain Coles, to whom, notwithstanding the sad fate which overtook the _Captain_, this country is somewhat indebted for his consistent advocacy of the adoption of the turret on sea-going ships, urged upon the Admiralty the superiority of the turret over the broadside system. His contrivance differed from that of Ericsson in the important particular that Ericsson’s turret was supported on a pivot which rested upon bearings at the bottom of the ship, whereas Captain Coles’s turret rested upon bearings supported in a specially constructed room resting upon the beams of the deck, which, in turn, were strongly supported from below. In regard to the thickness of armour there was little to choose between the two. Captain Coles brought his design before the notice of the United Service Institution in 1860, and although it attracted a great deal of attention among naval constructors and manufacturers of naval artillery, only one nation was then of sufficient courage to order an experimental ship. That nation was Denmark, and it is to that country that the honour must be given of having the first ship in which the broadside system of gun-fire was entirely abandoned and the turret system installed instead. This vessel was the _Rolf Krake_, an iron double-turreted monitor with lowering bulwarks. She was engaged in the war against Prussia, in 1864, when she took part in a fierce duel with the Prussian batteries at Eckernsünde. The batteries fired 24-pounder rifled Krupp guns, and though the ironclad was struck about one hundred and fifty times, her armour was sufficient to withstand the shot, and she certainly inflicted a great deal more damage than she received. Numerous experiments were made in France and in this country with the object of determining the special characteristics of a vessel which should meet the rapidly altering condition of affairs caused by the increase of the power of the guns and the development of the torpedo from the stationary mine, which was so terrifying in the American War, to the torpedo which could attack a vessel at anchor, or even be directed at one moving slowly. The requirements were a moderate displacement, increased protection, and ability to carry heavier guns capable of fore and aft fire as well as over the broadside. The problem was not an easy one by any means. The cellular double bottom system was extended as a precaution against torpedoes; the number of guns and the extent of the armour were lessened, but the thickness of the armour was increased in order to protect the vital parts and the guns from the fire of the newer and more powerful ordnance, while to compensate for the increased weight in the middle third of the ship, the beam was made greater in proportion to the length. [Illustration: FOUNDERING OF THE “AFFONDATORE” IN THE HARBOUR OF ANCONA. _Reproduced by permission of the “Illustrated London News.”_] [Illustration: WRECK OF THE “CAPTAIN.” _From a Contemporary Wood Engraving._]