Armour-plated batteries found their chief representatives in the batteries of the time of the Crimean War, of which the _Glatton_ and _Terror_ may be regarded as types, and the double-turret principle was developed in such vessels as the _Cerberus_. The _Terror_ was built by Palmer’s for the destruction of the Cronstadt forts. She had three masts carrying square sails on the fore-mast, and excessively sloping sides and bluff ends, and would form a remarkable contrast to the graceful lines of the modern battleship. The _Terror_ was built, armour-plated, and launched in about three months, thanks to Sir Charles Palmer’s invention of rolling instead of forging the armour plates. The battle of Tsushima afforded naval architects some valuable lessons, and the _Dreadnought_ and the _Lord Nelson_ may be regarded as the first results. The Japanese-built _Satsuma_ is virtually on the same lines, there being little to choose between the _Satsuma_ and the _Lord Nelson_. The _Dreadnought’s_ turbine machinery drives four shafts, and immediately aft of the inner shafts are twin rudders to give the ship greater steering facilities. The Admiralty adopted turbines, according to an official statement, because “of the saving in weight and reduction in number of working parts, and reduced liability to breakdown; its smooth working, ease of manipulation, saving of coal consumption at high powers, and hence boiler-room space and saving of engine-room complement; and also because of the increased protection which is provided for with this system, due to the engines being lower in the ship: advantages which more than counterbalance the disadvantages. There was no difficulty in arriving at a decision to adopt turbine propulsion from the point of view of seagoing speed only. The point that chiefly occupied the committee was the question of providing sufficient stopping and turning power for purposes of easy and quick manœuvring. Trials were carried out between the sister vessels _Eden_ and _Waveney_, and the _Amethyst_ and _Sapphire_, one of each class fitted with reciprocating and the other with turbine engines.... The necessary stopping and astern power will be provided by astern turbines on each of the four shafts. “These astern turbines will be arranged in series, one high- and one low-pressure astern turbine on each side of the ship, and in this way the steam will be more economically used when going astern, and a proportionally greater astern power obtained than in the _Eden_ and _Amethyst_.” Messrs. John I. Thorneycroft and Co.’s first torpedo-boat for the British Navy was the _Lightning_, of 18 knots, but the firm’s _Tartar_, launched in 1907, broke all records by travelling at 35·67 knots. The latest destroyers have a speed of 33 knots, though the coastal destroyers have a speed of only 26 knots. Another remarkable feature in the Navy of late years has been the number of vessels to be fitted with oil-burning apparatus instead of coal.