You will see in what ways a modern super-Dreadnought battleship differs from a battle cruiser if you examine the following figures
_Queen Elizabeth_ (super-Dreadnought).--Length, 620 feet; tonnage, 27,500; horse-power, 28,000; speed per hour, 25 knots;[92] armour, belt of 13½ inch thickness; armament, eight 15-inch guns and sixteen 6-inch guns.
_Lion_ (battle cruiser).--Length, 660 feet; tonnage, 26,350; horse-power, 70,000; speed per hour, 31 knots; armour, belt of 9¾ inch thickness; armament, eight 13.5-inch guns and sixteen 4-inch guns.
The _Lion_, _Tiger_, _Queen Mary_, and _Princess Royal_ are the four most powerful battle cruisers in existence.
Cruisers, of which we possessed 121 when war broke out, are the fighting scouts of the Fleet. What are called armoured cruisers, such as the unfortunate _Cressy_, _Aboukir_, and _Hogue_, are protected by belts of armour plate, varying from 6 inches to 8 inches in thickness. Protected cruisers have decks of armour plate instead of belts. The most modern cruisers, which are known as light armoured cruisers, have been described as "destroyers of destroyers." The light cruiser _Arethusa_, for example, has a belt of armour plating from 3 to 3½ inches thick. She is 410 feet long, displaces 3,600 tons, and has turbine engines that give her a speed of thirty knots. Like all the most modern warships, she consumes oil in place of coal. She mounts two 6-inch, six 4-inch, and four machine guns, with four torpedo tubes.
Next in importance to the cruisers come the destroyers, of which we possessed 227 at the beginning of the war. These vessels may be said to correspond with the armoured motor car used by the Army. They are all built for speed, and most of them can steam over thirty miles an hour. The _Swift_, the largest destroyer in our Navy, has actually done over forty-four miles an hour; the _Tartar_, however, carries off the record, with a speed of nearly forty-six miles an hour. The _Swift_ displaces 2,170 tons, and is almost as big as the smallest of the light cruisers. Destroyers of the "L" class displace 965 tons, have a speed of about thirty-three miles an hour, and carry three 4-inch guns.
Life on board a destroyer is very strenuous. Destroyers act as policemen of the seas, and they must go on their beat whatever the weather may be. If you have not seen one of these small craft riding through a gale, you can have no idea of the way in which wind and waves play pitch-and-toss with them in foul weather. Officers and men alike must wear heavy sea-boots and oilskins, for they are often up to their knees in water, and drenched with the spray that breaks freely over the decks. As a destroyer usually goes through the waves rather than over them, she is built with a raised fore part, from which in rough weather the water streams away like a little Niagara. In bad weather everything must be tightly battened down, and this means that while the deck hands are swept by cold, wind-driven sheets of water, the men in the engine rooms have to work in a very hot and stifling atmosphere. A destroyer always travels at high speed on patrol work, and she dances about on a zigzag course in order to avoid the deadly foe lurking beneath the surface. Trying though the life on a destroyer is, many men prefer it to service on a big ship. There is extra pay, which Jack calls "hard-lying money," and there is more freedom in various ways.