_Crash!_ The image in the periscope has disappeared, and the submarine rocks slightly. The periscope has been sighted by a keen eye on the _Birmingham_, and a superb shot has carried it away. The submarine is now as blind as the giant after Ulysses had bored into his one eye. The biter has been bitten. It cannot remain under water, for a touch of the cruiser's steel bow will be the stroke of doom. If it comes up, a storm of shell will rage about it. The commander has a choice of perils. Desperately he decides to come up and endeavour to fire another torpedo. The horizontal rudders are set in motion; compressed air is admitted to the ballast chambers, and some of the water is blown out. The conning-tower rises above the level of the water; but, before she can use her sting, all is over. The cruiser's quick-firing guns have been waiting, and the moment the deck appears a four-inch shell is discharged at it. The armour at the base of the conning-tower is cleft through as though it were a biscuit-box. Water rushes in, and a minute later the ill-fated craft, a marvel of ingenuity, lies on the bottom, twenty fathoms deep. There it will rust away long after the war in which it played such a brief part has passed into history. * * * * * Such is the story of how H.M.S. _Birmingham_ sank the German submarine U 9. Some accounts tell us that the periscope was not shot away, but that when the torpedo from the submarine missed its mark, the cruiser made a rapid turn and drove straight at her, crumpling her to pieces by the terrible force of its weight and speed. This is the method which our cruisers usually adopt when attacked by submarines. They steam rapidly in a zigzag course, so as to disconcert those who are aiming the torpedo, and, at the first sign of the submarine's presence, charge down upon her and sink her. [Illustration: A cruiser ramming a submarine.] [Footnote 174: See p. 181.] [Footnote 175: Destroyers are fast warships, smaller than cruisers, and are meant to act against torpedo boats of the enemy. They also engage in scouting and patrol work. Some of them have a speed of more than 40 knots, and carry 105 men. All are armed with quick-firing guns and torpedoes.] [Footnote 176: War vessels built mainly for speed. They were originally used for scouting, but nowadays they are little inferior in strength and gun power to battleships. A battle cruiser is really a battleship with high speed. The _Lion_, for example, has a tonnage of 26,350 tons, and steams over 30 miles an hour. She carries eight 13.5-inch guns, and sixteen 4-inch guns. The _Lion_, the _Tiger_, the _Queen Mary_, and the _Princess Royal_ are the most powerful battle cruisers in existence.] [Footnote 177: _Am-fī´on._] CHAPTER XVIII. INFANTRY AND ITS WORK.