The speed of a battle-ship is about eighteen miles an hour. The best specimen in the navy is the _Indiana_, declared by its admirers to be the most powerful battle-ship afloat. Second-class battle-ships, like the _Texas_, are smaller vessels, usually about seven thousand tons, and they have a much lighter armour belt, about twelve inches, and do not carry so heavy an armament as ships of the first class. The _Maine_ was a second-class battle-ship. Her largest guns were of 10-inch calibre; her armour was twelve inches thick, and her turrets were eight inches thick only. The first step in reducing the armament from that of the battle-ship proper, at the same time increasing the speed, produces the armoured cruiser. This type of vessel may carry no guns of more than 8-inch calibre, and the armour belt is reduced to three or four inches in thickness. Instead of the roof over the armour belt, the protective deck is carried all over the ship, but it is not flat, nor is it of equal thickness, as in a battle-ship. On the top and in the middle it is three inches thick, but the sides are six inches and they slope abruptly to below the water-line. Between these sloping sides and the thin armour belt coal is stored, so that a shell would have to penetrate the outer belt, six or eight feet of coal, and a sloping belt of steel six inches thick, the total resistance of which is calculated to be equal to a solid horizontal armour plate fifteen inches thick. A cruiser is not supposed to fight with a battle-ship, because it could not accomplish anything with its 8-inch guns against the 18-inch armour of its heavier rival, while one well-directed shot from the 12-inch guns of a battle-ship or monitor would probably sink any armoured cruiser afloat. For this reason the cruiser must be faster than the battle-ship, so that she can run away, and the weight that is saved in the armour belt and big guns is therefore put into the engine-room. The average speed of an armoured cruiser is about twenty-four miles an hour, and the best types of this class in the navy are probably the _Brooklyn_ and _New York_. Some vessels, like the Spaniard _Vizcaya_, are about half way between a battle-ship and a cruiser, having the heavy guns of the former and the speed of the latter. The _Vizcaya_, although a cruiser, carried 11-inch guns with a 12-inch armour belt, and had a speed of twenty-three miles an hour.