In the matter of attack and defence, vessels are distinguished by the number and weight of the guns they carry, and by the distribution and thickness of their armour. Protective armour is of two kinds, that which surrounds the guns, so as to protect them from the enemy’s fire, and that which protects the motive-power of the ship, so as to prevent the engines from being rendered useless.

The maximum of guns and armour and the minimum of speed are to be found in the first-class battle-ship, which is simply a floating fortress, so constructed that she need never run away, but can stand up and fight as long as her gun turrets revolve. The general plan of construction in a battle-ship is to surround the engines, boilers, and magazines with a wall of Harveyized steel armour eighteen inches or so thick, and seven or eight feet high, which extends about four feet below the water-line and three feet above it. This armour belt is not only on the sides of the ship, but is carried across it fore and aft, immediately in front of and behind the space occupied by the engines and magazines, and the whole affair is covered with a solid steel roof three or four inches thick. Outside this central fortress, and extending from it clear to the bow and stern at each end, is a protective deck of steel, three inches thick, which is placed several feet below the water-line. Everything above this deck and outside this fortress might be shot away, and the vessel would still float and fight.

On the roof of the fortress are placed the turrets containing the big guns. The largest of these guns, 13-inch calibre, weigh about sixty tons each, and will carry a shell weighing eleven hundred pounds about twelve miles. The turrets are circular, as a rule, large enough to hold two guns, and are made of face-hardened steel from fifteen to eighteen inches thick. They revolve within a barbette or ring of steel eighteen inches thick, which protects the machinery by [pg 372]which the guns are trained. Farther back on the roof of the fortress are other and lighter turrets made of 8-inch steel and carrying 8-inch guns, and at other places are stationed rapid-fire guns of lighter calibre, protected by thinner armour than that of the main belt.

If all this secondary battery is stripped off, leaving nothing but the turrets with the big guns, and these are brought down close to the water, and the armour belt is reduced to seven or eight inches in thickness, the type of vessel known as the monitor is reached. It is simply a battle-ship on a reduced scale. Such vessels are very slow and cannot stand rough weather, on account of their low freeboard. The speed of the monitors is seldom more than twelve or fourteen miles an hour, and they are intended to act in coast defence, usually in connection with shore-batteries. The best types in the navy are the Terror and the Puritan.

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 [pg 373]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.

The next step in reducing armament and increasing speed, produced the protected cruiser, which carries no armour belt, but retains the protective deck, upon the sloping sides of which is stored the coal. The turrets disappear altogether, and there is usually only one 8-inch gun, the battery being principally made up of 4-inch rapid-fire guns and 6, 4, and 1-pounders. As this class of vessel is not able to cope with the armoured cruiser, it must be faster, for the general principle holds good that the weaker the vessel becomes in point of offensive weapons or defensive [pg 374]armour, the greater the necessity that she should be able to run away. The best types of the protected cruiser in the navy may be found in the Columbia and Minneapolis, which have a speed of about twenty-seven miles an hour.

The weakest class of all is composed of the unprotected cruisers, which have neither armour-belt nor protective deck, and carry only light batteries of rapid-fire guns. When these vessels are slow, like the Detroit, they are intended for long voyages and for duty in foreign countries, and are of little use in a sea fight. The very fast unprotected cruiser, like the American line steamers, St. Paul and St. Louis, attach little importance to their armament, and rely for protection upon stowing the coal behind the place occupied by the armour belt in other vessels. All the beautiful wood-work, which was so much admired in these vessels, was ripped out to make room for these coal-bunkers, which are sufficient to protect them from anything but the heaviest guns. On account of their extreme weakness as fighters, these cruisers are necessarily the fastest of all the large vessels, and can run away from anything. For this reason no concern was felt for the Paris by those who knew the principles which govern the safety of modern vessels.

The various types of cruisers are not expected to fight with any but vessels of their own class, which they may encounter in the discharge of similar duties, such as scouring the seas as the advance guard of the slower line of battle-ships, preying upon or escorting merchant vessels, blockading ports, and acting as convoys for troop-ships. Gunboats are simply light-draught cruisers, and are intended for use in shallow waters and rivers.

Torpedo-boats, as their name implies, depend entirely upon the torpedo as the weapon of attack, and they carry no guns except a very few light-calibre rapid-fires to keep off small boats. Their success depends on their ability [pg 375]to approach a vessel very rapidly, launch their torpedo, and retreat before they are detected and sunk. Speed is their great requisite, and a torpedo-boat like the Porter can speed thirty-two miles an hour. Naval experts consider their bark worse than their bite, because, with the modern system of lookouts and search-lights, and the accuracy and rapidity of the secondary batteries, it is impossible for a torpedo-boat to get within range without exposing itself to instant destruction, and after a torpedo-fleet has once met with a serious repulse, it is believed that it would be almost impossible to get the crews to go into action again.

The torpedo-boat destroyer, contrary to general belief, does not carry any heavy guns, but depends on its great speed and its ability to cripple a torpedo-boat with its 6-pounders while keeping out of range of the enemy’s tubes. All torpedo-boat destroyers carry torpedo tubes themselves, so that they can be used against the enemy’s battle-ships or cruisers if the occasion offers. The fastest boat in the United States navy is the destroyer Bailey, which can steam thirty-four miles an hour.

In a naval battle the success or failure of a fleet may depend on keeping open communication between the different vessels of the squadron engaged. Owing to the fact that the surface of the sea would often be obscured by the smoke of battle, the difficulty of this is apparent, and naval experts have been kept busy devising some method by which the flag-ship can communicate with the other vessels of the squadron at all times and under all conditions. So far nothing has been put in general service which meets this demand, but lately there have been experiments with the telephone, which, it is said, can be used without wires, by which signals can be projected by a vibrator on one vessel against a receiver on another. The Navy Department is [pg 376]keeping the details of this new system carefully to itself, as it desires to have the invention for the exclusive use of our own ships of battle.

The present method of communication is by the use of flags representing numerals which are displayed in the rigging; by the use of the Ardois system of lights for night work; by the Myer code of wigwag signals, and by the use of the heliograph. As it is of the utmost importance that the enemy should not read the message, the signal books on board a vessel are protected with the greatest care, and are destroyed along with the cipher code whenever it is seen that capture is inevitable. The semaphore system in use in the British navy was tried for a time aboard some of our vessels, but it never became popular, and has been abandoned.

In signalling by the navy code, the sentence to be sent is looked up in the code-book and its corresponding number is obtained. This number is never more than four figures, on account of the necessity of setting the signal with the least delay. The number having been obtained, the quartermaster in charge of the signal-chest proceeds to bend the flags representing the numerals to the signal halliards, so as to read from the top down. These flags represent the numerals from one to nine and cipher, and there is a triangular pennant termed a repeater, which is used in a combination where one or more numerals recur. The numbers refer to those found in the general signal-book, in which are printed all the words, phrases, and sentences necessary to frame an order, make an inquiry, indicate a geographical position, or signal a compass course. Answering, interrogatory, preparatory, and geographical pennants form part of this code; also telegraph, danger, despatch, and quarantine flags.

The signal, having been prepared, is hoisted and left flying until the vessel to which the message has been sent signifies that it is understood by hoisting what is called the [pg 377]answering pennant. If the number hoisted by the flag-ship is a preparatory order for a fleet movement, it is left flying until all the vessels of the fleet have answered, and then is pulled down, the act of pulling the signal down being understood as the command for the execution of the movement just communicated.

It is often necessary for a man-of-war to communicate with a merchant vessel, or with some other war-ship belonging to a foreign country. For this purpose the international code is also carried in the signal-chest. These signals are those in general use by all the merchant navies of the world for communication by day at sea. There are eighteen flags and a code pennant, corresponding to the consonants of the alphabet, omitting x and z. The code pennant is also used with these signals.

If a message is to be sent at night, the Ardois system of night signals, with which all our vessels carrying an electric plant are fitted, is employed. These signals consist essentially of five groups of double lamps, the two lamps in each group containing incandescent electric lamps, and showing white and red respectively. By the combination of these lights letters can be formed, and so, letter by letter, a word, and hence an order, can be spelled out for the guidance of the ships of the squadron. These lamps are suspended on a stay in the rigging, and are worked by a keyboard from the upper bridge.

On the smaller ships of the service, those which are not fitted with electric lighting, Very’s night signals are used. This set includes the implements for firing and recharging the signals.

The latter show green and red stars on being projected from pistols made for them. The combination in various ways is used to express the numbers from one to nine and cipher, so that the numbers, to four digits, contained in the [pg 378]signal-book, may be displayed. The Myer wigwag system is employed either by day or by night. Flags and torches are employed. The official flag is a red field with a small white square in the centre; the unofficial flag is the same with the colours reversed. The operator, having attracted the attention of the ship which is to be signalled by waving the flag or torch from right to left, transmits his message by motions right, left, and front, each motion the element of a letter of the alphabet, the letter being made up of from one to four motions.

When circumstances permit, the heliograph is sometimes used. The rays of the sun are thrown by a system of mirrors to the point with which it is desired to communicate, and then interrupted by means of a shutter, making dots and dashes as used in the Morse telegraph code. This system is used only when operations ashore are going on, as the rolling of the ship would prevent the concentration of the sun’s rays.

The present systems of flag signalling are products of experience in the past, and are the natural growth of the cruder flag system in use during the War of 1812, and in the Civil War. There have been some changes in the construction of flags, and the scope of communication has been enlarged, but otherwise our forefathers talked at sea in much the same way as we do now. Of course the Ardois light signal is something very modern. In old times they communicated at night either with coloured lights or by torches, and, as there was no alphabetical code in those days, the process was by means of flashes (representing numbers in the signal book), and it was long and tedious.