The modern warship is an ever popular subject with the readers of the illustrated press. This is proved by the tenacity with which guns, ships and armor hold their place as conspicuous subjects for the pen and the brush. It is a question, however, in spite of the familiarity of the public with the technical phraseology of the warship, whether the average reader has a very accurate idea of the distinctions between the various classes of ships and between the various elements from the combination of which these ships derive their distinctive class characteristics. He is told that the "Indiana" is a battleship, the "Brooklyn" an armored cruiser, the "Columbia" a protected cruiser, and the "Puritan" a monitor. But it is probable that he has only a vague idea as to what qualities they are that mark the distinction, or why the distinctions should need to exist at all.

With a view to answering these questions in a general way, we have prepared three diagrams and a perspective drawing which show the constructive features of the several types of warship to which we have referred above. In diagrams I to III the armor is indicated by full black lines or by shading, the approximate thickness of the armor being shown by the thickness of the lines and the depth of the

shading. The fine lines represent the unarmored portions of the ordinary plating of the ships. In the end view the armor is shown by full lines and shading and the ordinary ship plating by dotted lines.

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When the naval architect sits down at his desk to design a warship of a certain size, he knows that there is one element of the vessel which is fixed and unalterable, and that is her displacement. By displacement meant the actual weight of the ship, which is, of course, exactly equal to the weight of water which she displaces. This total weight is the capital with which the architect has to work, and he uses his judgment in distributing it among the various elements which go to make up the ship. Part is allotted to the hull, part to the motive power, part to the armor protection, part to the guns, and part to the fuel, stores, furnishing and general equipment.

It is evident that the allotment of weights is a matter of compromisewhatever excess is given to one element must be taken from another; else, the ship will exceed the given displacement. Among the elements above mentioned there are some, such as weight of hull, provisions, stores, and furnishings, which for a given size of ship will not vary greatly.

Relative size of navies shown, if all ships now under construction January 1, 1904, were completed. NAVIES OF THE WORLD COMPARED.

JAPAN, 253,681 tons.

There are other elements, such as guns, armor, engines and fuel-supply, which may vary considerably in different ships, according to the type of vessel that is produced. If, for instance, the architect is designing an extremely fast ship of type No. 1, which has a speed of 23 knots, he will have to allot such a large amount of weight to the motive power that he will only be able to give the ship very slight armor protection and a comparatively light battery of guns. If he wishes to produce a fast ship that shall be more heavily armed and armored, he has to

besides protecting his water line in the region of the engines and boilers with a belt of steel of the same dimensions. The swift and lightly armed and armored ship is known as a protected cruiser; the less speedy but more heavily armed and armored ship belongs to the armored cruiser type, and the slowest ship, with its capacity for taking and giving the heaviest blows that modern guns can inflict, is known as a battleship.

In the construction of a warship the two qualities of attack and defense have to be supplied. The offer

be content with less speed, say 20 or 21 knots, as in No. 2, and the weight so saved on the motive power appears in the shape of a side belt of armor at the water line, more complete protection for the guns in the shape of barbettes and turrets and considerably heavier armament. If, again, he desires to produce a ship capable of contending with the most powerful ships in line of battle, as in No. 3, he is content with much lower speed, say 16 or 17 knots an hour, and he increases the power of his guns until they weigh over 60 tons apiece, and great protects them with redoubts and turrets of steel 1 1-2 feet thick,

sive powers are furnished by the guns, the torpedoes and the ram; the defensive powers are provided by giving the ship a complete double bottom and an abundance of watertight compartments, and by providing it with as much armor plating as it will carry to keep out the shells of the enemy. The greatest danger to which a warship is exposed is that of being sunk either by under-water attack by torpedoes or the ram, or by being penetrated at the water line by hea shell fire. The destructive force of a torpedo is so great that all that can be done is to localize its effects. For this purpose, and also to give greater structural

strength, the hull below the water line is built double-a hull within a hull. The longitudinal and transverse plate framing of the ship is built in between these shells, which are known as the inner and outer bottoms, and the space is thus divided into innumerable watertight compartments or cells. There is a possibility that a blow that would burst in the outer shell might not rupture the inner shell; but if it should, the inflow of water is confined to a limited portion of the hull by dividing the latter by transverse and longitudinal walls or bulkheads of plating. blow that burst in both outer and inner shells would only admit water to one of many compartments, and the ship would still have a large reserve of buoyancy.

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In protecting warships against shell fire it is recognized that there are

the battleship this deck is generally flat from side to side amidships for about two-thirds of the ship's length. At the sides it rests upon a wall of vertical armor from 15 to 18 inches in thickness, which extends in the wake of the magazines, engines and boilers. This side armor is usually about 7 1-2 feet in height, 3 feet of it being above and 4 1-2 feet below the water line. At each end of the side armor a transverse wall of armor extends clear across the ship. This rectangular wall with its roof of 3-in. steel thus forms a kind of inverted box, snugly sheltered below which are the before mentioned "vitals" of the ship. At each end of this inverted box two huge barbettes, with walls 15 to 17 inches thick, are built up to a few feet above the main deck, and just within and above them revolve a pair of turrets with walls of

certain parts of the ship which are of paramount importance, inasmuch as their disablement would leave it at the mercy of the enemy. These are the "vitals" of the ship, and they comprise the magazines, the boilers, the engines and the steering gear. If a shell penetrated the magazines, it would be liable to result in the blowing up of the whole ship, and if it entered the boiler, engine or steering rooms, it would probably render the ship unmanageable, in which event she would run the risk of being rammed and sunk by the enemy.

In all warships the vitals are covered by a complete protective deck of steel, which varies in thickness from 1 1-2 to 3 inches. The highest part of the deck is generally at a slightly higher level than the water line amidships, and it curves down at each end to meet the bow and the stern.

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15 to 17 inch steel. (See perspective view.) The turrets give shelter to the big guns, of which there are a pair in each, and the barbettes protect the turning gear by which the turrets are rotated. There is thus a continuous wall of 15 to 17 inch steel extending from 4 feet below the water line to the roofs of the turrets.

With this description in mind the reader will see, on looking at diagram No. III., that before heavy shells can injure the engines, boilers or guns, they must pass through from 15 to 18 inches of solid and, in the case of American battleships, face-hardened Harvey steel. The 6-inch and 8-inch guns are protected by 6 and 8 inches of steel.

Now it can readily be understood that all this amount of heavy armor and guns adds greatly to the weight of the ship, and for this reason, in