The ability to contend with armored vessels of the first class must be reserved for another type of ships, which are styled “coast-defence vessels,” and without which our new navy will not be thoroughly equipped for contributing its full share to defence at home. In considering armored vessels, what was said before as to the character of compromise that obtains in vessels-of-war must be borne in mind. All desirable features cannot be concentrated in any one ship; the special duty for which the vessel is to be used controls the selection. The sea-going armored cruiser is expected to keep the sea for a lengthened period: she must have large coal endurance. She may be called on to sustain more than one engagement: her supply of ammunition must be large. Her speed must equal that of the fastest sea-going vessels of similar type to enable her to pursue an equal or to avoid a superior force: hence much space and displacement must be assigned to engines and boilers. Thus the amount of her armor and the weight of her battery are affected by these other demands, which are the more imperative. In the case of coast-defence vessels the conditions are changed, enabling in them the full development of both offensive and defensive properties. These vessels are assigned to duty on the coast: they must be as fit to keep the sea as are the armored cruisers, and they must be able to fight their guns in all weathers that the armored cruiser can fight; but as they do not require the coal endurance nor the speed of the ship that is to keep the sea for lengthened periods, the weight saved in coal and machinery can be utilized in battery and armor. Such vessels constitute the main line of naval defence, as they can be made almost absolutely invulnerable and irresistible. Under an act of a late Congress a board on “fortifications and other defences” was occupied in considering the defences of the coast, and there were recommended by this Board two classes of “floating batteries” (so called), coast-defence vessels, and one class of low freeboard vessels for harbor defence. An examination of the designs of these vessels shows that they are replete with merit, and present some novel and valuable features. A justifiable limitation is put on the coal endurance and speed, though fair speed is secured; and altogether the plans prove there can be designed vessels of comparatively small dimensions, light draught, great handiness and manœuvring power, which can carry the heaviest guns, and be capable of contending on equal terms with the heaviest European battle-ships. The cut below represents the smaller of the type of coast-defence vessels. [Illustration: LIGHT DRAUGHT COAST-DEFENCE VESSEL, WITH DECK PLAN.] The largest class will be armed with two 107-ton guns in a turret, and two 26-ton guns in a barbette. The thickness of armor will vary from 16 to 18 inches.