Forts are competent to resist and repel vessels.

Both these principles have been well settled by military experience, and have received full illustration in the recent attack on Fort Pulaski. While that fort fell before a powerful land attack, an attack exacting much time and labor of preparation, and the employment of guns of a caliber never before use for breaching, it is also true that the heavy squadron cruising in those waters for months past, that has lately given such brilliant proofs of its power and energy, and of the ability by which it is directed, some of the vessels of which are armed with the largest guns that have ever been used a float, made no attempt to pass the fort, and did not engage its fires at all, but waited passive for its reduction by a different and the only legitimate process.

Local circumstances may, though rarely, permit a formidable preparation of a more purely naval character; that is to say, a large array of mortar-boats to act by bombardment upon sea-coast fortifications. Against this sort of attack the garrison must be sheltered and the guns covered by bombproof. When these are properly prepared, with dimensions proportioned to the projectiles to which they are to be exposed, the guns can be preserved uninjured, and the garrisons in condition to serve them, really for the time when the vessels shall approach. The whole scope of fire of the fort must be freed from trees and whatever will hide or screen the attacking force, and the vessels, held in open sight, must be plied not only with shot, but also with large shells from the mortars of the fort.

These general views being premised, it may now be considered how far the changes now making in ordnance and projectiles, and in naval warfare, require corresponding changes to be made in our forts and other means of land defense.

Artillery has been greatly increased in size, and its enlarged projectiles have longer ranges, increased accuracy, and greater penetration. It has become much more formidable, but it has no new quality added to it. Its old qualities are greatly improved. Forts must be made capable of resisting ships possessing these formidable guns. Ships, however, will henceforth be exposed to like formidable ordnance in the forts. It does not appear that the use of large guns on both sides works to the exclusive advantage of ships. Ships, however, can be heavily clad with iron; but to this defensive provision there is a limit soon to be reached, if it be not already attained. The armorclad vessel must be able to bear the shock of the waves, to receive all her supplies, to steer, to navigate, and to enter shallow water. If a vessel can be constructed capable of these things, while at the same time she is absolutely shotproof, our confidence in fortifications might be gravely shaken. But already it is seen, as the result of experiments both here and abroad, that iron plates six and eight inches thick, nearly if not quite the limit of thickness that a vessel can carry, are broken-ruined-by our ordinary large guns-guns no larger than are now common in service use. At the same time it is perfectly plain that there is no limit of this kind whatever to the thickness of the iron plates with which our forts may be covered whenever, if ever, it shall become necessary to resort to armor for them. But, further, guns are now being prepared capable of throwing a projectile three or four or more times as large as those that are now in use. There is reason to think that there is no limit to the seize of guns that may be produced and used with facility upon stable shore batteries-cannon,