There occurred, however, one singular development, an aberration from the normal line of advance, the chief manifestation of which, from local and temporary conditions, was in our own country. This was the transient predominance of the monitor type and idea; the iron-clad vessel, with very few very heavy guns, mounted in one or two circular revolving turrets, protected by very heavy armor. The monitor type embodied two ideas. The first was the extreme of defensive power, owing to the smallness of the target and the thickness of its armor—the hull of the vessel rising but little above the water—the turret was substantially the only target. The second was an extreme compression of offensive power, the turret containing two of the heaviest guns of the day, consequently guns of the heaviest penetration, which could fire, not in one direction, nor in several, but in all directions as the turret revolved, and which were practically the sole armament of the ship. The defensive power of the monitor was absolute up to the extreme resisting endurance of its armor. Its offensive power must be considered relatively to the target to which its guns were to be opposed. If much in excess of that target’s resistance, there was waste of power. Actually in our Civil War monitors were opposed to fortifications, except in one or two instances when they had to contend with the imperfect structures which the Confederates could put afloat. The target, therefore, was not in excess of their gun power. Moreover, being for coast warfare, the monitor then was necessarily of small draught and small tonnage. Her battery weight, therefore, must be small, and consequently lent itself to concentration into two guns, just as the battery weight of a schooner a century since found its best disposition in one long traversing gun.