CLASS II.  This differs from the first mentioned in having protection all around at the water-line.  The New Ironsides, (American,) of 3,250 tons, 240 feet length, 58-1/2 feet beam, 28-1/2 feet depth, and 15 feet draught, and built of wood, has 4-1/2-inch solid armor with 2 feet backing, extending from the upper deck down to 4 feet below water, with vertical bulkheads like the Warrior, making a casemate 170 feet long, in which there are sixteen 11-inch smooth-bores and two 200-pounder Parrott rifles.  A streak of armor, 4 feet below water and 3 feet above, runs from this forward and aft entirely around the vessel.  Her speed is 8 knots.  The Stevens Battery, (American,) 6,000 tons, constructed of iron and nearly completed, is 420 feet long, 53 feet wide, and 28 feet deep from the top of the casemate, and is iron-clad from end to end along the water-line.  As proposed to the last Congress, the central casemate was to be about 120 feet long on the top, its sides being inclined 27-1/2 degrees from the horizon, and composed of 6-3/4 inches of iron, 14 inches of locust backing, and a half-inch iron lining.  Upon the top of it, and to be loaded and manoeuvred from within it, were to be five 15-inch smooth-bores and two 10-inch rifled guns clad with armor.  The actual horse-power of this ship being above 8,000, her speed would be much higher than that of any other war-vessel.  Congress, declining to make an appropriation to complete this vessel, made it over to Mr. Stevens, who had already borne a considerable portion of its cost, and who intends to finish it at his own expense, and is now experimenting to still further perfect his designs.  The Achilles (English) now building of iron, about the size of the Warrior, and of 6,039 tons, with a casemate 200 feet long holding 26 guns, belongs to this class.  The Enterprise, 180 feet length, 990 tons, 4 casemate-guns, and the Favorite, 220 feet length, 2,168 tons, 8 casemate-guns, are building in England on the same plan.  The Solferino and Magenta, (French,) built of wood, and a little longer than the Royal Oak, (see Class III.,) are iron-clad all round up to the main deck, and have two 13-gun casemates above it.

CLASS III.  The Minotaur, Agincourt, and Northumberland, 6,621 tons, and 390 feet length, resembling, but somewhat larger than the Warrior, in all their proportions, and now on the stocks in England; are built of iron, and are to have 5-1/2-inch armor and 9-inch backing extending through their whole length from the upper deck to 5 feet below water, forming a casemate from stem to stern, to hold 40 broadside-guns.  Five vessels of the Royal-Oak class, 4,055 tons, building in England, 277 feet long and 58-1/2 feet wide, are of wood, being partially constructed frigates adapted to the new service, and are iron-clad throughout their length and height to 5 feet below water.  They are to carry thirty-two 68-pounders.  The Hector and Valiant, 4,063 tons, and 275 feet long, are English iron vessels not yet finished.  They are completely