Under each of these sheds he will find an iron steamship, two hundred and seventy-five feet in length by twenty-three in depth, exquisitely proportioned; he will be struck by the fine entrance and run.  The extreme sharpness of the stem and stern, combined with great capacity, seems to answer every requirement; and he will be surprised to learn that the draught of these steamers is but sixteen feet when deeply laden, and that their engines of thirteen hundred horse-power are expected to give them a speed of fifteen knots per hour.  When they reach their destined element and have received their lading, the height from the water-line to the deck will be but seven feet; hence it is apparent that a belt of iron plates carried around them of eight feet four inches in height would protect them from the deck to a point sixteen inches below the water-line, or from the bottom of the deck-beams to a point two feet below the water-line.

The iron plates which form the sides of these ships range in thickness from one inch below the water-line to three-fourths of an inch above it.  And if we allow for the superior strength and toughness of American iron, an additional plate of three inches in thickness would suffice to give them more strength than that of either the French or English mail-clad steamers.

By careful computation we have ascertained that each vessel might be encircled by such plates, weighing but one hundred and twenty pounds per superficial foot, and have her bulwarks plated also, without adding more than three hundred tons to her weight,—­actually less than one-third of the cargo she was designed to carry.  With an extra planking within, and an armament of twenty-four rifled fifty-pounders or Whitworth cannon, and select crews, such vessels need fear no antagonists upon the deep.  Low in the hull, they would offer but little surface to the fire of the enemy, and their sides would be impervious to shot and shell.  Beneath the decks they could carry in safety a whole regiment of troops.  Selecting their position by superior speed, they could destroy a fleet of wooden steamers or ships-of-the-line.  Entering any of our large seaports, they could pass the fortress at the entrance uninjured, and lay cities under contribution, or destroy their ports, without being, like Achilles, or the English “Warrior,” vulnerable in the heel.

When such steamers come into general use, we shall hear no more of the wooden walls of Greece or England, or of those modern platforms which had not a stick of sound oak timber in them,—­nothing, indeed, but pitch-pine and cypress.  Oak, pine, and cypress would fall into the same category, when contrasted with the imperishable iron.  Some new agency of steel must be invented to cope with the adamantine iron.  And it becomes our Government, both for the armament of our ships and for defence against iron steamers, to adopt at the earliest moment every improvement in rifled cannon.