England at first sought to meet the new invention by improved artillery, and produced the Whitworth and Armstrong cannon, which have a range of four to five miles.  With these she practised at short distances upon targets of strong oaken plank faced with iron plates of four to five inches in diameter, but found the plates impervious to balls, and vulnerable only by steel bolts of small diameter, fired at short distances from Whitworth and Armstrong cannon,—­bolts so small that the wounds they made in the frames faced with iron usually closed or did little mischief.  A few plates of inferior iron occasionally gave way after repeated assaults, for English iron is coarsely made and poorly welded,—­a striking illustration of which may be found in a part of the hull of the ill-fated steamer Connaught, which is preserved at the ship-yard near Dorchester Point, South Boston.

England was at length convinced; she determined that she could not safely permit the Emperor of the French to rule the sea with his iron navy.  She had not forgotten St. Helena.  She realized that she had no fleet that could safely encounter one of his mail-clad warriors, and found herself obliged to copy the new invention.  She commenced last year ten iron-clad ships of the line, and has nearly or quite finished the Warrior, Black Prince, Defiance, and Resistance, while others are progressing.  But she could not tamely copy France.  Instead of confining herself to the length of the Gloire, she is constructing vessels of immense size.  The Warrior, recently launched, is four hundred and twenty-six feet in length, nearly fifty-two feet in depth, has a width of fifty-eight feet, measures six thousand one hundred and seventy-seven tons, and is moved by engines of twelve hundred horse-power.  She is to mount thirty-six cannon of the largest class, and her armor weighs nine hundred tons.

This vessel will be a formidable antagonist upon the open sea; but her great depth, with the weight of her armor, causes her to draw thirty feet, which would prohibit her entrance into most of the seaports upon our coast.  She is vulnerable, too, at each extremity.  Her iron plates, four and a half inches thick, extend but half her length, leaving more than a hundred feet at each end covered by a plate of only five-eighths of an inch in thickness; and in case these portions should be injured, she must rely upon her water-tight compartments.  An adroit foe, in a light craft of greater speed, avoiding her batteries, which are planted behind her armor, might possibly assail her unprotected ends, and, although he could not sink her, still, by shot between wind and water, he might render her more unwieldy and less manageable,—­a weight of water being thus admitted which would bring down the ship so as to endanger her lower ports and prevent the use of them in action.  He might thus also prevent her approach to shoal water.  The Warrior and her companions are, however, formidable ships, and in deep water, with ample sea-room, must be most powerful antagonists.