A committee of naval and military officers was appointed which made numerous tests, and as a result Congress entered into a contract with Stevens for the construction of “a war steamer, shot and shell proof, to be built principally of iron,” and making an appropriation for the purpose. Up to this time there had been but little change in the power of guns since the time of Nelson, but Commodore R. F. Stockton’s successful construction in England of a wrought-iron gun throwing a round shot able to pierce a target 4½ inches thick, induced Robert Stevens, who was associated with Edwin A. Stevens, to alter the plans and increase the thickness of the armour so as to fulfil his contract to build a ship that should be “shot and shell proof.” The production of still more powerful guns, both in America and Europe, caused more alterations and delay. It is of interest to note the dimensions of this vessel in order to see to what an extent Stevens anticipated the designs of some later engineers. When Robert Stevens died, in 1856, the ship was then 410 feet long, 45 feet inside the armour shell, with two feet of freeboard, and with a square, immovable turret enclosing depressible guns. She had her engines and boilers, and it would not have taken long to complete her; but for some reason, which need not be gone into here, except that the vessel was too far in advance of the officials at Washington, who were wedded to wood and sail, she was never launched, and was ultimately sold in 1881 for old material. Besides being armoured and turreted, she had a powerful ram of the “axe-head” pattern. [Illustration: THE STEVENS BATTERY.] A writer in the _Cosmopolitan Magazine_ for May, 1898, says:--“That the Stevens battery would have been irresistible as a ram and invulnerable as a fort is easy to be seen; but the Stevenses were condemned in this case by official obstruction to undeserved failure.... During these years, though constantly undergoing alteration and reconstruction, she was at all times in a condition which would have admitted of her rapid completion had an emergency arisen, on the plans which were for the moment being carried out, and these plans were always so far in advance of general naval construction that if so finished she would have been a match for a fleet of the best vessels of the world at the same time. Thus, while the naval armament of the world was light, her original armour of 4½ inches would have rendered her invulnerable to the shot of an enemy, while her shell guns would have meant certain destruction to any vessel not provided, like herself, with an armour capable of keeping out such shells. As the size and penetrating power of cannon shot were increased, so was the provision for heavier armour made in the Stevens battery, and her own guns were at the same time enlarged in the successive designs.” This refers to the period immediately prior to the American Civil War.