United States. Another new and valuable principle was introduced in the Princeton—that of applying the power directly to the shaft turning the screw. Ericsson's propellers with direct-acting engines below the water line were also applied in the French frigate Pomona in 1843, and in the British frigate Amphion in 1844. The Princeton was fitted with a twelve-inch wrought-iron gun, forged after Ericsson's designs, and strengthened with bands, which had been tested; and with a heavier gun ordered by Captain Stockton, called the Peacemaker. This gun, when fired—Ericsson's friends claim, against his advice—during a visit of President Tyler and members of his Cabinet to the Princeton, February 28, 1844, burst, killing the Secretaries of State and the Navy, and Colonel Gardiner, of New York.
From the year 1826 Ericsson had entertained the idea of contriving an “impregnable and partially submerged instrument for destroying ships of war,” and had a plan matured for it in 1835; and the idea of protecting war engines for naval purposes was as old with him, he wrote, as his recollection. He had become satisfied also that armor plates that a vessel could carry could not be forged which a gun could not be constructed to penetrate if fired directly at them. From these ideas was developed the plan of the submerged vessel carrying a turret, which was embodied in the Monitor. In August, 1861, he proposed to President Lincoln to build a vessel for the destruction of the Confederate war-craft, declaring that his purpose was not private profit but only to serve his country. No settled purpose or idea of what was to be done seems to have existed in Washington; but Ericsson, after presenting his plans, was directed to construct the Monitor according to them, within a hundred days. The result of the first experiment with this vessel constitutes one of the sensational incidents of history. The Monitor's guns were not allowed to be charged in that action as heavily as Ericsson desired—they would have borne, in fact, a charge three times as great as was given them—consequently the Merrimac was not destroyed, as it probably might have been. Nine other monitors were built for the Government by Ericsson and his business associates, of which the Dictator was completed, as he reported to the Navy Department, with a displacement of a fraction of an inch less than he had calculated.
In 1869 Captain Ericsson contracted to furnish the Spanish Government with thirty gunboats after his own designs, for use against Cuban insurgent blockade-runners. They were all afloat within four months, two months before the time they were to be called for by the contract, and half of them had their engines and boilers on board. Several novel features were introduced upon them; they proved admirably adapted to their purpose; and in