n8 THE POPULAR SCIENCE MONTHLY. 



United States. Another new and valuable principle was intro- 

 duced in the Princeton that of applying the power directly to 

 the shaft turning the screw. Ericsson's propellers with direct-act- 

 ing 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 Cap- 

 tain 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 con- 

 triving 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 em- 

 bodied 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 Erics- 

 son, 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 sen- 

 sational 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 Depart- 

 ment, 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 



