He was the son of a poor miner, and one of his earliest recollections was of the sheriff coming to take away all their household goods in payment of a debt. He was put to work in the iron mines as soon as he was able to earn a few pennies daily, and he soon developed a remarkable aptitude for mechanics. At the age of eleven, he planned a pumping engine to keep the mines free from water, and at the age of twelve, was made a member of the surveying party in charge of the construction of the Gotha ship canal, and was soon himself in charge of a section of the work, with six hundred men under him, one of whom was detailed to follow him with a stool, upon which he stood to use the surveying instruments. It reminds one of Farragut commanding a war ship, at the age of eleven. In 1826, at the age of twenty-three, he went to England to introduce a flame or gas-engine which he had invented. He remained there for eleven years, and then a fortunate chance won him for the United States. He had been experimenting with a screw or propeller for steamboats, instead of the paddle-wheels as used by Fulton, and finally, equipping a small boat with two propellers, offered the invention to the British admiralty. But the admiralty was skeptical. The United States consul in Liverpool happened to be Francis B. Ogden, a pioneer in steam navigation on the Ohio river. He was impressed with Ericsson's invention, introduced him to Robert F. Stockton, of the United States navy, and on their assurance that the invention would be taken up in the United States, closed up his affairs in England and sailed for this country. His first experiment was disastrous--though through no fault of his. A ship-of-war called the Princeton was ordered by the government and completed. She embodied, besides screw propellers, many other features which made her a nine days' wonder. A distinguished company boarded her for her trial trip, and it was decided also to test her big guns. But at the first discharge, the gun burst, killing the secretary of state, the secretary of the navy, the captain of the ship, and a number of other well known men. As a consequence, the experiment was stopped and Ericsson was twelve years in securing from the government the $15,000 he had spent in equipping the Princeton. However, he was soon to render the country a service which will never be forgotten. In 1861, he appeared before the navy department with a plan for an iron-clad consisting of a revolving turret mounted upon an armored raft. He secured an order for one such vessel, to be paid for only in the event that it proved successful. The majority of the board which gave the order doubtless laughed in their sleeves as the inventor withdrew, for what chance of success had such a vessel? There were some who even doubted whether she would float--among them her builders, who took the precaution of placing buoys under her before they launched her four months later.