It is worth noting that it was in 1836 that John Ericsson patented in England his screw propeller. A model boat forty-five feet long, which he named, for the American consul at Liverpool, the _Francis B. Ogden_, attained in 1837 a speed of ten miles an hour. The Lords of the Admiralty took a trip in this boat, and the opinion of Sir William Symonds, who spoke for the others, is worth giving as showing how thick-skulled prejudice operates to retard naval progress. He said: “Even if the propeller had the power of propelling a vessel, it would be found altogether useless in practice, because the power being applied in the stern, it would be absolutely impossible to make the vessel steer.” [Illustration: John Ericsson.] However, Capt. Robert F. Stockton made a trip on the _Ogden_, and fortunately Stockton was at once a man of wealth and of common sense. Being convinced of the value of the invention, he induced Ericsson to leave England for the United States in the year 1839, and that was, in a way, one of the most interesting events in the history of the American republic. Meantime, however, a steamer to replace the old _Demologos_, Fulton’s first war steamer, had been launched in 1837. Practically the _Fulton 2d_, as she was called, was a sloop-of-war--a ship of one deck of guns, propelled by paddle-wheels. She was broad and shallow in model, being 180 feet long by thirty-five wide and thirteen deep. She had horizontal engines lying on her upper deck. Her paddle-wheels were twenty-two feet in diameter, towering high above the deck, and her boilers were made of copper. However, she carried eight long forty-twos and a long twenty-four--a right powerful set of guns for that day, and she behaved so well that Capt. Mathew C. Perry, who was assigned to her, expressed the opinion that a time would come when sails, as a means of propelling a man-of-war, would become obsolete. However, it must be said that this remark made almost every one who heard of it, and especially the other officers of the navy, think that Perry was a “visionary.” It was in 1839 that Perry risked his reputation by an expression of opinion--about the time that Ericsson reached the United States. Backed by Stockton, Ericsson planned a man-of-war that should be driven through the water by a submerged screw at the stern. The idea of a ship being driven by machinery that was placed wholly below the water-line, and so out of danger from an enemy’s shot, was of a kind to appeal even to a backwoods congressman, and an appropriation was obtained. In 1843 the ship was launched under the name of _Princeton_, and she was in a variety of ways vastly superior to anything built before her. She was 164 feet long by thirty wide and twenty-one deep, and with 200 tons of coal and all supplies on board, she had a draft of nearly twenty feet.