Another Stevens invention was that of the air-tight fire room, by Edwin A. Stevens, in 1842, whereby forced draught was rendered effective. Colonel John Stevens, in 1812, designed a steam-rotated circular fort for the defence of New York Harbour, and a year or two later, his son, Edwin Stevens, under the guidance of his father, was experimenting with a 6-pounder bronze cannon against some iron plating. The elongated shell, with which the name of Stevens is always associated, was invented by Robert L. Stevens during the war between England and America in 1813-4. The shell could be fired from ordinary cannon. [Illustration: THE “RISING STAR.” _From a Painting in the possession of the Earl of Dundonald._] “Having perfected this invention, he sold the secret to the United States after making experiments to prove their destructiveness, so decisive as to leave no doubt of the efficacy of such projectiles. One of these experiments was made at Governor’s Island in the presence of officers of the army, when a target of white oak, four feet thick and bolted through and through with numerous iron fastenings, was completely destroyed by a shell weighing 200 lb., and containing 13 lb. of best Battle powder. This solid mass of wood and iron was torn asunder; the opening made being large enough, as the certificate of the officer commanding, Col. House, stated, for a man and horse to enter. These shells are free from the danger accompanying ordinary shells, for they are hermetically sealed and suffer no deterioration from time.”[28] Some of them, indeed, were fired experimentally twenty-five years after they had been made and were found to be as effective as similar shells fired soon after they were loaded. It cannot be said that the British Admiralty was not forewarned. Even at the time of Fulton’s experiments, Lord Stanhope, who was interested in the subject, wrote to Wilberforce that “when ships of any size may be navigated so as to go without wind and even directly against both wind and waves ... it will shortly render all the navies of the world (I mean military navies) no better than lumber.” He pointed out that ships independent of wind and weather were superior to sailing ships, and that “the boasted superiority of the British navy is no more.” A new navy was necessary, and the French and other nations for the same reason would have one. His lordship proved himself a true prophet so far as the other nations were concerned, for the British Admiralty was about the last to adopt steam-driven battleships; but as to the rest of his prophecy, Trafalgar had not then been fought. When steam navigation came, it came to stay.