Fulton had so far built steam vessels only for commercial traffic. He now came near to revolutionizing naval warfare with them. In 1813, in the middle of the war with this country, he presented to the President his plan for a steam-propelled armoured warship for coast defence, a design of an invulnerable vessel of thirty guns, twin-hulled, with a 120-horse-power engine in one hull, a boiler in the other, and a single paddlewheel in a space between the two; double-ended, flat-bottomed, and protected by a belt of solid timber 58 inches thick. Her armament was to consist, in addition to thirty 32-pounders, of submarine guns or columbiads, carried at each end and firing 100-pound projectiles below the water-line. Named the _Demologos_, this monstrous vessel was nearly completed when the war came to an end. It was too late for use. The treaty of Ghent being signed, interest in armaments immediately evaporated. Nevertheless, in the following year a trial of the _Demologos_ was carried out, which showed that a speed of five and a half knots could be attained with her. The _Demologos_, now renamed the _Fulton_, served no useful purpose. She was laid up in Brooklyn Navy Yard, and many years elapsed before steam war vessels were built again in America. § In the meantime progress had been made on this side of the Atlantic. Stimulated by Fulton’s commercial successes, Thomas Bell of Helensburgh built in 1812 a vessel of thirty tons’ burden named the _Comet_, successfully propelled by a 3-horse-power engine which worked a paddlewheel on each beam. This “handsome vessel” was intended to ply between Glasgow and Greenock, to sail by the power of wind, air, and steam; and so it did, with fair financial success, with a square sail triced to the top of a tall smoke-stack: the first passenger steamer to ply in European waters. Shortly afterwards steam vessels were built which pushed out to the open sea. In 1815 the _Argyle_, built on the Clyde and renamed _Thames_ on being purchased by a London company, made a voyage from Greenock to London which was the subject of much comment. On making the Cornish coast after a stormy run south, boats were seen by those on board making towards her with all possible speed in the belief that she was on fire! All the rocks commanding St. Ives were covered with spectators as she entered the harbour, and the aspect of the vessel, we are told, “appeared to occasion as much surprise amongst the inhabitants, as the ships of Captain Cook must have produced on his first appearance among the islands of the South Seas.” Next day the _Thames_, her 9-foot paddlewheels driven by a 16-horse-power engine, reached Plymouth, where the crews of all the vessels in the Sound filled the rigging, and the harbour-master was “struck with astonishment.” From Plymouth she steamed to Portsmouth, making the passage in twenty-three hours. So great was the swarm of vessels that crowded round her, that the port admiral was asked to send a guard