In May, 1801, Fulton built his first submarine boat, the _Nautilus_. She made her first trial on the Seine opposite the Invalides. Fulton and one sailor formed the crew and with nothing but a candle to light the interior, they remained submerged twenty minutes. On coming to the surface they found that the current had carried them some considerable distance down the river, so again sinking beneath the surface Fulton steered his vessel to the point of departure. On July 3, 1801, Fulton embarked with three companions on board his “plunging boat” in the harbour of Brest; the four men descended in the _Nautilus_ a depth of 23 feet, which seemed to be the greatest depth the boat would stand. They remained below in total darkness for one hour. At subsequent descents Fulton tried to employ candles, but found they destroyed the vitality of the air. Bulls-eyes were then inserted in the top of the boat, and these alleviated, to a certain extent, the prevailing gloom. Once Fulton with three persons is said to have stayed for six hours at a depth of 5 feet by the aid of a copper globe of 1 cubic foot capacity “containing 200 atmospheres”; on another occasion he sailed out of the harbour, then quite suddenly lowered his mast, and disappeared from view, showing how quickly he could submerge his craft. The _Nautilus_ was a cigar-shaped boat about 7 feet in diameter. The hull was of copper, but supported by iron ribs. It had one mast, a mainsail, and a jib, which moved her at the rate of two miles an hour on the surface, and were stowed in two minutes when preparing to dive. Under the water the vessel was moved by the exertions of two men, the “propelling engine” consisting of a wheel rotated by a hand-winch, at the rate of 2½ miles an hour. A third man steered from a small conning tower while Fulton governed the position of the boat by regulating the machine which kept her balanced and determined her depth below the surface. She was 21 feet 4 inches long, and was furnished with a keel under the whole length of the hull. Having proved that man could exist for some time beneath the surface in a vessel and could steer it, Fulton made experiments with a torpedo or case of explosive. On the first occasion he blew a small ship to fragments with 20 lbs. of powder. As he had shown his ability to blow up old hulks in French waters, Fulton proposed to build a large submarine vessel, but failed to attain official support, partly because those in authority considered that submarine explosions were not legal warfare. One of these writes that “this type of warfare carries with it the objection that those who undertake it and those against whom it is made, will all be lost. This cannot be called a gallant death.” [Illustration: THE “NAUTILUS” OF ROBERT FULTON. ]