Robert Fulton - Nautilus Submarine 1801Robert Fulton's cigar-shaped Nautilus submarine was driven by a hand-cranked propeller when submerged, and had a kite-like sail for surface power. The Nautilus submarine was the first submersible to have separate propulsion systems for surfaced and submerged operations. It also carried flasks of compressed air that permitted the two-man crew to remain submerged for five hours.
William Bauer - 1850William Bauer, a German, built a submarine in Kiel in 1850, but met with little success. Bauer's first boat sank in 55 feet of water. As his craft was sinking, he opened the flood valves to equalize the pressure inside the submarine so the escape hatch could be opened. Bauer had to convince two terrified seamen that this was the only means of escape. When the water was at chin level, the men were shot to the surface with a bubble of air that blew the hatch open. Bauer's simple technique was rediscovered years later and employed in modern submarines' escape compartments that operate on the same principle.