The first known treatise on submarines was written in 1578. Published by William Bourne in his Inventions or Devices, the document describes a ship with two hulls, the outer made of wood and the inner made of leather. While no record exists concerning its manufacture, the ship, according to Bourne, could be submerged or raised by taking in or expelling water from between the double hulls. The first known submarine to be built was that of Dutch inventor Cornelius Drebbel, which consisted of greased leather over a wooden framework. It was propelled either on or beneath the surface by eight oars sealed through the sides with leather flaps. During a demonstration for James I in 1620, this vessel was successfully piloted just under the surface of the Thames River. It was unable, however, to make deep descents. During the American Revolution David Bushnell built a one-man submarine called the Turtle...