In the latter half of the eighteenth century, an engineer named Day made one successful dive in the harbor of Plymouth, England, in a boat of his own designing. He went down a second time and did not return.
It may be said in general that the necessities and opportunities of war have always been the greatest, indeed, almost the only incentive to experiments under water. The War of Independence proved remarkably stimulating to submarine invention. In 1775 David Bushnell, of Connecticut, constructed a diving boat for use against English men-of-war. A minute description of this boat is contained in a letter written by him to Thomas Jefferson in 1787. It resembled externally two upper turtle shells joined together by their edges, whence its name 'Tortoise.' It carried a crew of one man, but this man was not David
Bushnell, as it appears! During the harbor trials the boat was connected with the dock by means of a rope so that it might be recovered in case of accident. David Bushnell manipulated the safer end of this rope on the dock, while his brother, Ezra, and afterwards Sergeant Lee, did their best to learn the proper use of the mechanism within.
The following year, the first of the war, Sergeant Lee steered the 'Tortoise' beneath the hull of the British ship 'Eagle,' of 64 guns, lying off Governor's Island in New York harbor. He attempted to fix to her bottom a torpedo by means of a wood screw, but being rather unskillful still in maneuvering the 'Tortoise,' he lost the 'Eagle' altogether and was finally forced to the surface for air. Daybreak prevented further operations at that time. Two similar attempts were afterwards made on the Hudson, but they also failed and the 'Tortoise' was finally sunk by a shot.
