Submarine navigation was a century and a half old before it claimed its first victim. J. Day, an English mechanic, rebuilt a small boat so that he was able to submerge it in thirty feet of water, with himself on board, and remain there for twenty-four hours with no ill effect. At the end of this time, Day rose to the surface, absolutely certain of his ability to repeat the experiment at any depth. But how could he turn this to practical account? [Illustration: Symons’s Submarine.] It was an age of betting, when gentlemen could always be found to risk money on any wager, however fantastic. Day found a financial backer in a Mr. Blake, who advanced him the money to buy a fifty-ton sloop and fit it with a strong water-tight compartment amidships. Ten tons of ballast were placed in the hold and twenty more hung outside the hull by four iron rods passing through the passenger’s compartment. When the rest of the boat was filled with water, it would sink to the bottom, to rise again when the man inside released the twenty tons of outer ballast. Shut in the water-tight compartment of this boat, Day sank to the bottom of Plymouth Harbor, at 2 P.M., Tuesday, June 28, 1774, to decide a bet that he could remain twelve hours at a depth of twenty-two fathoms (132 feet). When, at the expiration of this time, the submarine failed to reappear, Mr. Blake called on the captain of a near-by frigate for help. Bluejackets from the warship and workmen from the dockyard were set to work immediately to grapple for the sunken craft and raise her to the surface, but to no avail. The great pressure of water at that depth--150 feet is the limit of safety for many modern submarines--must have crushed in the walls of the water-tight compartment without giving Day time enough to release the outer ballast and rise to safety. CHAPTER II DAVID BUSHNELL’S “TURTLE” In the first week of September, 1776, the American army defending New York still held Manhattan Island, but nothing more. Hastily improvised, badly equipped, and worse disciplined, it had been easily defeated by a superior invading force of British regulars and German mercenaries in the battle of Long Island. Brooklyn had fallen; from Montauk Point to the East River, all was the enemy’s country. Staten Island, too, was an armed and hostile land. After the fall of the forts on both sides of the Narrows, the British fleet had entered the Upper Bay, and even landed marines and infantry on Governor’s Island. Grimly guarding the crowded transports, the ship-of-the-line _Asia_ and the frigate _Eagle_ lay a little above Staten Island, with their broadsides trained on the doomed city. In the mouth of the North River, not a biscuit-toss from the Battery, floated the brass conning-tower of an American submarine.