And so the ninety-mile journey down Long Island Sound, partly under water, partly on the surface, to New York, was completed.  The greater voyage to the Delaware Capes followed, and at all times the little sixty-three-foot boat that was but eleven feet in diameter at her greatest girth carried her crew and equipment with perfect safety and without the least inconvenience.

Such a vessel, small in size but great in destructive power, is a force to be reckoned with by the most powerful battle-ship.  No defense has yet been devised that will ward off the deadly sting of the submarine’s torpedo, delivered as it is from beneath, out of the sight and hearing of the doomed ships’ crews, and exploded against a portion of the hull that cannot be adequately protected by armour.

Though the conning-dome of a submarine presents a very small target, its appearance above water shows her position and gives warning of her approach.  To avoid this tell-tale an instrument called a periscope has been invented, which looks like a bottle on the end of a tube; this has lenses and mirrors that reflect into the interior of the submarine whatever shows above water.  The bottle part projects above, while the tube penetrates the interior.

[Illustration:  SPEEDING AT THE RATE OF 102-3/4 MILES AN HOUR]

The very unexpectedness of the submarine’s attack, the mere knowledge that they are in the vicinity of a fleet and may launch their deadly missiles at any time, is enough to break down the nerves of the strongest and eventually throw into a panic the bravest crew.

That the crews of the war-ships will have to undergo the strain of submarine attack in the next naval war is almost sure.  All the great nations of the world have built fleets of submarines or are preparing to do so.

In the development of under-water fighting-craft France leads, as she has the largest fleet and was the first to encourage the designing and building of them.  But it was David Bushnell that invented and built the first practical working submarine boat, and in point of efficiency and practical working under service conditions in actual readiness for hostile action the American boats excel to-day.

A PEACEFUL SUBMARINE

Under the green sea, in the total darkness of the great depths and the yellowish-green of the shallows of the oceans, with the seaweeds waving their fronds about their barnacle-encrusted timbers and the creatures of the deep playing in and about the decks and rotted rigging, lie hundreds of wrecks.  Many a splendid ship with a valuable cargo has gone down off a dangerous coast; many a hoard of gold or silver, gathered with infinite pains from the far corners of the earth, lies intact in decaying strong boxes on the bottom of the sea.