His voice had risen as he talked until it had grown vibrant with enthusiasm; and his hands pointed his remarks with quick, sharp gestures.

“All this,” he went on, “was never possible until three years ago, when the navies of the world were given over into the hands of one nation—­my country.  Five years ago a fellow-countryman of mine happened to be present at an electrical exhibition in New York City, and there he witnessed an interesting experiment—­practical demonstration of the fact that a submarine mine may be exploded by the use of the Marconi wireless system.  He was a practical electrician himself, and the idea lingered in his mind.  For two years he experimented, and finally this resulted.”  He picked up the metal spheroid and held it out for their inspection.  “As it stands it is absolutely perfect and gives a world’s supremacy to the Latin countries because it places all the navies of the world at our mercy.  It is a variation of the well-known percussion cap or fuse by which mines and torpedoes are exploded.

“The theory of it is simple, as are the theories of all great inventions; the secret of its construction is known only to its inventor—­a man of whom you never heard.  It is merely that the mechanism of the cap is so delicate that the Marconi wireless waves—­and only those—­will fire the cap.  In other words, this cap is tuned, if I may use the word, to a certain number of vibrations and half-vibrations; a wireless instrument of high power, with a modifying addition which the inventor has added, has only to be set in motion to discharge it at any distance up to twenty-five miles.  High power wireless waves recognize no obstacle, so the explosion of a submarine mine is as easily brought about as would be the explosion of a mine on dry land.  You will readily see its value as a protective agency for our seaports.”

He replaced the spheroid on the table.

“But its chief value is not in that,” he resumed.  “Its chief value to the Latin compact, gentlemen, is that the United States and England are now concluding negotiations, unknown to each other, by which they will protect their seaports by means of mines primed with this cap.  The tuning of the caps which we will use is known only to us; the tuning of the caps which they will use is also known to us!  The addition to the wireless apparatus which they will use is such that they can not, even by accident, explode a mine guarding our seaports; but, on the other hand, the addition to the wireless apparatus which we will use permits of the extreme high charge which will explode their mines.  To make it clearer, we could send a navy against such a city as New York or Liverpool, and explode every mine in front of us as we went; and meanwhile our mines are impervious.