Page:Popular Science Monthly Volume 89.djvu/17

 Popular Science Monthly

��Vol. S9 No. 1

��239 Fourth Ave., New York

J III II, 1910

��$1..50 Annually

��The Mine That Hears

\\\ Edwunl F. Chandler

It is unnecessary to introduce Mr. Chandler to the readers of the Popi lar Science Monthly. In the present article he describes another one of his remark- able applications of the microphone to naval weapons — an application li-hich is based upon a ripe experience gained in the drcelopment of torpedoes and other inventions. The "Mine that Hears" is the result of sei'eral years of constant study and experiment by the author, and is described here in detail for the first time. — Editor.

��E\'KR\' one knows that in time <jf war harbors are protected by mines through which an enemy cannot easily pass without the risk of cicstro\ing himself. Depending on their nature the mines are called "contact" or "shore- controlled." As the names indicate, the contact mine c\plf)des as soon as a trigger with which it is provided is actuated by a ship, or a bottle of acid is spilled on a suitable chemical; the shore-controlled mine is exploded elec- trically from a station at the critical moment determined by obserxation.

Of the two kinds the shore-controlled is the safer. The contact-mine may break loose and become a menace to neutral shipping, as the tragic incidents of the present war ha\e abundanth' shown.

The British Grand Fleet undoubtedh- owes its safety in part to the submarine mine. It lies in harbors the entrances of which are sown with mines .so thickh' that a sul)niarinc could not worm its way through them without blowing itself up. Whether or not the feat of running through a mine-field has actually been performed in the war there is at least reason to believe that it has been attempted. Mr. Simon Lake, a leading authority on submarine boat construction in this country, not only declares that a submarine can

��penetrate a mine-held but has slicjwn how it can be done. He has devi.sed a special type of submarine provided with an antennalikc projection or "feeler" in front, which enables a submarine com- mander to push aside mines with reasonable safety.

If the Lake and similar systems are able to perform their functions it is ob\ious that no harbor is absoluteh- safe from submarines. In previous articles published in the Poil'I-.ar Science ^Ionthlv, I have shown how- torpedoes can be automatically steered toward ships, which they are intended to destro\', by employing microphones to pick up the propeller \ibrations, and how submarine boats, which are notori- ously blind under water, can be directed accurately toward a hostile vessel b\' the same means. I ha\e worked out a method of applying microphones to mines, which, it seems to ine, makes it quite impossible for a submarine to enter a mine-sown harbor, and which also enables the othcer in command of a station from whic-h shore-controlled mines arc fired to detect the attempt of a surface vessel to enter under the cloak of a dense fog.

The system which I have devisefl would render it possible to blow up .i submarine trying to worm its wa\' into a mine-protected harbor, or a battleship