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 



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