Popular science monthly . on specific conversation asto their ships positions and the danger ofbiniiping into each other or into objectson shore, the wireless signals them-selves carry no warning of impendingdisasters; the strength of wireless sig-nals, as received, is no criterion of thesending ve-ssels distance. Hence when a fog descends over thesea, light signals are utterly useless,sound signals in air do not carry far andare uncertain, and wireless telegraphy isgood onl\- in certain instances. Is it anywonder that inxenlors have taken toiiixestigating the possibilities of sub-marine signa
Popular science monthly . on specific conversation asto their ships positions and the danger ofbiniiping into each other or into objectson shore, the wireless signals them-selves carry no warning of impendingdisasters; the strength of wireless sig-nals, as received, is no criterion of thesending ve-ssels distance. Hence when a fog descends over thesea, light signals are utterly useless,sound signals in air do not carry far andare uncertain, and wireless telegraphy isgood onl\- in certain instances. Is it anywonder that inxenlors have taken toiiixestigating the possibilities of sub-marine signaling, all the more since theyhave discovered that sountl-signals willcarr\- long distances under water and areunalTected by fogs and storms? Popular Science Monflihi 713 by it can be made to have anysustained duration desired,so long as the felt-rimmedwheel rubs on the steel strip —T FOUR I RON CROSS-PIECES WHICH BRACEHULL AROUND VI-BRATING STRIP ANDPREVENT HULL PLATESFROM SETTING UPINTERFERING VI-BRATIONS OF THEIRrOWN. It is a queer world, this—down underthe sea. It might be supposed that nosounds at all can be heard under opposite is true. Sounds carrybetter in a dense medium like water thanin a comparativeh thin gas such asair. All sorts of sounds can be heardunder water—the throb of some distantships propeller, the pounding of engines,the explosion of distant mines, andhundreds of other noises. A micro-phone, placed in a chamber of water atthe side of the receiving vessel and con-nected with a telephone receiver, aids inthis hearing. Singhalese fishermen, how-e\er, have for centuries carried on com-munication between boats by the simplemethod of striking an earthen bowlunder water, the listening fisherman Vibrations from the interior ships hull do not interfere with the signals placing his ear against the bare hullof his boat. Submarine bells are already in useas fog warnings. Some attempt hasbeen made to adapt them to the send-ing of Morse telegraph signals
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectscience, bookyear1872
