Page:Popular Science Monthly Volume 88.djvu/837

 Popular Science Monthly

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��sinks out of sight. It is safe for the moment. The agonizing uncertainty of the crew can be imagined. They know that a relentless enemy awaits them, that his searchlights sweep the water all night. Hour after hour drifts by. If the submarine's commander rises, a hail of shot and shell is sure to rain upon him; if he stays under water very long he and his men will die of suffocation. Why not move on? The waiting motor- boat cannot see him. But in what direction and how far? He is almost sure to run into the shore and to puncture the thin shell that saves him from inundation. If he could only locate the harbor entrance he would be safe. An oscillator and a set of microphones will enable him to head for the inlet as surely as if he were traveling on the surface and he could see it with his eyes. He pulls the switch of the oscillator. A shrill note is sent through the water. His eyes on the steering indicator dial, he watches the response of the finger to an echo. The echo of what? Of the oscillator's vibrations reflected by the shore. He steers this way, now that way, barely crawling along, always watching for the echo on the dial. The finger on the steering indicator moves from side to side as the microphones pick up the echoes. At last there comes a moment when the finger stays at zero, when, in other words, there is no echo for the microphones to hear. That can mean only one thing: the oscillator is sending out its bleat not toward an echoing shore, but toward the har- bor's mouth and toward the open sea, where safety lies. With his eye on the steering indicator the commander sig- nals "full speed ahead," know- ing that salvation lies before him.

Artificial Senses Take the Place of Eyes and Ears

The use of microphones on submarines not only increases the effectiveness of the sub- marine enormously, but opens up new and intensely dramat- ic possibilities. As soon as one submarine is equipped

��with devices for threading a course underwater with certainty all submarines will be similarly equipped. Grant that and at once we have the means of pitting submarine against submarine, of actually engaging in submarine fights. What strange encounters they will be — these underwater engagements of the future! Two vessels, blind but for steering -indicators connected with micro- phones, circling around each other in the effort to ram or to plant a torpedo at the right moment, cocking electrical ears, as it were, and maneuvering entirely by sound — what battle of Wells or of Verne's can compare with it? Instru- ments, artificial senses, take the place of Nature's eyes and ears; hidden move- ments are electrically translated into twitches of a quivering finger on a graduated dial; one intelligence is pitted against' another. Surely this is real scientific warfare — this battle of micro- phones!

A Sewer Banquet at $25 a Plate

TO celebrate the completion of a new sewer in St. Louis a cabaret banquet was held in the tube. A "banquet room" three hundred feet long and a gas- equipped kitchen were created. The food was cooked in the tunnel and served on twelve tables placed lengthwise.

The cost of the banquet was twenty- five dollars a plate.

���The underground kitchen in which the meal for a banquet given in St. Louis' new sewer was cooked

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