Popular Science Monthly 



809 



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 



