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ture to the foregoing, when the vacuum 

 tube is employed as a wireless tele- 

 phone. Hundreds of the bulbs are con- 

 nected to a powerful battery or dyna- 

 mo. The voice spoken into a telephone 

 transmitter connected in the circuit 

 so disturbs the electrical balance of the 

 bulbs that powerful waves are created. 

 The most striking example of this ap- 

 plication was the recent feat of tele- 

 phoning wirelessly from Washington 

 to Hawaii. 



Another use of the audion is in re- 

 laying the current that carries the 



Popular Sciejire Monthly 



By the combination of some of the 

 foregoing properties of the vacuum 

 bulb, the uncanny but delightful result, 

 electrical music, is attained. The idea 

 of converting the silently flowing elec- 

 tric current into strains of the most 

 bewitching music is not entirely new. 

 Many readers will recall the telhar-- 

 monium, which was built at great cost 

 several years ago and with which elec- 

 trical concerts in the home were prophe- 

 sied. But the telharmonium required 

 dynamos of such variety and size that 

 it was eventually given up because of 



In appearance the audion closely resembles an ordinary electric lamp bulb. Euilt into 



the bulb close to the filament are two metal electrodes which are connected in such a 



way that a perfect electrical balance is maintained between them. When the wireless 



wave disturbs this balance, the disturbance is heard in the telephone receivers 



voice over long distance telephone 

 lines. 



The other applications of the audion 

 are of a laboratory nature. One of 

 these applications is transforming elec- 

 tricity. By throwing a small lever, the 

 outgoing current can be varied from 

 fifty to more than a million vibrations 

 a second. 



the prohibitive cost. Music from elec- 

 tricity — or music from light, to be 

 exact— goes back many years before 

 the telharmonium. Legendary Egyp- 

 tian history, three thousand years old, 

 tells us that the rays of the descending 

 sun, would strike w^eird music from 

 the face of the statue of Memnon. 

 Incredible as this tale may seem to 



