Band Concerts from an Electric 



Light Bulb 



M 



By George F. Worts 



USIC that ranges from the pierc- does not stop there. If several of the 

 ing wail of a taut violin string tubes are connected in the correct way 

 to the grumbling bass of a mon- and adjusted with great care, the wire- 



ster horn has been added to the re- 

 markable achievemnts of an electrical 

 instrument so small and so insignifi- 

 cant in appearance that it could be 

 passed by scores of times without 

 arousing so much as a lingering glance. 

 Despite its innocent appearance, 

 however, its technical name is more 



less signals will be increased in loud- 

 ness several hundred times. This ar- 

 rangement is known as the Audion 

 amplifier. 



In both of these uses, the construc- 

 tion and operation of the audion are 

 practically the same. In fact, for all 

 of the uses to which the audion is put. 



than formidable. Scientists know it as its fundamental structure, apart from 

 the "oscillating vacuum tube," al- size, does not vary. In appearance it 

 though this name has been changed closely resembles an ordinary electric 

 and shortened to a simple compound lamp bulb. There is a brass base with 

 word, "audion." "Audion" is derived threads, so that it can be screwed into 

 from audio, to hear, and ion, the tini- a socket, a round glass bulb and a fila- 

 est division of electricity ; in other ment burning brightly in a partial vac- 

 words, to make audible the action of uum. But beyond this point, the an- 

 ions. This, in a word, is exactly what dion and the electric light are strangers, 

 the oscillating vacuum tube accom- Built into the bulb close to the fila- 

 plishes. ment are tw^o metal electrodes. One 

 Before proceeding directly to a dis- is a tiny replica of the grids that are 

 cussion of the latest marvel of the au- used in coal stoves .... and it is called 

 dion, — electrical music — let us pass a grid ; while the other is a small plate 



hurriedly over some of 

 the achievements that 

 have preceded it, 

 which, in a round-about 

 way, have led to the 

 discovery. 



Amateur and profes- 

 sional wireless opera- 

 tors know the audion 

 well, although numbers 

 of them are not aware 

 that it has other uses 

 than the reception of 

 radio signals. 



Connected with the 

 proper wireless instru- 

 ments, the audion will 

 receive and strengthen 

 the weak signals of a 

 distant radio station to 

 a degree several times 

 as loud as any other 

 detector. But its abil- 

 ity in this direction 



Dr. Lee DeForest, inventor 



of electrical music, and his 



audion bulb 



71 



The grid and the plate 

 are connected to the 

 other apparatus in 

 such a way that a per- 

 fect balance, electric- 

 ally speaking, is main- 

 tained between them. 

 When an outer influ- 

 ence, such as an in- 

 coming wireless wave, 

 is brought into the 

 bulb, this balance is 

 disturbed, and in a 

 strengthened form, the 

 disturbance is heard in 

 the telephone head re- 

 ceiv ers a s the dots and 

 dashes of the wireless 

 code. 



Strange to say, this 

 same balancing princi- 

 ple is made use of in 

 another application di- 

 rectly opposite in na- 



