1902.] on Musical and Talking Electric Arcs. 71 



out of action) be used as the self-induction in the shunt circuit, then 

 a high frequency flame discharge can be obtained from the secondary. 

 Using a spark gap and Tesla coil in the ordinary way and supplying 

 it from the secondary of the above induction coil all the ordinary 

 Tesla phenomena can be produced. This experiment is of scientific 

 interest, in that, without the use of a high frequency alternator or of 

 any mechanically moving parts, low voltage direct current is converted 

 in two steps into high voltage and very high frequency Tesla 

 currents. Each step consists of the use of an electrically unstable 

 conductor, the arc in one case the spark in the second, in conjunction 

 with a circuit in which oscillations can take place. The first step 

 converts the harmless direct current into dangerous high potential 

 current ; the second step of the transformation, by still further raising 

 the voltage and the frequency, again renders it harmless to human 

 beings. 



Magnetic space telegraphy can be very well demonstrated by 

 using the self-induction coil in the oscillatory circuit as the 

 transmitter. The efiect of tuning the receiving circuit to the same 

 note as the transmitter can be well illustrated. For instance, if a 

 small incandescent lamp be used as the indicator in the receiving 

 circuit, it is easy to so tune it to correspond with one note in the 

 octave that the lamp will light up brightly when this note is sounded, 

 will only just glow red if the next note higher or lower is depressed, 

 and will not light at all for any other note ; so that if a scale or tune 

 be played on the musical arc, the lamp in the receiving circuit will 

 light up brightly every time the note occurs to which the receiving 

 circuit is tuned. It would be quite easy to tune a separate receiving 

 circuit to each of the notes of the octave and so form a system of 

 syntonised wireless telegraphy on a small scale. 



There is no doubt that the commercial success of wireless tele- 

 graphy will largely depend on the perfection of the syntony which 

 can be maintained between the transmitting and receiving stations, as 

 the more perfect the syntony the larger the number of messages 

 which will be able to be transmitted simultaneously, and the longer 

 the distance over which they will be able to be transmitted. So long 

 as the transmitter only sends out trains of waves of decreasing 

 amplitude at regular intervals, as at present, no very perfect syntony 

 can be hoped for. As soon, however, as the transmitter can be 

 supplied continuously with high voltage, high frequency currents of 

 constant amplitude and thereby caused to send waves of a definite 

 constant frequency and amplitude, so soon will very accurate syntony 

 become possible and a great advance in wireless telegraphy and 

 transmission of energy be made. May not the principle of the musical 

 arc render this possible in the future ? 



W. D. 



