WIRELESS TELEOKAPHV 



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proportion, the e([iiival(Mits ot" iiUH-hiinical iiicrtia, elasticity, aiul resist- 

 ance, in inductance, capacity", and ohniic resistance, respectively; and 

 the rate ot" electric oscillation of a circuit may be yaried by 

 ^'aryino• these factors — the smaller the factors the higher the 

 rate of oscillation. 



When, then, the receiving- circuit of a wireless telegraph 

 system is accurately tuned to oscillate in harmony with the 

 transmitting circuit, which can ])o done by giving the respec- 

 tive circuits practically equal inductance, capacity, and resis- 

 tance, the receiving circuit will respond only to the oscillations 

 set up l)v a transmitter corres]^ondingly tuned. At least, this 

 is, l)rietly, the theory on which these experiments are ])ased. 

 '"") In experimenting, Marconi and others have, it is stated, found 

 ") that perfect syntony between the respective stations is not 



absolutely essential, l)ut that if ther(> is 

 a marked divergence of frcNjuency of 

 oscillation between them the receivers 

 will not respond to any Init their cor- 

 respondingly attuned transmitters. 



The arrangement of Marconi's tuned 

 transmitting and receiving circuits is 

 outlined in tigs. 7 and S. It will there be 

 seen that the oscillator and the coherer 

 /• are not connected to the earth, as in 

 Marconi's first experiments, but arc 

 kept in electrical connection tiierewith 

 by a small induction coil 7'. In tig. 7, .1 is the Acrtical wire, which is 

 attached at its lower end to a coil of wire //'. The end of the wire d 

 which forms part of the secondary wire of the induction coil T, 

 may be connected to any desired turn of the coil /r. By this 

 means the inductance of the vertical wire circuit may be varied, 

 and its oscillation period thereby be made to correspond with 

 that of the circuit y5, of the oscillator, which includes the pri- 

 mary \vire of T; C is an adjustable condenser of very small 

 capacity, ])y varying which the oscillation period of the circuit 



uiay readily l)e varicnl. An 

 electrical condenser is vir- 

 tually a Ley den jar, arranged 

 in a con\-eni(Mit foi-m. In this 

 case it consists of a few siiects 

 of tin foil or copper, th(» alter- 

 nate sheets ])eing se])arated 

 from each other by thin sheets 

 of paraffin paper. A key controls tlu^ storage battery circuit, as 

 shown in tig. 7, and, thereby, the oscillator circuit; J/is the induction 

 coil of the oscillator. 



-Murciiiii's tiiiUMl transmittiuj; 

 circuit. 



Fig. 8. — The tiinod recciviiiu cue uit. 



