110 



Commendatore G, Marconi 



[March 13, 



spark by means of an induction coil. The secondary circuit of 

 the oscillation transformer was inserted between the vertical conductor 

 or aerial wire, and earth, and an adjustable inductance coil included 

 in the circuit. 



The circuits, consisting of the oscillating circuit and radiating 

 circuit, were more or less closely " coupled " by varying the distance 

 between the primary and secondary of the oscillation transformer. 

 By the adjustment of the inductance inserted between the elevated 

 conductor and earth, and by the variation of the capacity of the 

 primary circuit of the oscillation transformer, the two circuits of the 



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transmitter could be l)rought into resonance, a condition which I first 

 found was absolutely necessary in order to obtain efficient radiation. 



The receiver consisted also of a vertical conductor or aerial con- 

 nected to earth through the primary of an oscillation transformer,' the 

 secondary of which included a condenser and a coherer, or other 

 suitable detector, it being necessary that the circuit containing the 

 aerial and the circuit containing the detector should be in resonance 

 with each other, and also in tune with the periodicity of the oscilla- 

 tions transmitted from the sending station. 



The energy employed to signal over a distance of 186 miles could 

 be brought as low as 150 watts, and even less if a higher or larger 

 aerial had been used. 



