122 POPULAR SCIENCE MONTHLY. 



discharging the condenser across the spark gap so as to create altera- 

 tions of potential at some point on the oscillation circuit. The length 

 of the aerial must then be so proportioned as above described that it is 

 resonant to this frequency. Thirdly, we may employ the arrangement 

 involving an oscillation transformer, in which the oscillations in the 

 primary condenser circuit are made to induce others in the aerial circuit, 

 the time-period of the two circuits being the same. This method may 

 be called the Braun-Marconi method. Professor Slaby has combined 

 together in a certain way the original Marconi simple aerial with the 

 resonant quarter-wave-length wire of Braun. He constructs what he 

 calls a multiplicator, which is really a wire wound into a loose spiral 

 connected at one point to an oscillation circuit consisting of a con- 

 denser inductance, the length of this wire being proportioned so that 

 there is a great resonance or multiplication of tension or potential at 

 its free end. This free end is then attached to the lower end of an 

 ordinary Marconi aerial, and serves to charge it with a higher potential 

 than could be obtained by the use of the induction coil directly attached 

 to it. 



(To he continued.) 



