ELECTRIC OSCILLATIONS AND ELECTRIC WAVES. 265 



across the gap g and the discharge surges back and forth along 

 the rods until the energy of the charge is dissipated. 



The resonator. The elec- 

 tric waves were detected in 

 Hertz's original experiments 

 by means of an arrangement 

 similar to the oscillator, but 

 with a shorter spark gap and 

 without connections to an in- ^ 



duction coil. This arrange- 

 ment, which is called the resonator, has the same period of oscil- 

 lation as the oscillator so that the action upon it of the train of 

 waves from the oscillator is cumulative, causing it to oscillate in 

 sympathy with the oscillator just as one tuning fork vibrates in 

 unison with a similar one which is set vibrating with a hammer 

 blow. The oscillations of the resonator were indicated by 

 minute sparks in its gap g, Fig. 198. 



The reflectors. The waves which emanate from the Hertz 

 oscillator are very weak at any considerable distance, and their 

 action upon the resonator may be greatly intensified by the use 

 of parabolic reflectors. The oscillator and the resonator were 



oscillator 



to coil 



to coil 



t 



resonator 



.resonator 



