Electric Resonators 345 



celebrated experiments of Hertz, which in turn have 

 formed the point of departure for wireless telegraphy. 



It is known also that such an electric resonator has 

 been rightly compared to a vibrating dynamic system, to 

 a pendulum which has an oscillation time of its own, to a 

 sounding chord which the smallest impulses having the 

 same frequence as itself can set in vibration, even in 

 strong vibration. What happens in it is a continual 

 periodic transformation of energy. At the instant when 

 the sinusoidal alternating current reaches its maximum 

 intensity, one has the maximum of actual energy, while 

 the condenser, on the other hand, possesses then no 

 potential energy whatever. At the instant when the in- 

 tensity of the current drops to nothing, the condenser 

 shows the greatest deformation of the respective di- 

 electric, and possesses thus a potential energy fully equal 

 to the actual energy possessed by the discharge at the 

 moment of its greatest intensity, the process being thus 

 exactly the same as in a pendulum in which potential 

 energy is transformed continually into actual and vice 

 versa. 



It will be sufficient here, for the purpose of a remote 

 comparison, to note the fact just indicated that a sinu- 

 soidal alternating electro-motive force induced in such an 

 electric resonator, which need amount only to a very few 

 volts, provided that it be of the same frequency as the 

 oscillating discharge, will be able to induce in A and B 

 differences of tension which may amount to many volts. 

 For if we assume in the current so oscillating the faculty 

 of depositing in each of the armatures of the condenser 

 infinitely small particles of substance in series one after 

 the other, so long as the total of their mass and the con- 

 sequent electro-motor force does not surpass the electro- 



