Fatigue and Recovery of the Fhoto-Electric Current 3 



EXPERIMENTAL ARRANGEMENT 



Figure i presents a diagram of the system used. An electric 

 arc. A, operated in parallel with a capacity, K, by an induction coil 

 fed by a fifty-volt alternating current, served as source of light. 

 This arc was focused by a quartz lens, L, through a window, Q, 

 of same material on the cathode. £, charged from a battery, B. 



WQ> 



The current of negative electricity from E to the anode, H, 

 placed opposite, was determined by measuring the rate with which 

 a definite capacity, C„ connected to the latter, was charged. For 

 this purpose a Thomson quadrant electrometer was employed in 

 the customary manner. The positive pole of the battery and the 



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