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DR. HAROLD A. WILSON ON THE ELECTRIC EFFECT OF 



The apparatus was first set up in October, 1903, and the existence of the effect 

 was almost immediately discovered. Various disturbing causes prevented accurate 

 measurements being made, but these were ultimately nearly got rid of by suitable 

 modifications of the apparatus. The apparatus described below is the final form 



Fig. 1. A A, phosphor bronze axle; BB, ebonite cylinder; CC, brass tube; DD, brass tube; 

 EE, vulcanised fibre tube ; FF, revolution counter disk ; PP, driving pulley. 



adopted, with which it was found possible to make measurements of the induced 

 electromotive force. 



The dielectric cylinder used in the experiments was of ebonite, 9 '97 centims. long, 

 4 '15 centims. outside diameter, and 2*01 centims. inside diameter. It was mounted 

 on a phosphor bronze axle, as shown in fig. 1, which is drawn to scale. 



Fig. 2. AAAA, steel casting; BB, ebonite cylinder; CCCC, steel screws with cones; E, F, brushes ; 

 HH, rod supporting revolution counter; JJ, plates closing end of solenoid; KK', ebonite blocks 

 supporting brushes ; LL, tubes for water jacket ; M, revolution counter wheel ; XNNN, lock nuts ; 

 P, driving pulley; SSSS, magnetising solenoid ; WWWW, water jacket. 



The tube DD was insulated from the axle by the tube EE of vulcanised fibre. 

 The tube DD was connected to earth during the experiments by a sliding contact 



