Excited in Air at the Foot of Waterfalls. 



421 



about 20 centimetres long, closed at one end and having a bell- 

 shaped opening at the other. Into this tube an ebonite rod 

 was screwed which could be easily removed when it was 

 necessary to renew its surface. Hooks fastened to the tube 

 and to the ebonite rod provided for the support of the insu- 

 lator and the suspension of the wire. 



Kk. 1. 



Fig. 2. 



In the experiments at the foot of the Falls, it was found 

 that with these insulators a wire could be easily maintained 

 at a potential of 10,000 volts for hours even in a drenching 

 spray. 



The exposed wire was tested for induced radioactivity by 

 means of the apparatus shown in fig. 2. A is a galvanized iron 

 cylinder about 30 cms. high and 20 cms. in diameter, resting 

 on an insulated platform and having a movable cover pro- 

 vided with a flanged opening into which was fitted an ebonite 

 plug about five centimetres in diameter. A brass tube C 

 was passed through this plug and into it a second ebonite plug 

 was tightly fitted. This second plug carried a brass rod D 

 from which B a brass reel was suspended, and on this reel 



Phil. Mag. S. 6. Vol. 5. No. 28. April 1903. 2 F 



