hy a Charged Condenser moving through Space. 155 



Section 3. The Apparatus and the Experiment. 



After performing several experiments with a preliminary 



apparatus consisting of a single coil rotating between two 



condenser-plates, the form of apparatus shown in fig. 3 was 



finally decided upon. Instead of one rotating coil there 

 were two, each wound with about 300 turns of copper wire 

 to a resistance of 36 ohms, the coils being afterwards bound 



