Vlll CONTENTS. 



CHAPTER VII. 

 ELECTRIC GENERATORS. 



THE ELECTROPHORUS AND FRICTIONAL MACHINE, 92 



CHAPTER VIII. 

 ELECTRIC GENERATORS. 



THE HOLTZ AND TOPLER MACHINES, . . . 108 



CHAPTER IX. 

 EXPERIMENTS WITH THE TOPLER MACHINE, . . . 125 



CHAPTER X. 

 ELECTRIC TRANSMISSION IN VACUA, .... 146 



CHAPTER XI. 

 ELECTROMETERS, 155 



CHAPTER XII. 

 THE ELECTRICITY OF THE EARTH AND ATMOSPHERE. 



POTENTIAL AND EARTH CURRENTS, . . . 175 



CHAPTER XIII. 

 THE ELECTRICITY OF THE EARTH AND ATMOSPHERE. 



THE AURORA, 190 



CHAPTER XIV. 

 THE ELECTRICITY OF THE EARTH AND ATMOSPHERE. 



LIGHTNING AND THUNDER, 207 



