138 Rutherford: Modern 



electricity in motion, and was the age of the galvanom- 

 eter and battery and of its successor, the dynamo. As 

 the importance of current electricity became more and 

 more obvious on the theoretical as well as on the purely 

 practical side, the subject of electrostatics, which figured 

 so prominently in the infancy of the subject, fell from 

 its high estate, and there was a tendency as the century 

 advanced to relegate it more and more to the museum 

 of scientific curiosities, as of interest mainly to the anti- 

 quarian, and of no obvious importance to the develop- 

 ment of electricity, except perhaps to serve as mental 

 pabulum for the training of junior students. 



This statement is hardly an exaggeration of the gen- 

 eral attitude of the scientific world to electrostatics 

 twenty years ago. But a great and sudden change soon 

 came to pass. The rapid series of discoveries beginning 

 with the experiments of Hertz on electrical waves in 

 1886, the discovery of X-rays by Rontgen in 1895, of 

 radioactivity by Becquerel in 1896, and the investigation 

 of the discharge of electricity through gases, once more 

 attracted attention to the importance of the fundamental 

 ideas of electrostatics and to the connection between posi- 

 tive and negative electricity. 



No more interesting indication of this rehabilitation 

 of the subject of electrostatics can be shown than the 

 fact that the Leyden jar is now an indispensable adjunct 

 of wireless telegraphy, and that the gold leaf electro- 



