Continuity 27 



Electricity itself i. e., electric charge 

 strangely enough has proved itself to be 

 atomic. There' is a natural unit of 

 electric charge, as suspected by Faraday 

 and Maxwell and named by Johnstone 

 Stoney. Some of the electron's visible 

 effects were studied by Crookes in a 

 vacuum; and its weighing and measuring 

 by J. J. Thomson were announced to the 

 British Association meeting at Dover in 

 1899 a striking prelude to the twentieth 

 century. 



An electron is the natural unit of 

 negative electricity, and it may not be 

 long before the natural unit of positive 

 electricity is found too. But concerning 

 the nature of the positive unit there is at 

 present some division into opposite camps. 

 One school prefers to regard the unit of 

 positive electricity as a homogeneous 

 sphere, the size of an atom, in which elec- 

 trons revolve in simple harmonic orbits 

 and constitute nearly the whole effective 

 mass. Another school, while appreci- 

 ating the simplicity and ingenuity and 

 beauty of the details of this conception, 



