PRESENT PROBLEMS 93 



inductors are therefore so charged as to produce this uniform poten- 

 tial in the presence of these charged inductors, and the polarized 

 glass of the rotor. The ends of the conductor are therefore oppositely 

 charged. There is on its surface a neutral line of no charge. During 

 the motion of the rotor these opposite charges are oppositely directed 

 in the conductor. They are continually being added together. Equal 

 quantities of unlike signs are continually being added together. Are 

 we to assume that equal currents of unlike signs are superposed? Is 

 a positive current in a positive direction identical with a negative 

 current in a negative direction? Mathematically we should say yes. 

 The resulting current, moreover, is uniform throughout the circuit, 

 when measured by its external electromagnetic effects. We may loop 

 in calibrated galvanometers at any point in the circuit, and they tell 

 the same story. But what do the results of Rowland and Rutherford 

 teach us? The ft particles carry the negative charge. The negative 

 charge is part and parcel of something which has a positive mass. 

 The a particles are perhaps a combination of more ft particles in 

 combination with other particles having (or being) a positive charge 

 of greater numerical value. We have found long ago that the pro- 

 ducts of an explosion are not necessarily composed of matter in its 

 most elementary form. But these a particles are also part and parcel 

 of something which has a positive mass. 



Are we to think of this conductor as being the seat of some action 

 by which positive masses are being urged in a positive direction and 

 positive masses are also being urged in an opposite direction? Are 

 we to think that the mass of such a conductor, carrying a direct cur- 

 rent, is slowly increasing, and that after many thousands of years this 

 increase will become appreciable, resulting, perhaps, in a clogging of 

 the conductor, and a decrease in its conduction? In that case a cur- 

 rent of positive electricity moving in a positive direction is not a 

 current of negative electricity moving in a negative direction. In 

 that case the nature of positive and negative currents of electricity 

 flowing in opposite directions is fundamentally different from that 

 of the flow of heat and cold in opposite directions, for it involves 

 the motion of masses in opposite directions. It would be interesting 

 to examine whether the long-continued use of a conductor carrying 

 a continuous current may not result in conferring upon it radioactive 

 properties. The results of J. J. Thomson 1 on the phenomena shown 

 by a Geissler tube 15 meters in length are very significant in this con- 

 nection. He finds the positive luminescence to travel in a direction 

 opposite to that of the cathode stream in the Crookes tube, with a 

 velocity somewhat more than half that of light. The older results of 

 Wheatstone 2 also show that the current from a Leyden jar travels in 



1 Recent Researches in Electricity and Magnetism, p. 116. 



2 Phil. Trans., Royal Society, London, 1834. 



