36 GENERAL THEOREMS. 



CHAPTER III. 

 GENERAL THEOREMS. 



45. EMISSION AND ABSORPTION OF FORCE BY ELECTRICAL 

 MASSES. The flow of force through an orthogonal tube remains 

 constant, as we have seen (35), so long as the tube does not 

 encounter any acting mass ; the direction of the transmission is 

 that in which the potential diminishes. 



If the tube encounters a mass of electricity m, the flow of force 

 experiences an increase qxm at the boundary, which it retains 

 beyond it as long as the tube does not encounter fresh masses. If 

 the mass thus encountered is on the surface of a conductor, it is 

 such as will reduce to zero the flow of force transmitted by the 

 tube. We may then say that of two corresponding elements dS 

 and dS', whose densities are a- and o-', the positive electricity of the 

 element dS emits a flow of force 471-07/8, which at the other end 

 of the tube is absorbed in the equal quantity of negative electricity 

 or) the element dS'. 



On Faraday's views there are no unlimited tubes of force. A 

 tube proceeding from an electrified body would always terminate 

 somewhere on another body, so as to induce on the corresponding 

 element an equal quantity of electricity of the opposite sign. On 

 this view, there could nowhere be an absolute and independent 

 quantity of electricity which has not its complementary quantity at 

 the other end of the tube. 



No line of force can exist between two points charged with the 

 same electricity. Nor can there be any between two points at the 

 same potential. In fact, no line of force can correspond on a 

 conductor to a point not charged with electricity (36). 



46. THE POTENTIAL CAN NEITHER HAVE A MAXIMUM NOR A 

 MINIMUM OUTSIDE THE ACTING MASSES. An insulated mass m 

 concentrated in a point may be regarded as a layer spread over a 

 very small conductor. If the mass m is positive, the point A, which 



