306 



BELL SYSTEM TECHNICAL JOURNAL 



static lines will be communicated to the wires, thereby providing a dis- 

 tribution roughly like that shown in Fig. 6.2-1 (b). Except at the moment of 

 contact, there is no motion of the lines of electric force and therefore no 

 magnetic field and, accordingly, there can be no flow of power. The final 

 configuration is to be regarded as the resultant of the forces of tension and 

 lateral pressure. The electric intensity, E, measured in volts per meter at 

 any point along the line, may be altered at will, merely by changing the 

 spacing. 



If, next, we close the remote end of the line by substituting a conducting 

 wire for the particular line of force shown as a heavy line in Fig. 6.2-1 (c), 

 the adjacent lines of electric force will collapse on the terminating conductor, 



Fig. 6.2-1. Lines-of-force conccj)! ;i|)])lic(l to ihe transmission of d-c power along a wire line- 



as opposing charges unite. This removes the lateral pressure on the neighbor- 

 ing lines with the result that the whole assemblage starts moving forward. 

 Each line of force meets in its turn the fate of its forerunners, therel)y de- 

 livering up its energy to the resistance as heat. As soon as the lateral pressure 

 at the cell is relieved, chemical equilibrium is momentarily destroyed and 

 more lines of force are manufactured to fill the gaps of those that have gone 

 before. All of this is, of course, at the exj)ense of chemical action. 



According to the electromagnetic theory, as set forth in the second prin- 

 ciple, this is but a i)art of the stor}- of transmission. We must add that the 

 motion of the lines of electric force from the dry cell toward the resistance 

 gives rise in the surrounding space to lines of magnetic force in accordance 



