16(3 HOUSTON, KENNELLY THE PATH OF A CURRENT. [Mar. 19, 



netic flux is doubled. In the third passage from A4 to B^, Fig. 38, 

 there is a reappearance of the original electric flux and potential, 

 but with the magnetic flux trebled. In the fourth passage, not 

 shown, there is a disappearance of electric flux with the magnetic 

 flux quadrupled, and so on indefinitely. The current strength, 

 which is always measured by the density of magnetic flux, con- 

 tinually increases by successive leaps at each succeeding passage, but 

 the electric difference of potential between the wires oscillates be- 

 tween the original quantity of 1000 volts and zero. After an in- 

 definitely long period from the start, the current carried by the cir- 

 cuit will be indefinitely great, and this corresponds to what Ohm's 

 law would prescribe in a case of perfect conduction. 



Any actual circuit of perfect insulation but imperfect conduction 

 would differ from this case in the fact that the vanguard would be 

 continually subjected to attenuation and distortion, so that it be-, 

 comes less and less observable in its passage at each successive 

 traverse of the circuit. Finally, after a certain interval of time has 

 elapsed, no further accretion of electric or magnetic flux is per- 

 ceptible. The rate of dissipation of energy taking place into the 

 conductor, all along the circuit, would then be just balanced by the 

 rate at which further flux energy is pouring into the circuit from the 

 generator. This is the condition which is determined by Ohm's 

 law for the case of a definite resistance and perfect insulation. The 

 effect is to lower the pressure to zero at the distant end of the cir- 

 cuit, and to maintain a uniform strength of magnetic flux distribu- 

 tion all through the circuit. Consequently, when the steady state has 

 been attained under the influence of imperfect conduction and perfect 

 insulation, the potential falls steadily from the source towards the 

 distant end, but the magnetic flux-rush is constant throughout. 

 The electric flux-rush is, therefore, also constant at all parts of the 

 circuit, but some of the rush is directed upwards and some of it is 

 directed downwards, so that at the distant end there is no resultant 

 electric flux, while at the generator end the resultant electric flux is 

 at full density. 



This condition is represented in Fig. 39. Here the outrush from 

 the dynamo is indicated by the long flux arrows pointing down- 

 wards. As these reach the BD end of the circuit, they are short- 

 ened in length, to indicate that the flux density has suffered diminu- 

 tion by attenuation on the journey. The reflected stream is then 

 shown by the reversed arrows, which shorten in length as they return 



