342 



KENNELLY-NABESHIMA— ESTABLISHING A 



alternation of impressed e.m.f., there is an accidental transient 

 ripple, due to a slip in the contact mechanism of the line-switching 

 apparatus at A. This momentary disturbance is clearly duplicated 

 simultaneously at Aig in the sending current. After an interval of 

 about 2 milliseconds, a similar ripple transient appears at Ae,-, in 

 the voltage at B. All of these transients are absorbed in s^, at B, 

 and do not reappear. Such wave transients may be called casual 

 transients, to distinguish them from initiating transients which occur 

 at the starting of an a.-c. regime, or from terminating transients 

 which occur at the opening of an a.-c. circuit. 



Regular Transients with Apparent Distortion. — In the case repre- 

 sented by Fig. 9, the e.m.f. and current waves, launched without 

 appreciable splash, develop regular transients that build into the 

 final steady state, without noticeable distortion. The successive 

 alternations increase in size without departing noticeably from their 

 sinusoidal shape. This is for the reason that the successive reflec- 

 tions, so long as they are of appreciable magnitude, happen to make 

 their appearance, at each end of the line, at or near the moments 

 when the voltage and current are passing through zero. This must 

 always happen, according to theory, when the length of the freed 

 line is a quarter wave for the impressed frequency. If, however, 

 the line has a length distinctly different from a quarter wave, or 



Fig. 13. Apparent Distortion of Transients due to Interference of Suc- 

 cessive Reflections. 



simple multiple thereof ; or if the voltage and current waves are 

 recorded at some intermediate point of a freed quarter-wave line, 

 each of the successive reflections will come in during the active part 

 of an alternation. In particular cases, they may happen to arrive 



