MISCELLANEOUS PRACTICAL APPLICATIONS. 



329 



as follows : At the instant a battery is connected to a cable a very 

 large current begins to flow into the cable. Most of this current 

 goes to charge the cable, and, as the cable becomes charged, the 

 entering current falls off in value, settling finally to a steady value 

 which is determined by the resistance of a cable. The ordinates 

 of curve A in Fig. 3 I show the successive values of the current 

 which enters a cable from a battery. At the distant end of 

 the cable an infinitesimal current begins almost at the instant 

 the battery is connected at the sending station, and, as the cable 

 becomes charged, this current rises in value until it reaches a 

 steady value very nearly equal to the steady value of the enter- 

 ing current. The curve B, Fig. 31, shows the growth of cur- 

 rent at the distant end of a cable when a battery is connected to 

 the near end. When the battery is disconnected the current 

 which enters the cable ceases at once, and the current at the dis- 

 tant end drops slowly to zero as the accumulated charge flows out 

 of the cable. 



Distortion of current pulses by a cable. The curve a, Fig. 32, 

 shows the character of the current pulse which enters a cable when 



TIME 



Fig. 32. 



a battery is momentarily connected to the cable, and the curve b 

 shows the character of the current pulse which flows out at the 

 distant end of the cable. The action of a cable in thus alter- 



