ARTIFICIAL LINES FOR CONTINUOUS CURRENTS 

 IN THE STEADY STATE. 



By A. E. Kennelly. 

 Received August 26, 1908. 



Artificial lines are well known to electrical engineers, in telegraphy 

 and telephony, as devices for electrically imitating actual lines of com- 

 munication in a compact and convenient manner. They are employed 

 industrially in most duplex or quadruplex systems. They are also 

 employed in the laboratory for testing methods of telegraphing, or of 

 telephoning, under conditions that are electrically akin to those of 

 practice. 



Artificial telegraph lines contain associated resistance and capacity. 

 Those used in telephony are sometimes provided with inductance and 

 leakance in addition. These quantities are rarely associated distribu- 

 tively, as in actual lines. 1 They are associated for convenience and 

 economy in lumps or sections. Thus an artificial telegraph line con- 

 taining resistance and capacity AE, Figure 1, may be composed of 

 say four similar sections of resistance AB, BC, CD, and DE, each 

 representing the resistance of say 50 miles (or kilometers) of line. 

 Each section is provided at its centre with a condenser having a capac- 

 ity of 50 miles of line. The whole line AE will thus purport to rep- 

 resent 200 miles of line. The imitation must, however, be necessarily 

 imperfect, by reason of the lumpiness of the capacity, which is divided 

 into four blocks, and connected to the line at four points only, instead 

 of being distributed uniformly; i. e., indefinitely subdivided, and con- 

 nected at an infinite number of points, as in the actual line. The 

 smaller the number of sections in the artificial line, the easier and 

 cheaper it will be to build, but the lumpier and more imperfect the 

 imitation will be. The question arises, therefore, as to what are the 

 comparative electrical behaviors of the artificial line and of the line 

 imitated, under any set of assigned conditions. 



1 An exception is found, however, in the artificial lines for duplexing 

 long submarine cables, where the proper proportions of resistance and capa- 

 city are associated distributively. 

 vol. xliv. — 7 



