572 BELL SYSTEM TECHNICAL JOURNAL 



4. Use of Two Lines for a Portion of the Route 



The circuit shown above enables us to switch two-way transmission 

 from a single line to a pair of lines and vice versa, since any amount 

 of line may bie inserted at BBBB. In connection with these lines any 

 number of additional one-way repeaters may be inserted. The 

 operation of the system is left unchanged beyond the change in the 

 effective amplification which is equal to the difference between the re- 

 peater amplification and the attenuation of the inserted line. In case 

 the total attenuation of the pair of lines exceeds the total amplification 

 of all the repeaters at every frequency the system cannot sing whatever 

 lines be connected at the ends. Practical applications will hinge upon 

 the possibility of securing good quality from a number of repeaters 

 used in sequence. 



Suggestions 1 and 2 seem sufficiently promising to warrant some 

 experimental work at an early date. 



I am preparing a discussion of the general repeater circuit including 

 any number of repeating elements and shall present the theoretical 

 deductions applicable to the above suggestions in that memorandum. 



