TRANSMISSION DATA FOR RATING TELEPHONE CIRCUITS 339 



two important facts are evident: (1) the curves are practically straight 

 over the more important range (solid lines in Fig. 4), and (2) the 

 straight parts of the curves are practically parallel. For trunks which 



3 4 5 



TRUNK LENGTH IN MILES 



Fig. 4 — Effective trunk and terminal junction losses. 



are electrically short the straight line relation does not hold, but in 

 most cases the exact loss of such short trunks is relatively unimportant. 

 It is possible, therefore, to describe the loss of a particular type of 

 trunk over a wide range of conditions in terms of a series of linear 

 equations all having the same slope but with intercepts which depend 



