46 



BELL SYSTEM TECHNICAL JOURNAL 



cable, open wire and carrier and the expected increase of each during 

 the next four years is shown in Fig. 36. 



Open Wire and Carrier Circuits 



The standard construction for open wire telephone circuits in the 

 United States is indicated by the diagram of Fig. 37 and a typical 

 pole line built in accordance with this construction is shown in Fig. 38. 



3-C 3-C BH 3-C 3-C 



PH r. -.., PH 



&V& &V& srioi e^e""d"va 



l-C 



PH 



l-C 



&v & & V & 



T 13 T j Jp T 



l-C 



PH 



l-C 



3J 



6 Cr ti" vO 



l-C l-C 



PH 



& v""8""'""&"^v a iff^&j f\ v"g"""""ff"v fl 



Fig. 37 — Pole Line Configuration, phantomed construction, 

 12 inch spacing between wires of non-pole pairs. 



The wires are of copper and the sizes and weights are shown in the 

 following table. 



Diameter — mm. 



2.6 

 3.2 



4.2 



Weights — kg. per km. 



47 



74 



118 



Bronze and aluminum are not, in general, used in the United States 

 for telephone lines, being not as economical or as generally satis- 



