524 BEl.L SYSTEM TECHNICAL JOURNAL 



SpixiFic Projects Illustrating Telephone Encineering 

 Problems 



Enough has been said, I bche\e, in the foregoing to indicate the 

 general nature of the engineering problems handled in the Bell System. 

 It is, of course, impracticable and doubtless would be tiresome in a 

 talk of this character to deal specifically with many detailed engineei- 

 ing problems in\ol\-ed in the work which I have just described in 

 general terms. I believe that you will gather a better appreciation 

 of what some of these problems are from the inspection trips which 

 form an important part of this week's program, than you could by a full 

 discussion of them here. It will probably be of interest, however, 

 before closing to outline briefly one or two typical telephone engineer- 

 ing problems of considerable magnitude. 



.\i;\\ \'()RK-C"iiicA(i() Toll Carle 



The first large engineering problem I will consider is that relating 

 to the New York-Chicago toll cable as shown in Fig. 1. This cable 

 follows a route from New York through Harrisburg, Pittsburg, New- 

 castle, Cle\'eland, antl thence to Toledo, and when completed' will 

 extend to South Bend and then on to Chicago. For parts of the 

 distance through the congested sections it is underground, and through 

 the open country it is aerial. 



I'litil a comparati\-ely few years ago practically ail long toll circuits 

 were in open wire construction; that is, individual wires mounted on 

 separate insulators attached to cross-arms on poles. This was a 

 natural development at first, due to the small number of circuits 

 usually involved, but was also necessary because of the relatively high 

 transmission losses of cable circuits where, as you know, the wires are 

 insulated b\' wrappings of paper, closely twisted together in pairs and 

 quads, and large numbers of the.se compressed together within a lead 

 sheath. The rapidly increasing use of toll service, however, pointed 

 to difficulties in pro\iding for future growth with open wire lines. In 

 different parts of the route between Chicago and New York, for 

 example, there were three and four heavily loaded open wire toll lines 

 and the rate of growth was so rapid it was evident that before long 

 dilTiculty would be experienced in obtaining suitable routes for llu- 

 addilitjnal [jole lines required. 



Early efforts were accordingly made to de\ise means which would 

 permit of satisfactory talks through cable and as a result of very 

 intensive research there were developed satisfactor>- forms of telephone 

 ' This cable has recently been completed. 



