NEW YORK-CHICAGO CABLE 73 



arranged in concentric layers as shown and great care and skill are 

 required in the design and manufacture or there is certain to be serious 

 cross-talk between the several hundred circiiits when used for long- 

 distance service. Even after the application of the best present manu- 

 facturing methods, tests are made on all circuits at three points in 

 each loading section of 6000 feet while the cable is being spliced. 

 These tests are made in order to determine the best possible arrange- 



Phantcm Circuit 



Side Circuit n 



Fig. 14 — General Phantom Circuit Arrangement. Four wires providing three circuits 



ment of conductors for still further reducing cross-talk between circuits, 

 and the splicing is done accordingly. 



There are 19 quads of No. 16 A. W. G. and 120 quads of No. 19 

 A. W. G. pure copper conductors in one of the principal sections, and 

 the arrangement of the four wires in each quad is such that two physi- 

 cal circuits and one phantom circuit are made available. The method 

 of obtaining three telephone circuits from two pairs of wires is old and 

 extensively used. It is illustrated in Fig. 14. The method results 

 in a 50 per cent increase in the number of available circuits and its 

 application to this project is therefore of very great economic impor- 

 tance. Now the total of 139 quads multiplied by 3 gives 417 circuits 

 or as many as could be carried on about 14 heavily loaded pole lines 

 if aerial wire were used, but as will be described later, we will have to 

 use two of these circuits to make one telephone circuit in some cases 

 where the distances are comparatively great, so it is expected that 

 only about 300 telephone circuits will be obtained for regular service. 

 This is as many as could be carried on 10 heavily loaded pole lines if 

 aerial wire were used. It is now thought that in some sections this 

 number of circuits will take care of future demands for about 10 years 

 after allowing for the dismantling of some existing aerial wire. 



As these cables can be obtained in any size desired up to the maxi- 

 mum, the period for which they should be engineered can be determined 

 from studies of circuit requirements and costs. These studies are of 

 very great importance and the cost considerations include, of course, 



