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BELL SYSTEM TECHNICAL JOURNAL 



units would not group themselves together into a circular shape 

 without poor utilization of the space they occupy but it has been 

 found that by properly constructing the individual units and by 

 suitable arrangement of the cable layup, a cross-section is obtained 

 with the groups keystoning together nicely and presenting no notice- 

 able voids. 



The cable core must also have a certain firmness or density to give 



Fig. 7 — Section of 1818 pair 26 A.W.G. cable showing units separated. 



the best support to the sheath and insure satisfactory handling as the 

 cables are being installed. With ribbon paper insulation the ratio of 

 the amount of insulation to the non-copper space in a cable was found 

 to be a fairly good criterion of the firmness required. With the 

 fundamentally different physical characteristics of the pulp insulated 

 wire this relationship was altered and experimental trials were there- 

 fore necessary to determine the approximate size of pulp insulated 



