354 THE BELL SYSTEM TECHNICAL JOURNAL, MARCH 1954 



mechanical properties, the metal jacket is corrugated circumferentially. 

 Between the metal layer and the plastic sheathing, a bonding viscous 

 thermoplastic compound is applied (Fig. 2). Normally, this compound 

 fills the depressions of the corrugations on the metal surface adjacent to 

 the surrounding polyethylene jacket. 



The sheathed cable leaves the extruder with an essentially uniform 

 speed, under pulling force of a capstan. For various sizes of cables and 

 production settings, this speed may range from 30 to 80 feet per minute. 

 After leaving the extruder, the cable is cooled in a trough of water and, 

 before reaching the testing position, dried with compressed air. 



Fig. 1 — Polyethylene sheath telephone cable. 



