MANUFACTURING LEAD-COVERED TELEPHONE CABLE 323 



through the stranding machine as many times as there were layers in 

 the finished core. 



The old process of pulling cable core into lead pipe is illustrated in 

 Fig. 4. This picture was posed a few years ago, and the man standing 

 in the foreground was one of a gang who formerly did this work. 



Fig. 3 — Old stranding department about 1890 



A forward step in design of insulating equipment was made with the 

 use of pads concentric with the wire which permitted very much higher 

 insulating speeds and very much reduced paper breakage. The twist- 

 ing machines were also modified to reduce uneven twisting and permit 

 greater speed. 



Another step was the development of multiple drum stranders 

 permitting a number of layers or complete small cables to be made in 

 one operation. Also, extrusion presses were improved so that a con- 

 tinuous sheath of lead alloy could be extruded directly on to the cable 

 core, eliminating the puUing-in operation. 



During the period from about 1900 to 1920 many changes were 

 made to increase output and improve the quality. Improvements in 

 machines made possible the use of thinner and narrower insulating 

 papers so that a greater number of pairs of wires could be placed within 

 the same cross-sectional area, tending greatly to decrease the cost per 

 circuit. Cables made about 1888 contained 50 pairs of 18-gauge con- 

 ductor. By about 1902 improvements had been made which per- 

 mitted 606 pairs of 22-gauge wire to be put into a sheath of 2^ in. 



