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BELL SYSTEM TECHNICAL JOURNAL 



type of construction followed in such areas. With continuous build- 

 ing construction the distributing cables are often attached to the rear 

 walls as in Fig. 12 or extended through the basements of the buildings. 

 Underground cables are carried in conduit consisting of various 

 combinations of multiple tile duct. A typical duct run, shown in 



Fig. 12 — Distribution telephone cable attached to rear wall of building showing 

 terminal boxes and entrance by twisted pair into cellar. 



Fig. 13, illustrates the materials and methods of construction generally 

 employed. 



At the central office the conduit system is designed to meet the 

 ultimate requirements of the building and terminates in a cable vault 

 as shown in Fig. 14. With this entrance arrangement the main 



