A NEW TYPE OF UNDERGROUND TELEPHONE WIRE 451 



ground for binding post cross-connection so as to provide a test point 

 rather than spHcing the bridging wire in permanently and burying the 

 splice in the ground. A small terminal has been provided for this 

 purpose. The buried wires are brought up into the terminal housing 

 through a galvanized iron pipe in order to provide protection of the 

 rubber insulation from sunlight. The terminal is mounted on any 

 convenient pole or post or on a short stub set for the ]uirpose. 



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Fig. 4 — Plo\ving-in two pairs ofburied wire along roadside. 



As buried wire will, in general, be associated with exposed wire 

 circuits, it is planned to provide the same type of electrical protection 

 at subscribers' premises for buried circuits as for drops from open wire 

 or exposed cable circuits. It is also planned to provide protection for 

 buried wire at junctions with open-wire lines over one-half mile in 

 length. 



Plowing-in Operations 



The success of buried wire is in considerable measure dependent 

 upon the efficiency of the equipment provided for plowing it into the 

 ground. This problem has therefore been studied carefully with a 

 view to reducing the traction requirements to a minimum for the 

 desired depth of placing, so as to permit the use of readily available 

 tractive equipment. Experiments have indicated that in a given type 

 of soil the tractive load on the plow increases approximately as the 

 square of the depth of setting. The choice of depth is, of course, a 



