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BELL SYSTEM TECHNICAL JOURNAL 



range is sufficient. Jacks and other testing conveniences have been 

 omitted to save bulk and cost. 



Fig. 7 — Transmission testboard for maintaining long distance circuits. 



The new instruments for the local plant are not limited to local 

 testing but also have extensive application in the toll plant especially 

 in the smaller offices which do not have many toll circuits. Because 



