84 



BELL SYSTEM TECILMCAL JOURNAL 



be systematically arranged and facilities provided for making quick 

 changes in the circuit arrangement. The circuits are wired through 

 jacks installed in groups in test boards for this purpose and to facilitate 

 testing. One of these boards is illustrated in Fig. 28. This particular 

 board is located in one of the larger offices. The test boards in one 

 of the repeater stations, such as Bedford, would consist of a smaller 



Fig. 28 — Test Boards 



number of positions. A position is three feet in length, 

 each position bears a number. 



Stations and Power Plants 



In Fig. 28 



Telephone repeaters of either the two-wire or four-wire type are 

 connected to the circuits at approximate intervals of either 50 or 100 

 miles, depending upon the type of facilities which it is economical 

 to use in the different circuits and the kind of service for which a given 

 circuit is intended. As mentioned above, telegraph repeaters are 

 installed at about 100-mile intervals. At some of these points existing 

 offices are used while in a number of cases it was necessary to erect 

 buildings for the sole purpose of housing the repeaters, testing appa- 

 ratus and other equipment associated with the cable. For example, 

 new buildings of fire-proof construction were erected at Shippensburg, 

 Bedford and Ligonier. Fig. 29 is a view of the building at the latter 

 point and the other two buildings are similar to this one, the dimensions 

 being about 50 by 80 feet. Power plants are installed in these build- 



