TELEPHONE EQUIPMENT FOR LONG CABLE CIRCUITS 139 



material not requiring adjustment when in operation is mounted on 

 the rear, since by this means the rear aisles can be made narrower 

 than the front aisles. Thus, all available space is utilized to the 

 extent that the floor area required per equipment unit in a cable 

 installation will be as small as the maintenance, manufacturing and 

 installing requirements for the apparatus will permit. 



In view of the many different types of equipment units having a 

 variety of special functions which are required to make up a com- 

 plete cable installation, a high degree of uniformity in design is neces- 

 sary to permit efficiency in their use. It is expected that this will be 

 accomplished effectively by applying the panel assembly method 

 in a uniform manner to practically all types of equipment units. All 

 panels are to be of a uniform length, designed to mount on vertical 

 supports spaced 19^" inches between centers. The height of the 

 different panels will vary, according to the amount of apparatus in 

 each unit, but this vertical dimension is in all cases to be a whole 

 multiple of P 4 inches. By applying these specifications widely, it 

 will be possible to secure interchangeability between panels and to 

 employ uniform methods in grouping the different units, thus facili 

 tating their installation and use. 



The simplicity of the design of the equipment units comprising 

 the various panels is also of great importance. This has necessitated 

 careful attention to the forms of the individual pieces of apparatus, 

 in order that these might fulfill their specific functions efficiently 

 while at the same time fitting in well with the general equipment 

 arrangements. To this end, new types of apparatus, such as repeating 

 coils, retardation coils, etc., are being developed especially for cable 

 use. Much will also be accomplished toward the simplification of 

 the panels by carefully avoiding duplication in the accessories to the 

 different types of equipment and by dissociating from the individual 

 units of all types any pieces of apparatus capable of being made com- 

 mon to a number of units, or subject to different methods of applica- 

 tion in different types of offices. 



Other important advantages are anticipated in the panel assembly 

 method. One of these is that it will permit the assembling together 

 on one panel of all of the pieces of apparatus of different types which 

 may be desired to form a distinct equipment unit. In large installa- 

 tions, completely equipped racks including a number of equipment 

 units with the associated testing apparatus may be assembled in the 

 factory on the supporting uprights and wired to the terminals at 

 the top of the rack, thus simplifying the installation work. The loca- 

 tion of the testing apparatus on the same rack with the equipment 



