MACHINE SWITCHING TELEPHONE SYSTEM 



67 



and the fixed terminals or multiple, to which the movable member 

 can make connection, corresponds to the jacks of the manual system. 

 Fig. 10 shows the fixed terminals or multiple to which the selectors 

 connect. This multiple consists of flat punchings about Z l A feet 

 long and 1 inch wide overall. Each of these strips has lugs on each 

 side with which the selectors can make contact. In this particular 

 panel, three hunderd of these strips are piled one above the other, 

 separated by insulation, and securely bolted together, forming a panel 

 about 15 inches high. This panel provides a multiple consisting of 

 "tip," "ring" and "sleeve" connection for one hundred lines appear- 

 ing sixty times; that is, thirty on each side. The insulating material 

 consists of special impregnated paper and is of such a nature that, 



J, . . J, . . J, , ■ .1, y A . . A , . ■>! i . i, i. ■'. y i"i y ■*! y A y Ay Ay l ' i 1 , 1 A I f ■** I f A If A yAiyg 



Fig. 10 — Selector Multiple Bank 



after the panel is assembled and baked, it becomes inert and is not 

 adversely affected by any conditions met with in a central office. 

 It is this panel which has given the name to the system. 



The selector (see Figs. 9 and 13) consists of a metal tube supported 

 in bearings allowing vertical motion and carrying five sets of brushes. 

 Each one of the five sets of brushes is arranged to make connections 

 to the tip, ring and sleeve terminals of the panel banks before which 

 it normally stands, and the tip, ring and sleeve contact members of 

 all five of these brushes are multipled together. They are normally 

 free from contact with the terminals, but any set may be tripped me- 



