. The telephone system of the British post office. A practical handbook . all wires on to indicators. At the PostOffice this switch consists of six holes upon the test board. The centralpair of holes are connected to the call wire, the top and bottom pairs 102 Call Wire Key. being connected to the record table or to the battery and indicator bymeans of U links. The up call wire terminates in one indicator, butthere are three switch-springs in connection with it, so that any one ofthe operators may talce calls from the Company. At the Companys endthe wire in connection with the Post Office call
. The telephone system of the British post office. A practical handbook . all wires on to indicators. At the PostOffice this switch consists of six holes upon the test board. The centralpair of holes are connected to the call wire, the top and bottom pairs 102 Call Wire Key. being connected to the record table or to the battery and indicator bymeans of U links. The up call wire terminates in one indicator, butthere are three switch-springs in connection with it, so that any one ofthe operators may talce calls from the Company. At the Companys endthe wire in connection with the Post Office call keys is switched throughto a switch-spring and indicator with a battery in circuit. The call key consists of seven springs (Figure 87), which, when the key isdepressed, are pushed outwards, thus connecting the two long springs tothe two short ones, and so joining the call wire to the operators speakingset. The central springs come in contact, and thus complete the primarycircuit of the speaking set. The mechanical connections of the key areshown in Figure 88. rfT<^. Figure 8g. The record table tablet is joined up as shown in Figure 89. Itwill be seen that there is only one induction coil for each circuit,and that the reversal of the operators pegs brings in a new only one operators set is in circuit both call wires are thrown on tothat operators set. The switch telephone connector is placed in thecentre of the table and is covered by a small door which is cut to permitthe cords to pass through it. These tables accommodate two operators,but this is only necessary in larger exchanges. In certain offices it was found expedient to fit record tables in exchangeswhere there were only two B sections. It must always be remembered indealing with telephone problems that absolute rigidity of practice is notalways desirable, as in this instance. The Telephone i>ysieni ut Post Office. 103 CHAPTER XVTI. The Switch Section. At all the larger offices switch secti
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Keywords: ., bookcentury1900, bookdecade1900, booksubjecttelepho, bookyear1901
