. The telephone system of the British post office. A practical handbook . co/v/vecrz/va Figure 76. permanent current, which also deflects the needle to the right. When thepermanent current is stopped by the removal of the receivers, the shutterdrops, and calls the attention of the operator. There are three self-restoring indicators attached to the three circuitsbetween the switch and the National Companys Exchange. These arejoined up as sho vvn in Figure 77. It will be seen that the two lines from the ^osr Office t4^r^of*At. Cos SjtcM^yvas IHOtcJt-rott. OFi FtM Tons FlGUBE Company
. The telephone system of the British post office. A practical handbook . co/v/vecrz/va Figure 76. permanent current, which also deflects the needle to the right. When thepermanent current is stopped by the removal of the receivers, the shutterdrops, and calls the attention of the operator. There are three self-restoring indicators attached to the three circuitsbetween the switch and the National Companys Exchange. These arejoined up as sho vvn in Figure 77. It will be seen that the two lines from the ^osr Office t4^r^of*At. Cos SjtcM^yvas IHOtcJt-rott. OFi FtM Tons FlGUBE Company come to the two outer springs of an eight-point switch-spring, In the normal condition these two lines pass through the back or■line coil of the self-restoring indicator by means of the inner springs(Figure 77). A ring from the Nationtvl causes the shutter to fajl forward 90 Junction Arrangements, thus indicating a call. The insertion of a peg at the Post Office breaks thocontacts of the inner springs, thus cutting out the line coil of the indicatorand at the same time causes the two top springs to come into contactthus closing the circuit of a local battery and restoring the indicator to itsnormal condition. The mode of proceedure is as follows:—Subscriber io5i rings up,dropping the indicator in connection with his line at the National Ex-change. The National operator inserts a peg into his switch-spring, andascertains the nature of the service required by throwing forward thespeaking key. If connection with a local subscriber is desired, t
Size: 2529px × 988px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjecttelepho, bookyear1901
