. American telephone practice . FIG. METALLIC PARTY-LINE CIRCUIT. ing is concerned, but even half that number would give intolerabletalking service. Another objection to the series party line is that even where me-tallic circuits are used it is practically impossible to properly balancethe line with regard to inductive disturbances. If all the instru-ments are placed in one side of the line, using the other side merelyas a return, the line will be badly unbalanced on account of oneof its sides possessing great impedance, while the other has onlv 426 AMERICAN TELEPHONE PRACTICE. t
. American telephone practice . FIG. METALLIC PARTY-LINE CIRCUIT. ing is concerned, but even half that number would give intolerabletalking service. Another objection to the series party line is that even where me-tallic circuits are used it is practically impossible to properly balancethe line with regard to inductive disturbances. If all the instru-ments are placed in one side of the line, using the other side merelyas a return, the line will be badly unbalanced on account of oneof its sides possessing great impedance, while the other has onlv 426 AMERICAN TELEPHONE PRACTICE. that of the line wire. This may be partially remedied by alternatelyplacing the instruments on one side of the line or the other, as isshown in Fig. 320, but often where this precaution is taken a per-fectly quiet line cannot be secured where the conditions are at alladverse. As a matter of fact, the series party line has no place in moderntelephone practice, it having been almost universally superseded by. FIG. 323.—CARTY BRIDGING BELL PARTY-LIXE SYSTEM. the bridging or multiple system of party line working, as disclosedin the now famous Carty patent.* In Fig. 321 is shown the method of connecting four instrumentsin accordance with the bridging system on a grounded line, andin Fig. 322 four instruments are similarly shown connected on ametallic circuit. It will be seen that the line wire in Fig. 321 or theline wires in Fig. 322 are continuous through all the stations, eachinstrument being placed in a separate bridge wire either betweenthe line wire and ground or between the two line wires. * U. S. patent to John J. Carty, No. 449,106. PARTY LINE SYSTEMS. 427 The circuits of bridging instruments have already been discussedin Chapter IX. The line connections of an n-station metallic cir-cuit bridged line is shown in Fig. 323, this being a copy of the mainfigure in the Carty patent referred to. The various instruments, 2,3, 4, 5, etc., are connected across the two sides, / and l
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