re, as soon as the
bridge cut-off relay operates, the trip magnet becomes inoperative and
can cause no further action of the line switch because its circuit is
broken between the springs _21_ and _22_.

The private or guarding feature is taken care of by the action of the
plunger in closing contacts _19_ and _20_, since the private wire
leading to the bridge cut-off relay is, as has already been stated,
connected to ground when these contacts are closed. This private wire
leads off and is multipled to the private contacts on all the connectors
that have the ability to reach this line, and the fact that this wire
is grounded by the line switch as soon as it becomes busy, establishes
such conditions at all of the connectors that they will refuse to
connect with this line as long as it is busy, in a way that will be
pointed out later on.

_Relation of Line Switch and Connectors._ The vertical and rotary wires
of the subscriber's line are shown leading off to the connector banks at
the left-hand side of Fig. 389, and one side of this connection passes
through the contacts _24_ and _25_ of the bridge cut-off relay on the
line switch. It is through this path that a connection from some other
line through a connector to this line is established and it is seen that
this path is held open until the bridge cut-off relay of the line switch
is operated. For such a connection to this line the bridge cut-off relay
of the line switch is operated over the private wire leading from the
connector, and the operation of the bridge cut-off relay at this time
serves to render inoperative the line switch, so that it will not
perform its usual functions should the called subscriber start to make a
call after his line had been seized.

_Summary of Line-Switch Operation._ To summarize the operation of a line
switch when a call is originated on its line, the first movement of the
calling subscriber's dial will ground the rotary side of the line and
operate the trip magnet. This will cause the plunger to be inserted into
the bank, and thus extend the line to the first selector trunk through
the closing of the right-hand set of springs shown in the lower
right-hand corner of Fig. 389. The insertion of the plunger will also
connect the battery through the left-hand winding of the master-switch
relay and, by the sequence of operations which follows, cause the master
bar to move all of the idle plungers so as to again point them to an
idle trunk. T