the cut-off relay winding
of a regular line so far as test conditions and supervisory relay
operation are concerned. The equipment illustrated in the second office
is that of a _B_-board, it being understood that the called subscriber's
line is multipled through both the _A_- and _B_-boards at that office.
The part of the equipment that is at this point unfamiliar to the reader
is, therefore, the cord circuit at the _B_-operator's board. This
includes, broadly speaking, the means: (1) for furnishing battery
current to the called subscriber; (2) for accomplishing the ringing of
the called subscriber and for automatically stopping the ringing when he
shall respond; (3) for performing the ordinary switching functions in
connection with the relays of the called subscriber's line in just the
same way that an _A_-operator's cord carries out these functions; and
(4) for causing the operation of the calling supervisory relay of the
_A_-operator's cord circuit in just the same manner, under control of
the connected called subscriber, as if that subscriber's line had been
connected directly to the _A_-operator's cord circuit.

[Illustration: Fig. 371. Inter-Office Connection--Western Electric
System]

The operation of these devices in the _B_-operator's cord circuit may
be best understood by following the establishment of the connection.
Assuming that the calling subscriber in the first office desires a
connection with the subscriber's line shown in the second office, and
that the _A_-operator at the first office has answered the call, she
will then communicate by order wire with the _B_-operator at the second
office, stating the number of the called subscriber and receiving from
that operator in return the number of the trunk to be employed. The two
operators will then proceed simultaneously to establish the connection,
the _A_-operator inserting the calling plug into the outgoing trunk
jack, and the _B_-operator inserting the trunk plug into the multiple
jack of the called subscriber's line after testing. We will assume at
first that the called subscriber's line is found idle and that both of
the operators complete their respective portions of the work at the same
time and we will consider first the condition of the calling supervisory
relay at the _A_-operator's position.

The circuit of the calling supervisory lamp will have been closed
through the resistance coil _1_ connected with the outgoing trunk jacks
and the lamp w