individual to the subscriber's line are termed the _line equipment;_
this, in the case of a magneto switchboard, consists of the line drop
and the jack together with the associated wiring necessary to connect
them properly in the line circuit. The parts of the switchboard that
are associated with a connecting link--consisting of a pair of plugs
and associated cords with their ringing and listening keys and
clearing-out drop--are referred to as a _cord equipment_. The circuit
of a complete pair of cords and plugs with their associated apparatus
is called a _cord circuit_. In order that there may be a number of
simultaneous connections between different pairs of lines terminating
in a switchboard, a number of cord circuits are provided, this number
depending on the amount of traffic at the busiest time of the day.

_Operator's Equipment._ A part of the equipment that is not individual
to the lines or to the cord circuits, but which may, as occasion
requires, be associated with any of them is called the _operator's
equipment_. This consists of the operator's transmitter and receiver,
induction coil, and battery connections together with the wiring and
other associated parts necessary to co-ordinate them with the rest of
the apparatus. Still another part of the equipment that is not
individual to the lines nor to the cord circuits is the
calling-current generator. This may be common to the entire office or
a separate one may be provided for each operator's position.

Operation in Detail. With these general statements in mind we may
take up in some detail the various operations of a telephone system
wherein the lines center in a magneto switchboard. This may best be
done by considering the circuits involved, without special regard to
the details of the apparatus.

The series of figures showing the cycle of operations of the magneto
switchboard about to be discussed are typical of this type of
switchboard almost regardless of make. The apparatus is in each case
represented symbolically, the representations indicating type rather
than any particular kind of apparatus within the general class to
which it belongs.

_Normal Condition of Line._ In Fig. 240 is shown the circuit of an
ordinary magneto line. The subscriber's sub-station apparatus, shown
at the left, consists of the ordinary bridging telephone but might
with equal propriety be indicated as a series telephone. The
subscriber's station is shown connected with the c