employed, and the receiver and
transmitter if the breast plate type of transmitter is employed--in a
plug, and a flexible cord connecting the plug terminates with the
apparatus. The portions of the operator's talking circuit that are
located permanently in the switchboard cabinet are in such cases
terminated in a jack, called an operator's _cut-in jack_. This is
usually mounted on the front rail of the switchboard cabinet just
below the key shelf. Such a cut-in jack is shown in Fig. 271 and it is
merely a specialized form of spring jack adapted to receive the short,
stout plug in which the operator's transmitter, or transmitter and
receiver, terminate. By this arrangement the operator is enabled
readily to connect or disconnect her talking apparatus, which is worn
on her person, whenever she comes to the board for work or leaves it
at the end of her work. A complete operator's telephone set, or that
portion that is carried on the person of the operator, together with
the cut-in plug, is shown in Fig. 272.

[Illustration: Fig. 271. Operator's Cut-in Jack]

[Illustration: Fig. 272. Operator's Talking Set]

Circuits of Complete Switchboard. We may now discuss the circuits of
a complete simple magneto switchboard. The one shown in Fig. 273 is
typical. Before going into the details of this, it is well to inform
the student that this general form of circuit representation is one
that is commonly employed in showing the complete circuits of any
switchboard. Ordinarily two subscribers' lines are shown, these
connecting their respective subscribers' stations with two different
line equipments at the central office. The jacks and signals of these
line equipments are turned around so as to face each other, in order
to clearly represent how the connection between them may be made by
means of the cord circuit. The elements of the cord circuit are also
spread out, so that the various parts occupy relative positions which
they do not assume at all in practice. In other words it must be
remembered that, in circuit diagrams, the relative positions of the
parts are sacrificed in order to make clear the circuit connections.
However, this does not mean that it is often not possible to so locate
the pieces of apparatus that they will in a certain way indicate
relative positions, as may be seen in the case of the drop and jack in
Fig. 273, the drop being shown immediately above the jack, which is
the position in which these parts are loc