e
listening key in each case is the one in the rear and is alike for all
of the cord pairs. The right-hand five ringing keys are so arranged
that pressing the lever to the rear will ring on the answering cord,
while pressing it toward the front will cause ringing current to flow
on the calling plug. In the left-hand five pairs of cords shown in
this cut, the pressure of any one of the keys causes a ringing current
of a certain frequency to flow on the calling cord, this frequency
depending upon which one of the keys is pressed.

[Illustration: Fig. 298. Cord Weight]

An excellent idea of the grouping of the various pieces of apparatus
in a complete simple magneto switchboard may be had from Fig. 297.
While the arrangement here shown is applicable particularly to the
apparatus of the Dean Electric Company, the structure indicated is
none-the-less generally instructive, since it represents good practice
in this respect. In this drawing the stationary plug shelf with the
plug seat is clearly shown and also the hinged key shelf. The hinge of
the key shelf is an important feature and is universally found in all
switchboards of this general type. The key shelf may be raised and
thus expose all of the wiring leading to the keys, as well as the
various contacts of the keys themselves, to inspection.

[Illustration: Fig. 299. Magneto Switchboard, Target Signals]

As will be seen, the switchboard cords leading from the plugs extend
down to a point near the bottom of the cabinet where they pass through
pulley weights and then up to a stationary cord rack. On this cord
rack are provided terminals for the various conductors in the cord,
and it is at this point that the cord conductors join the other wires
leading to the other portions of the apparatus as required. A good
form of cord weight is shown in Fig. 298; and obviously the function
of these weights is to keep the cords taut at all times and to prevent
their tangling.

[Illustration: Fig. 300. Rear View of Target Signal, Magneto
Switchboard]

The drawing, Fig. 297, also gives a good idea of the method of
mounting the hand generator that is ordinarily employed with such
magneto switchboards. The shaft of the generator is merely continued
out to the front of the key shelf where the usual crank is provided,
by means of which the operator is able to generate the necessary
ringing current. Beside the hand generator at each operator's
position, it is quite common in magneto