lay will, therefore, stay up due to the
energizing of this locking coil. Another contact operated by the relay
closes the circuit of a low-wound clearing-out drop placed across the
line, thus bridging it across the line. The condition of high impedance
is maintained across the cord circuit normally while the subscribers
are talking; but when either of them rings off, the high-wound relay
pulls up and locks, thus completing the circuit of the clearing-out
drop across the cords. The subsequent impulses sent from the
subscribers' generators operate this drop. The relay is restored or
unlocked and the clearing-out drop disconnected from the cord circuit
by means of a key which opens the locking circuit of the relay. This
key is really a part of the listening key and serves to open this
locking circuit whenever the listening key is operated. The
clearing-out drop is also automatically restored by the action of the
listening key, this connection being mechanical rather than electrical.

Recall Lamp:--The Monarch Company sometimes furnishes what it terms a
recall lamp in connection with the clearing-out drops on its magneto
switchboards. The circuit arrangement is shown in Fig. 290, wherein
the drop is the regular double-wound clearing-out drop like that of
Fig. 284. The armature carries a contact spring adapted to close the
local circuit of a lamp whenever it is attracted. The object of this
is to give the subscriber, whose line still remains connected by a
cord circuit, opportunity to recall the central office if the operator
has not restored the clearing-out drop.

[Illustration: Fig. 290. Cord Circuit with Recall Lamp]

_Lamp-Signal Type._ There has been a tendency on the part of some
manufacturing companies to advocate, instead of drop signals,
incandescent lamp signals for the cord circuits, and sometimes for the
line circuits on magneto boards. In most cases this may be looked upon
as a "frill." Where line lamps instead of drops have been used on
magneto switchboards, it has been the practice to employ, instead of a
drop, a locking relay associated with each lamp, which was so arranged
that when the relay was energized by the magneto current from the
subscriber's station, it would pull up and lock, thus closing the lamp
circuit.

The local circuit, or locking circuit, which included the lamp was
carried through a pair of contacts in the corresponding jacks so
arranged that when the plug was inserted in answer to the