[Illustration:  Fig. 260.  Code Signal Attachment]

The Monarch Company provides in another way for code signaling at the switchboard.  In some cases there is a special attachment, shown in Fig. 260, by means of which the code signals are repeated on the night-alarm bell.  This is in the nature of a special attachment placed on the drop, which consists of a light, flat spring attached to the armature and forming one side of a local circuit.  The other side of the circuit terminates in a fixture which is mounted on the drop frame and is provided with a screw, having a platinum point forming the other contact point; this allows of considerable adjustment.  At the point where the screw comes in contact with the spring there is a platinum rivet.  When an operator is not always in attendance, this code-signaling attachment has some advantages over the drop as a signal interpreter, in that it permits the code signals to be heard from a distance.  Of course, the addition of spring contacts to the drop armature tends to complicate the structure and perhaps to cut down the sensitiveness of the drop, which are offsetting disadvantages.

[Illustration:  Fig. 261.  Combined Drop and Ringer]

For really long lines, this code signaling by means of the drop is best provided for by employing a combined drop and ringer, although in this case whatever advantages are secured by the mechanical restoration of the shutter upon plugging in are lost.  Such a device as manufactured by the Dean Electric Company is shown in Fig. 261.  In this the ordinary polarized ringer is used, but in addition the tapper rod carries a latch which, when vibrated by the ringing of the bell, releases a shutter and causes it to fall, thus giving a visual as well as an audible signal.

Electrical.  Coming now to the electrical restoration of drop shutters, reference is made to Fig. 262, which shows in side section the electrical restoring drop employed by the Bell companies and manufactured by the Western Electric Company.  In this the coil 1 is a line coil, and it operates on the armature 2 to raise the latch lever 3 in just the same manner as in the ordinary tubular drop.  The latch lever 3 acts, however, to release another armature 4 instead of a shutter.  This armature 4 is pivoted at its lower end at the opposite end of the device from the armature 2 and, by falling outwardly when released, it serves to raise the light shutter 5.  The restoring coil of this device is shown at 6, and when energized it attracts the armature 4 so as to pull it back under the catch of the latch lever 3 and also so as to allow the shutter 5 to fall into its normal position.  The method of closing the restoring circuit is by placing coil 6 in circuit with a local battery and with a pair of contacts in the jack, which latter contacts are normally open but are bridged across by the plug when it enters the jack, thus energizing the restoring coil and restoring the shutter.