o that the proper connections for the coil are
automatically made by the mere insertion of the coil into the shell.

[Illustration: Fig. 254. Western Electric Drop and Jack]

[Illustration: Fig. 255. Western Electric Drop and Jack]

Dean Type:--The combined drop and jack of the Dean Electric Company is
illustrated in Figs. 256 and 257. The two perspective views show the
general features of the drop and jack and the method by which the
magnet coil may be withdrawn from the shell. As will be seen the
magnet is wound on a hollow core which slides over the iron core, the
latter remaining permanently fixed in the shell, even though the coil
be withdrawn.

Fig. 258 shows the structural details of the jack employed in this
combination and it will be seen that the restoring spring for the drop
is not the tip spring itself, but another spring located above and
insulated from it and mechanically connected therewith.

[Illustration: Fig. 256. Dean Drop and Jack]

[Illustration: Fig. 257. Dean Drop and Jack]

[Illustration: Fig. 258. Details of Dean Jack]

Monarch Type:--Still another combined drop and jack is that of the
Monarch Telephone Manufacturing Company of Chicago, shown in sectional
view in Fig. 259. This differs from the usual type in that the
armature is mounted on the front end of the electromagnet, its latch
arm retaining the shutter in its normal position when raised, and
releasing it when depressed by the attraction of the armature. As is
shown, there is within the core of the magnet an adjustable spiral
spring which presses forward against the armature and which spring is
compressed by the attraction of the armature of the magnet. The
night-alarm contact is clearly shown immediately below the strip which
supports the drop, this consisting of a spring adapted to be engaged
by a lug on the shutter and pressed upwardly against a stationary
contact when the shutter falls. The method of restoration of the
shutter in this case is by means of an auxiliary spring bent up so as
to engage the shutter and restore it when the spring is raised by the
insertion of a plug into the jack.

[Illustration: Fig. 259. Monarch Drop and Jack]

_Code Signaling._ On bridging party lines, where the subscribers
sometimes call other subscribers on the same line and sometimes call
the switchboard so as to obtain a connection with another line, it is
not always easy for the operator at the switchboard to distinguish
whether the call