[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The two perspective views show the general features of the drop and jack and the method by which the magnet coil may be withdrawn from the shell.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core which slides over the iron core, the latter remaining permanently fixed in the shell, even though the coil be withdrawn.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 is for her or for some other party on the line.  On such lines, of course, code ringing is used and in most cases the operator’s only way of distinguishing between calls for her and those for some sub-station parties on the line is by listening to the rattling noise which the drop armature makes.  In the case of the Monarch drop the adjustable spring tension on the armature is intended to provide for such an adjustment as will permit the armature to give a satisfactory buzz in response to the alternating ringing currents, whether the line be long or short.