e lower part of the
brass mounting strip _C_ but insulated therefrom. The tip spring of
the jack is bent down as usual to engage the tip of the plug, as
better shown in the lower cut of Fig. 252, and then continues in an
extension _D_, which passes through a hole in the mounting plate _C_.
This tip spring in its normal position rests against another spring as
shown, which latter spring forms one terminal of the drop winding.

The drop or annunciator is of tubular form, and the shutter is so
arranged on the front of the mounting strip _C_ as to fall directly
above the extension _D_ of the tip spring. As a result, when the plug
is inserted into the jack, the upward motion of the tip spring forces
the drop into its restored position, as indicated in the lower cut of
the figure. These drops and jacks are usually mounted in banks of
five, as shown in Fig. 253.

[Illustration: Fig. 253. Strip of Kellogg Drops and Jacks]

Western Electric Type:--The combined drop and jack of the Western
Electric Company recently put on the market to meet the demands of the
independent trade, differs from others principally in that it employs
a spherical drop or target instead of the ordinary flat shutter. This
piece of apparatus is shown in its three possible positions in Fig.
254. The shutter or target normally displays a black surface through a
hole in the mounting plate. The sphere forming the target is out of
balance, and when the latch is withdrawn from it by the action of the
electromagnet it falls into the position shown in the middle cut of
Fig. 254, thus displaying a red instead of a black surface to the view
of the operator. When the operator plugs in, the plug engages the
lower part of an =S=-shaped lever which acts on the pivoted sphere to
restore it to its normal position. A perspective view of one of these
combined line signals and jacks is shown in Fig. 255.

A feature that is made much of in recently designed drops and jacks
for magneto service is that which provides for the ready removal of the
drop coil, from the rest of the structure, for repair. The drop and
jack of the Western Electric Company, just described, embodies this
feature, a single screw being so arranged that its removal will permit
the withdrawal of the coil without disturbing any of the other parts or
connections. The coil windings terminate in two projections on the
front head of the spool, and these register with spring clips on the
inside of the shell s