on of drops, once employed by the Western
Telephone Construction Company with considerable success, was to hang
the shutter in such position that it would fall immediately in front
of the jack so that the operator in order to reach the jack with the
plug would have to push the plug directly against the shutter and thus
restore it to its normal or raised position. In this construction the
coil of the drop magnet was mounted directly behind the jack, the
latch rod controlled by the armature reaching forward, parallel with
the jack, to the shutter, which, as stated, was hung in front of the
jack. This resulted in a most compact arrangement so far as the space
utilization on the front of the board was concerned and such combined
drops and jacks were mounted on about 1-inch centers, so that a bank
of one hundred combined drops and jacks occupied a space only a little
over 10 inches square.

A modification of this scheme, as used by the American Electric
Telephone Company, was to mount the drop immediately over the jack so
that its shutter, when down, occupied a position almost in front of,
but above, the jack opening. The plug was provided with a collar,
which, as it entered the jack, engaged a cam on the base of the
shutter and forced the latter mechanically into its raised position.

Neither of these methods of restoring--_i.e._, by direct contact
between the shutter or part of it and the plug or part of it--is now
as widely used as formerly. It has been found that there is no real
need in magneto switchboards for the very great compactness which the
hanging of the shutter directly in front of the drop resulted in, and
the tendency in later years has been to make the combined drops and
jacks more substantial in construction at the expense of some space on
the face of the switchboard.

[Illustration: Fig. 252. Kellogg Drop and Jack]

Kellogg Type:--A very widely used scheme of mechanical restoration is
that employed in the Miller drop and jack manufactured by the Kellogg
Switchboard and Supply Company, the principles of which may be
understood in connection with Fig. 252. In this figure views of one of
these combined drops and jacks in three different positions are shown.
The jack is composed of the framework _B_ and the hollow screw _A_,
the latter forming the sleeve or thimble of the jack and being
externally screw-threaded so as to engage and bind in place the front
end of the framework _B_. The jack is mounted on th