hen
the tapper began to strike the gongs the tapper would be accelerated
and brought practically into tune with the current frequency, and the
ringing would continue regularly as long as the current flowed. It
will be seen that the under-tuned system was, therefore, one involving
some difficulty in starting in order to provide for proper regularity
while actually ringing.

Ringers of this kind were always made with but a single gong, it being
found difficult to secure uniformity of ringing and uniformity of
adjustment when two gongs were employed. Although no ringers of this
type are being made at present, yet a large number of them are in use
and they will consequently be described. Their action is interesting
in throwing better light on the more improved types, if for no other
reason.

Figs. 178 and 179 show, respectively, side and front views of the
original Kellogg bell. The entire mechanism is self-contained, all
parts being mounted on the base plate _1_. The electromagnet is of the
two-coil type, and is supported on the brackets _2_ and _3_. The
bracket _2_ is of iron so as to afford a magnetic yoke for the field of
the electromagnet, while the bracket _3_ is of brass so as not to
short-circuit the magnetic lines across the air-gap. The reed
tongue--consisting of the steel spring _5_, the soft-iron armature
pieces _6_, the auxiliary spring _7_, and the tapper ball _8_, all of
which are riveted together, as shown in Fig. 178--constitutes the only
moving part of the bell. The steel spring _5_ is rigidly mounted in the
clamping piece _9_ at the upper part of the bracket _3_, and the reed
tongue is permitted to vibrate only by the flexibility of this spring.
The auxiliary spring _7_ is much lighter than the spring _5_ and has
for its purpose the provision of a certain small amount of flexibility
between the tapper ball and the more rigid portion of the armature
formed by the iron strips _6-6_. The front ends of the magnet pole
pieces extend through the bracket _3_ and are there provided with
square soft-iron pole pieces _10_ set at right angles to the magnet
cores so as to form a rather narrow air-gap in which the armature may
vibrate.

[Illustration: Fig. 178. Under-Tuned Ringer]

The cores of the magnet and also the reed tongue are polarized by
means of the =L=-shaped bar magnet _4_, mounted on the iron yoke _2_
at one end in such manner that its other end will lie quite close to
the end of the spring _5_, whi