Connect one bar of the switch to one end of the field coil and the
other bar to one pole of the battery, and connect the other pole
of the battery to the other field coil. To reverse the motor,
simply change the switch.
[Illustration: Reverse for a Small Motor]
Referring to the illustration, the letters indicate as follows:
FF, field of motor; BB, brushes of motor; AA, bars of
pole-changing switch; DD, center points of switch; CC, outside
points of switch.
--Contributed by Leonard E. Parker, Plymouth, Ind.
** To Drive Away Dogs [106]
The dogs in my neighborhood used to come around picking up scraps.
After I connected up my induction coil, as shown in the sketch, we
were not bothered with them. A indicates the ground; B, switch;
and C, a bait of meat, or a tempting bone.
[Illustration: Shocking-Machine]
--Contributed by Geo. W. Fry, 903 Vine St., San Jose, Cal.
** An Automatic Lock [106]
The illustration shows an automatic lock operated by electricity,
one cell being sufficient. When the circuit is broken a weight, A,
attached to the end of the armature B, tends to push the other end
of the armature into the screw eye or hook C, which is in the
door, thus locking the door.
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