each other, so that the north pole of one approaches the north
pole of the other, there is a sensible attempt for them to push away
from each other. If, however, one of them is turned, so that the north
pole of one is opposite the south pole of the other, they will draw
together.

In this we have the foundation physical action of the dynamo and the
motor. When power is applied to an armature, and it moves through a
magnetic field, the action is just the same as in the case of the hand
drawing the north and the south pole of the two approaching magnets from
each other.

The influence of the electrical disturbance produced by that act
permeated the entire winding of the field and armature, and extended out
on the whole line with which the dynamo was connected. In this way a
current was established and transmitted, and with proper wires was sent
in the form of circuits and distributed so as to do work.

But an electric current, without suitable mechanism, is of no value. It
must have mechanism to use it, as well as to make it. In the case of
light, we have explained how the arc and the incandescent lamps utilize
it for that purpose.

But now, attempting to get something from it in the way of power, means
another piece of mechanism. This is done by the motor, and this motor is
simply a converter, or a device for reversing the action of the
electricity.

Attention is called to Figs. 120 and 121. Let us assume that the field
magnets A, A are the positives, and the magnets B, B the negatives. The
revolving armature has also four magnet coils, two of them, C, C, being
positive, and the other two, D, D, negative, each of these magnet coils
being so connected up that they will reverse the polarities of the
magnets.

[Illustration: _Figs. 120-121._ ACTION OF MAGNETS IN A DYNAMO]

Now in the particular position of the revolving armature, in Fig. 120,
the magnets of the armature have just passed the respective poles of the
field magnets, and the belt E is compelled to turn the armature past the
pole pieces by force in the direction of the arrow F. After the armature
magnets have gone to the positions in Fig. 121, the positives A try to
draw back the negatives D of the armature, and at the same time the
negatives B repel the negatives D, because they are of the same
polarities.

This repulsion of the negatives A, B continues until the armature poles
C, D have slightly passed them, when the polarities of the magnets C, D
ar