current in the approaching wire is the same
with that of the current in the parts or sides of the spirals nearest to
it, and in the receding wire the reverse of that in the parts nearest to
it.

118. All these results show that the power of inducing electric currents is
circumferentially exerted by a magnetic resultant or axis of power, just as
circumferential magnetism is dependent upon and is exhibited by an electric
current.

119. The experiments described combine to prove that when a piece of metal
(and the same may be true of all conducting matter (213.) ) is passed
either before a single pole, or between the opposite poles of a magnet, or
near electro-magnetic poles, whether ferruginous or not, electrical
currents are produced across the metal transverse to the direction of
motion; and which therefore, in Arago's experiments, will approximate
towards the direction of radii. If a single wire be moved like the spoke of
a wheel near a magnetic pole, a current of electricity is determined
through it from one end towards the other. If a wheel be imagined,
constructed of a great number of these radii, and this revolved near the
pole, in the manner of the copper disc (85.), each radius will have a
current produced in it as it passes by the pole. If the radii be supposed
to be in contact laterally, a copper disc results, in which the directions
of the currents will be generally the same, being modified only by the
coaction which can take place between the particles, now that they are in
metallic contact.

120. Now that the existence of these currents is known, Arago's phenomena
may be accounted for without considering them as due to the formation in
the copper, of a pole of the opposite kind to that approximated, surrounded
by a diffuse polarity of the same kind (82.); neither is it essential that
the plate should acquire and lose its state in a finite time; nor on the
other hand does it seem necessary that any repulsive force should be
admitted as the cause of the rotation (82.).

121. The effect is precisely of the same kind as the electromagnetic
rotations which I had the good fortune to discover some years ago[A].
According to the experiments then made which have since been abundantly
confirmed, if a wire (PN fig. 26.) be connected with the positive and
negative ends of a voltaic buttery, so that the positive electricity shall
pass from P to N, and a marked magnetic pole N be placed near the wire
between it and th