magnets. The electricity will be from the centre to the circumference in
one set of discs, and from the circumference to the centre in those on each
side of them; thus the action of the whole will conjoin to produce one
combined and more powerful current.

159. I have rather, however, been desirous of discovering new facts and new
relations dependent on magneto-electric induction, than of exalting the
force of those already obtained; being assured that the latter would find
their full development hereafter.

* * * * *

160. I referred in my former paper to the probable influence of terrestrial
magneto-electric induction (137.) in producing, either altogether or in
part, the phenomena observed by Messrs. Christie and Barlow[A], whilst
revolving ferruginous bodies; and especially those observed by the latter
when rapidly rotating an iron shell, which were by that philosopher
referred to a change in the ordinary disposition of the magnetism of the
ball. I suggested also that the rotation of a copper globe would probably
insulate the effects due to electric currents from those due to mere
derangement of magnetism, and throw light upon the true nature of the
phenomena.

[A] Christie, Phil. Trans. 1825, pp. 58, 347, &c. Barlow, Phil. Trans.
1825, p. 317.

161. Upon considering the law already referred to (114.), it appeared
impossible that a metallic globe could revolve under natural circumstances,
without having electric currents produced within it, circulating round the
revolving globe in a plane at right angles to the plane of revolution,