east over to west, the marked pole wont eastward (or towards
the ball); when the rotation was in the opposite direction, the marked pole
went westward.

165. By twisting the silk of the needles, the latter were brought into a
position perpendicular to the plane of the magnetic meridian; the ball was
again revolved, with its axis parallel to the needles; the upper was
affected as before, and the deflection was such as to show that both here
and in the former case the needle was influenced solely by currents of
electricity existing in the brass globe.

166. If the upper part of the revolving ball be considered as a wire moving
from east to west, over the unmarked pole of the earth, the current of
electricity in it should be from north to south (99. 114. 150.); if the
under part be considered as a similar wire, moving from west to east over
the same pole, the electric current should be from south to north; and the
circulation of electricity should therefore be from north above to south,
and below back to north, in a metal ball revolving from east above to west
in these latitudes. Now these currents are exactly those required to give
the directions of the needle in the experiments just described; so that the
coincidence of the theory from which the experiments were deduced with the
experiments themselves, is perfect.

167. Upon inclining the axis of rotation considerably, the revolving ball
was still found to affect the magnetic needle; and it was not until the
angle which it formed with the magnetic dip was rendered small, that its
effects, even upon this apparatus, were lost (153.). When revolving with
its axis parallel to the dip, it is evident that the globe becomes
analogous to the copper plate; electricity of one kind might be collected
at its equator, and of the other kind at its poles.

168. A current in the ball, such as that described above (161.), although
it ought to deflect a needle the same way whether it be to the right or the
left of the ball and of the axis of rotation, ought to deflect it the
contrary way when above or below the ball; for then the needle is, or ought
to be, acted upon in a contrary direction by the current. This expectation
was fulfilled by revolving the ball beneath the magnetic needle, the latter
being still inclosed in its jar. When the ball was revolved from east over
to west, the marked pole of the needle, instead of passing eastward, went
westward; and when revolved from west over