applied as in fig. 11, a current of electricity through the galvanometer
was produced; but if their place was a little shifted, as in fig. 12, a
current in the contrary direction resulted; the fact being, that in the
first instance the galvanometer indicated the difference between a strong
current through A and a weak one through B, and in the second, of a weak
current through A and a strong one through B (92.), and therefore produced
opposite deflections.

96. So also when the two conductors were equidistant from the magnetic
poles, as in fig. 13, no current at the galvanometer was perceived,
whichever way the disc was rotated, beyond what was momentarily produced by
irregularity of contact; because equal currents in the same direction
tended to pass into both. But when the two conductors were connected with
one wire, and the axis with the other wire, (fig. 14,) then the
galvanometer showed a current according with the direction of rotation
(91.); both conductors now acting consentaneously, and as a single
conductor did before (88.).

97. All these effects could be obtained when only one of the poles of the
magnet was brought near to the plate; they were of the same kind as to
direction, &c., but by no means so powerful.

98. All care was taken to render these results independent of the earth's
magnetism, or of the mutual magnetism of the magnet and galvanometer
needles. The contacts were made in the magnetic equator of the plate, and
at other parts; the plate was placed horizontally, and the poles
vertically; and other precautions were taken. But the absence of any
interference of the kind referred to, was readily shown by the want of all
effect when the disc was removed from the poles, or the poles from the
disc; every other circumstance remaining the same.