Fig 1 shows several polar directions of the molecules as indicated
by the arrows. Poisson assumed as a necessity of his theory, that
a molecule is spherical; but Dr. Joule's experimental proof of the
elongation of iron by one seven-hundred and-twenty-thousandth of its
length when magnetized, proves at least that its form is not spherical;
and, as I am unable at present to demonstrate my own views as to its
exact form, I have simply indicated its polar direction by arrows--the
dotted oval lines merely indicating its limits of free elastic rotation.

In Fig. 1, at A, we have neutrality by the mutual attraction of each
pair of molecules, being the shortest path in which they could satisfy
their mutual attractions. At B we have the case of superposed magnetism
of equal external value, rendering the wire or rod apparently neutral,
although a lower series of molecules are rotated in the opposite
direction to the upper series, giving to the rod opposite and equal
polarities. At C we have the molecules arranged in a circular chain
around the axis of a wire or rod through which an electric current
has passed. At D we have the evident polarity induced by the earth's
directive influence when a soft iron rod is held in the magnetic
meridian. At E we have a longitudinal neutrality produced in the same
rod when placed magnetic west, the polarity in the latter case being
transversal.

In all these cases we have a perfectly symmetrical arrangement, and I
have not yet found a single case in well-annealed soft iron in which I
could detect a heterogeneous arrangement, as supposed by Ampere, De la
Rive, Weber, Wiedermann, and Maxwell.

We can only study neutrality with perfectly soft Swedish iron. Hard