The successive rows of polarized molecules assumed to exist in
magnetized iron. Each molecule represents an infinitely small magnet,
and its north pole points to the south pole of the next molecule. Such a
string or row is a theoretical conception based on the idea that the
molecules in a magnet are all swung in to parallelism in the magnetizing
process. A magnetic filament may be termed the longitudinal element of a
magnet. (See Magnetism, Hughes’ Theory of.)

[Transcriber's note: This description parallels the modern
notion of electron spin as the basis of magnetism in materials.]