The field of force established by a magnet pole. The attractions and
repulsions exercised by such a field follow the course of the electro-
magnetic lines of force. (See also Field of Force.) Thus the tendency of
a polarized needle attracted or repelled is to follow, always keeping
tangential to curved lines, the direction of the lines of force, however
sweeping they may be. The direction of magnetic lines of force is
assumed to be the direction in which a positive pole is repelled or a
negative one attracted; in other words, from the north pole of a magnet
to its south pole in the outer circuit. The direction of lines of force
at any point, and the intensity or strength of the field at that point,
express the conditions there. The intensity may bc expressed in terms of
that which a unit pole at unit distance would produce. This intensity as
unitary it has been proposed to term a Gauss. (See Weber.)

The direction of the lines of force in a magnetic field are shown by the
time-honored experiment of sprinkling filings of iron upon a sheet of
paper held over a magnet pole or poles. They arrange themselves, if the
paper is tapped, in more or less curved lines tending to reach from one
pole of the magnet to the other. Many figures may be produced by
different conditions. Two near poles of like name produce lines of force
which repel each other. (See Magnetic Curves.)

A magnetic and an electro-magnetic field are identical in all essential
respects; the magnetic field may be regarded as a special form of the
electro-magnetic field, but only special as regards its production and
its defined north and south polar regions.

Synonyms–Magnetic Spin (not much used).