Only approximate insulation of magnetism is possible. There is no perfect insulator. The best ones are only 10,000 times less permeable than iron. Hence lines of force find their way through air and all other substance, being simply crowded together more in paths of iron or other paramagnetic substance.

A sensible time is required to magnetize iron, or for it to part with its magnetism, however soft it may be. This is due to its magnetic inertia and is termed the lag. Permanent or residual magnetism is a phase of it. It is analogous to self-induction of an electric circuit, or to the residual [...]

An approximate cylinder or frustrum of a cone whose sides are formed of lines of magnetic induction. (See Magnetic Induction, Lines of.) The term tube is very curiously applied in this case, because the element or portion of a magnetic field thus designated is in no sense hollow or tubular.

Magnetic induction produced by a stationary field acting upon a stationary body.

The induction produced by a magnetic field which moves with respect to a body, or where the body if moving moves at a different rate, or where the body moves and the field is stationary. In the case where both move, part of the induction may be dynamic and part static. (See Magnetic Induction, Static.)

The apparent permeability of a paramagnetic body as affected by the presence of Foucault currents in the material itself. These currents act exactly as do the currents in the coils surrounding the cores of electro-magnets. They produce lines of force which may exhaust the permeability of the iron, or may, if in an opposite direction, [...]

The force of magnetization within an induced magnet. It is in part due to the action of the surrounding particles of polarized material; in part to the magnetic field. (See Magnetic Induction, Coefficient of.) In a more general way it is the action of a magnet upon bodies in its field of force. In some [...]

The inclination from the horizontal of a magnetic needle placed in the magnetic meridian. (See Magnetic Element–Inclination Map.) Synonym–Magnetic Dip.

Friction gear in which electro-magnetic adherence is employed to draw the wheels together. (See Adherence, Electro-magnetic–Electro-magnetic Friction Gear.)

The damping effect produced on the movements of a mass of metal by proximity to a magnet; the phenomenon illustrated in Arago’s wheel, q. v. When a mass of metal moves in the vicinity of a magnet it cuts the lines of force emanating from its poles, thereby producing currents in its mass; as the [...]