Machine, Toeppler-Holtz.
A modification of the Holtz machine. The priming charge of the armatures
is produced by friction of metallic brushes against metallic buttons on
the face of the rotating plate. (See Machine, Holtz.)
Machine, Wimshurst.
A form of static influence machine. It consists of two plates of glass,
on which radial sectors of tinfoil are pasted. Both plates are rotated
in opposite directions. The sectors of the two plates react one upon the
other, and electric charges of opposite sign accumulate on the opposite
sides of the plates and are collected therefrom by collecting combs.
Mack.
A name, derived from Maxwell, and suggested for the unit of inductance.
It is due to Oliver Heaviside, but has never been adopted. (See Henry.)
Magne-Crystallic Action.
The action of a supposed force of the same name, proposed by Faraday. It
relates to the different action of a magnetic field upon crystalline
bodies, according to the position of their axes of crystallization. A
needle of tourmaline, normally paramagnetic, if poised with its axis
horizontal, is diamagnetic. Bismuth illustrates the same phenomenon. The
subject is obscure. Faraday thought that he saw in it the action of a
specific force.
Magnet.
A body which tends when suspended by its centre of gravity to lay itself
in a definite direction, and to place a definite line within it, its
magnetic axis, q. v., in a definite direction, which, roughly speaking,
lies north and south. The same bodies have the power of attracting iron
(Daniell), also nickel and cobalt.
Magnets are substances which possess the power of attracting iron.
(Ganot.)
[Transcriber's note: Edward Purcell and others have explained magnetic
and electromagnetic phenomenon as relativistic effects related to
electrostatic attraction. Magnetism is caused by Lorentz contraction of
space along the direction of a current. Electromagnetic waves are caused
by charge acceleration and the resulting disturbance of the
electrostatic field. (Electricity and Magnetism: Berkeley Physics
Course Volume 2, 1960)]
Magnet, Anomalous.
A magnet possessing more than the normal number (two) of poles. If two
straight magnets are placed end to end with their south poles in
juxtaposition the compound bar will seem to possess three poles, one at
each end and one in the middle. The apparent pole in the middle is
really made up of two consequent poles, q. v. It sometimes happens that
when a single long thin bar is magnetized consequent poles are produced,
although such magnet is in one piece. This may be accidental, as in such
case it is quite hard to avoid anomalous poles, or, as in the field
magnets of some forms of dynamos, anomalous poles may be purposely
produced.
Magnet, Artificial.
A magnet formed artificially by any method of magnetization (see
Magnetism) applicable to permanent magnets, electro-magnets and
solenoids. It expresses the distinction from the natural magnets or
lodestone, q. v. It is made of steel in practice magnetized by some of
the methods described under Magnetization.