The phenomena associated with magnetic fields and their effects upon magnetic materials, notably iron and steel. The magnetism of the north-seeking end of a freely suspended magnet is called red magnetism; the magnetism of the south-seeking end is called blue magnetism. Magnetism acquired by a piece of magnetic material while it is in a magnetic field is called induced magnetism. Permanent magnetism is retained for long periods without appreciable reduction, unless the magnet is subjected to a demagnetizing force. The magnetism in the intermediate iron of a ship which tends to change as the result of vibration, aging, or cruising in the same direction for a long period but does not alter immediately so as to be properly termed induced magnetism is called sub permanent magnetism. Magnetism which remains after removal of the magne- tizing force may be called residual magnetism. The magnetism of the earth is called terrestrial magnetism or geomagnetism.

Related Terms

BUMPKIN

The spar projecting from stern of ship

ABRASION RESISTANCE

The ability of a material to resist surface wear.

DIELECTRIC STRENGTH

A measure of the ability of an insulating material to withstand electric stress (voltage) without failure. Fluids with high dielectric strength (usually expressed in volts or kilovolts) are good electrical insulators. (ASTM Designation D 877.)

TRAMP FREIGHTER

A cargo ship engaged in the tramp trade.

CORDAGE

Ropes in the rigging of a ship

WEATHER SIDE

The side of a ship exposed to the wind.

ABSORPTION

The assimilation of one material into another; in petroleum refining, the use of an absorptive liquid to selectively remove components from a process stream.

CARBON RESIDUE

Coked material remaining after an oil has been exposed to high temperatures under controlled conditions.

CONTAMINATION CONTROL

A broad subject which applies to all types of material systems (including both biological and engineering). It is concerned with planning, organizing, managing, and implementing all activities required to determine, achieve and maintain a specified contamination level.

GYRO ERROR

The error in the reading of the gyrocompass, expressed in degrees east or west to indicate the direction in which the axis of the compass is offset from true north.

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