A small, slender, magnetized bar which tends to align itself with magnetic lines of force.



Related Terms

FLINDERS BAR

A bar of soft unmagnetized iron placed vertically near a magnetic compass to counteract deviation caused by magnetic induction in vertical soft iron of the craft

DECLINATION VARIOMETER

An instrument that measures changes in the declination of the earth's magnetic field, consisting of a permanent bar magnet, usually about 0.4 inch (1 centimeter) long, suspended with a plane mirror from a fine quartz fiber 26 inches (515 centimeters) in length; a lens focuses to a point a beam of light reflected from the mirror to recording paper mounted on a rotating drum. Also known as D variometer.

SENSIBILITY

The ability of a magnetic compass card to align itself with the magnetic meridian after deflection.

AZIMUTH BAR

An instrument for measuring azimuths, particularly a device consisting of a slender bar with a vane at each end, and designed to fit over a central pivot in the glass cover of a magnetic compass.

LUNAR INEQUALITY

  1. Variation in the moon’s motion in its orbit, due to attraction by other bodies of the solar system. 2. A minute fluctuation of a magnetic needle from its mean position, caused by the moon.

BEARING BAR

An instrument for measuring bearings, particularly a device consisting of a slender bar with a vane at each end, and designed to fit over a central pivot in the glass cover of a magnetic compass. See also AZIMUTH BAR.

VIBRATING NEEDLE

A magnetic needle used in compass adjustment to find the relative intensity of the horizontal components of the earth’s magnetic field and the magnetic field at the compass location. Also called HORIZONTAL FORCE INSTRUMENT.

DEFLECTION MAGNETOMETER

A magnetometer in which magnetic fields are determined from the angular deflection of a small bar magnet that is pivoted so that it is free to move in a horizontal plane.

CROSSED-FIELD DEVICE

Any instrument crossed-needle meter which uses the motion of electrons in perpendicular electric and magnetic fields to generate microwave radiation, either as an amplifier or oscillator.

NORTH GEOMAGNETIC POLE

The geomagnetic pole in the Northern Hemisphere. This term should not be confused with NORTH MAGNETIC POLE.

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