# MAGNETIC CIRCLE

A sphere of specified radius about the magnetic compass location to be kept free of any magnetic or electrical equipment which would interfere with the compass.

## Related Terms

### SAFETY CONTROL

Device to stop unit, equipment or system if unsafe pressure and/or temperatures and/or dangerous conditions are reached.

### ARMATURE DEMAGNETIZATION

The reduction in the effective magnetic lines of force, produced by the armature current.

### RUNNING TIME

Amount of time an unit, equipment or system is run per hour or per 24 hours.

### AIR GAP

The space between magnetic poles, or between the rotating and stationary assemblies in a motor or generator.

### 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.

### HALVING

The process of adjusting magnetic compass correctors so as to remove half of the deviation on the opposite cardinal or adjacent intercardinal headings to those on which adjustment was originally made when all deviation was removed. This is done to equalize the error on opposite headings.

### HALVING

The process of adjusting magnetic compass correctors so as to remove half of the deviation on the opposite cardinal or adjacent intercardinal headings to those on which adjustment was originally made when all deviation was removed. This is done to equalize the error on opposite headings.

### HEELING MAGNET

A permanent magnet placed vertically in a tube under the center of a marine magnetic compass, to correct for heeling error.

### GRID MAGNETIC ANGLE

Angular difference in direction between grid north and magnetic north. It is measured east or west from grid north. Grid magnetic angle is sometimes called GRID VARIATION or GRIVATION.

### GYROCOMPASS

A compass having one or more gyroscopes as the directive element, and which is northseeking. Its operation depends upon four natural phenomena, namely gyroscopic inertia, gyroscopic precession, the earth's rotation, and gravity. When such a compass controls remote indicators, called GYRO REPEATERS, it is called a master gyrocompass.

### Related questions

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