magnetograph

A device for detecting and recording variations in the intensity and direction of magnetic fields.

A magnetometer arranged to give an automatic and continuous record of the changes in position of the magnet under the influence of the earth. This is accomplished by the reflection of a spot of light from a mirror attached to the magnet on to a drum of sensitized paper turned by clockwork.

The record of a magnetometer; a magnetogram.

An automatic instrument for registering, by photography or otherwise, the states and variations of any of the terrestrial magnetic elements.

A instrument for measuring changes in the direction and intensity of magnetic fields

a scientific instrument that registers magnetic variations (especially variations of the earth’s magnetic field)