Maker's Name: 
Where made: 
30 × 16 × 49.5 cm

The double metal hook holds in suspension either a compass needle or a magnet.

The suspension filament resists the turning torque, when the suspended magnet tries to align with a local magnetic field.

The angle of twist gives a measure of the strength of the magnetic field.

A more sensitive measure of a magnetic field is possible with a fluxgate magnetometer.