A bakelite ring or bobbin of 165mm diameter with 3 winding of enameled copper wire of different thickness 2, 50 and 500 turns. The magnetometer is supported on a brass tube fitted on an ebonite plate. The magnetometer and the ring can both be rotated independently of the base which is with leveling screws. Compass box consists of a bakelite case with metal 100mm dia dial graduated in degrees and anti-parallax mirror. The needle moves on special pivot. The circular plate carries a set of four socket terminals for connection to the coils.