Available Shapes & Sizes are :
Bar 50mm pair, Bar 70mm pair, Rect. 30mmx3mm, Rect. 27x8x3mm Cylindrical 5mm, Ring 38x8mm Blue, Ring 38x8mm Red, Rect. 43x18x7mm Disc 10mm/3mm, Ring 38mmx5mm, Disc 25mm/5mm, Disc 25mm/8mm Disc, 9mm/6mm, Cylindrical each, Rect. 40x25x6mm, Rect. 40x25x10mm Cylindrical 12mm, Ring 13mmx3mm, Ring 30mmx5mm, Ring 30mmx3mm Disc 18mm/3mm, Rect. 18x10x3mm, Disc 4mm/3mm pair, Disc 12mm/5mm Ring 20mmx10mm, Disc 20mm/10mm, Ring 18mmx5mm, U-shaped 1 tall
Comprising a stout bakelite box, 100mm dia, with aluminium dial graduated in degrees from 0 to 360, anti parallax mirror slot & replaceable steel pivot. The short magnetic needle has a jewel bearing & a light aluminium pointer designed for precise reading & maximum damping. One meter long single piece wooden nicely polished base with embedded two half meter scale reading from the centre of compass box i.e. zero at centre of both the scales. Complete with compass box & levelling screw.
A bakelite ring or bobbin is of 165mm diameter with 3 windings of 2, 50, & 500 turns. The magnetometer is supported on a brass tube fitted on an ebonite plate, which is free to revolve in the base of the instrument. The magnetometer & the ring can both be rotated independently of the base which is with levelling screws. The compass box consists of a bakelite base with metal dial of diameter 100mm graduated in degrees & with anti-parallax mirror. Cobalt steel magnet & aluminium pointer are mounted on special synthetic sapphire. The needle moves on special pivot. This combination makes the needle virtually frictionless.