Body: A Bakelite molded ring 170 mm dia mounted with three sets  of winding either 2, 50 & 500 turns or 2,5 & 50 turns ,connected to brass terminals

Coil: the number of turns is clearly marked between the terminals

Base: the ring is mounted on a round Bakelite base which  rotates on an aluminum tripod base fitted with three brass leveling screws. .

A compass : is mounted on a Brass Pillar & is free to rotate upon it.