Used for measuring electric current. It works by using a compass needle to compare a magnetic field generated by the known current to the magnetic field of the Earth.A "compass rose" type of horizontal full-circle scale, with 4 0-90 unit quandrants. Balanced, free-floating needle. Located centrally wired to a vertical coil. Horizontal distance scales, one each side and perpendicular to the core. All mounted on polished wood base, equipped with 3 terminal posts. Materials: glass, wood, metal.elementary, physics, experiment, galvanonometer, ballarat school of mines, scientific instruments