Barlow Wheel
A star shaped copper disc 90mm dia rotatable vertically on pair of adjustable centres & dipping into small mercury trough between the vertical limbs of a small horse shoe magnet on a wooden base 150x100mm. The disc adjustable vertically on a metal pillar 75mm high, which is connected to one of the two terminals mounted on the base. The other terminal is connected to the mercury trough. Operates on 4 Volts.
