Card-Mica covered with paper, white with black and white markings, graduated to 1/4 points. At centre of card is a hole 2" diameter to accommodate pivot gimbal.
Needle- Four heavy edge bar needles of rolled and hammered steel. The two central needles 6.5" long, each of four laminations, 0.5" deep at ends, having a semi-circular swell at the centre 1.25" deep. The two outer needles are 4" long and 0.5" deep and have two lamintations each. Mounted 2" apart and attached to a light metal ring which is screwed to the card.
Pivot - Inverted type (missing) mounted in a gimbal ring 1.75" dia. attached to the two cemtral needles by brass brackets. A very heavy gunmetal bell-shaped weight, dia. 1.75", is attached to centre of card, below pivot gimbal by two thumb screws so as to be detachable.