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 6.75" long, each of two laminations, 0.5" deep at ends, each having an auxiliary needle, semi-circular in shape, attached to the centre. The two outer needles are 4" long and 0.5" deep and have two laminations each mounted 2" apart and attached to a light metal ring which is screwed to the card.
Pivot- Inverted type mounted in double gimbals dia. 1.75", attached to the two central needles by brass brackets. The pivot pin is adjustable vertically by being threaded.