Card- Mica covered with paper. White with black and white markings, graduated to 1/4 points, about one inch from edge is a circle of degree graduations with two rows of figures 0-9 quadrantally and 0-360 (for use with Gilberts azimuth circle).
Needle- Four heavy edge bar needles of laminated rolled steel, 2 x 7" and 2 x 5" long. They are mounted 1.75" apart and have bevelled ends, attached to a metal ring which is screwed to card. a light brass cross frame, attached to the two inner needles, is fitted at centre to carry pivot.
Pivot- Cone-shaped brass pivot cap with jewel at top, screwed through centre of cross frame.