Card- Mica covered with paper, black with white markings. Graduated to 32 points with decorated East point, the outer edge is graduated quadrantally in degrees.
Needle- Flat bar type, 5.85" (14.9cm) in length, with square ends. Has an expanded centre aperture to accommodate pivot.
Pivot- Inverted type mounted in double gimbals in manner patented by George Alexander of Leith in 1813, and attached to needle by two screws engaging in gimbal rings.