Bowl- Aluminium fitted with brass verge ring. Inside of bowl unpainted and fitted with a brass double bridge across diameter which carries the pivot and gearing 4:1 and an arm with a black spot. A pointer with a hole is pivoted under the verge glass and turned by a knob from above. Verge ring graduated anti-clockwise 0-16. Mounted in brass gimbal ring 5.7" (14.5cm) which is secured in an aluminium U-shaped bracket.
Card- Diameter 3.2" (8cm) Mica (?) covered with paper, divided into four quadrants painted : NE - yellow, SE - green, NW- blue, SW-red, and graduated to1/2 points.
Needle- Said to be two edge bar needles.
Pivot-Said to be double-pivoted; the upper pivot being incorporated in the brass bridge.