Bowl-Brass, painted black, filler plug at side of bowl, expansion chamber at base of bowl, centre part of base of bowl glazed with opaque glass so that the card can be illuminated from below. Inside of bowl painted white and fitted with two lubber lines 90 degs apart. Mounted in gimbal ring.
Card-Mica, centre part black, outer part white with black markings, graduated to 1/4 points and to 360 degs. Diameter 6.5" (16.5cm)
Pivot-Pivot stem secured to base of bowl on bridge across diameter.