Bowl-Black painted brass 2.6" (6.5cm) deep, filler plug at side, annular bubble trap below verge ring, glazed bottom. Heavy balancing ring attached to bottom of bowl on three legs. Inside of bowl silvered with black wire lubber line mounted on a white plastic(?) strip attached to side of bowl. Mounted in black painted brass gimbal ring, 11" (28cm) diameter.
Card-diameter 6.25" (15.9cm). Perforated aluminium, graduated to 360 degs. Attached to large aluminium float at the centre.
Needle-Four cylindrical; two x 3.25" (8.3cm), two x 4.75" (12cm) long, mounted in float below card.
Pivot-Stem attached at centre of glass bottom of bowl, the rest of unit is unsighted.