Bowl- Brass, fitted with a glass bottom and has a heavy balancing ring inside bowl. Has a mica covered aperture cut in side to illuminate the card. Inside of bowl painted white. Four lubber lines are deeply scribed into side of bowl. The verge glass has corresponding lubber lines scribed on the underside of glass in form of a cross. Verge ring is graduated to 360 degrees. an azimuth sight locating spigot is mounted at centre of glass.
Card- diameter 8" (20.3cm) Kelvin type light dry card, graduated quadrantally in degrees. the north point is marked by a star and a crown and anchor device.
Needle- Eight needle magnets carried on thread framework below card.
Pivot Brass stem secured to glass base of bowl. Steel pivot point is screwed into top of stem and engagaes in cone-shaped jewejjed cap at centre of card.