Bowl- Brass fitted with a glass bottom and a heavy balancing ring inside of bowl. Bowl has a mica-covered aperture cut inside, this is to illuminate the card. Inside of bowl painted white. Four lubber lines are deeply srcibed into the side of bowl, two wire lubber lines are fitted to bottom glass. The verge glass has lubber lines scribed on 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. Azimuth sight mounted in box lid has two folding arms 5.75" (14.6cm) long, one with a slit and clip attachment; the other with a thread. Mounted in gimbals in a wooden box 13 x 13 x 9.25" (33 x 33 x 23.5cm)-one side of which has a socket for a lamp. A curved metal plate slopes upwards from the lower edge of lamp aperture, this and interior of base, painted white to reflect light through bottom and side of bowl to card. Two carrying handles and two arms to lock gimbals are fitted to box. Lid of box also has a shallow hole fitted with a brass cover containing six x 1" needles.
Card- Dia. 8" (20.3cm) Kelvin type, light dry card, graduated quadrantally in degrees. North point 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 engages in cone-shaped jewelled cap at centre of card.