Liquid compass.

Bowl: Grey painted brass? filler plug at side; bottom has a detachable cover and carries stabilising weights; base of bowl has an annular ring of frosted glass surrounding an expansion chamber, the glass has six tubular lamps mounted around it. Inside of bowl painted white and fitted with four black wire lubber wires attached below verge ring. Verge glass carries a set of mirrored graduations 0 - 360 engraved on the glass and provision is made for quadrantal corrector magnets at centre of glass also a location stud for azimuth sight. Mounted in gimbal ring 12.6" (32 cm) dia. of unusual depth and with roller bearing pivots. Azimuth sight has frame containing sighting thread and reflector mirror (dark on one side, clear on other) at fore end and a prism and shades at the rear end. Shadow pin at centre.

Card: Diameter 7.5" (19 cm) Metal card? white with black markings graduated to 360 degrees with a second set of mirrored graduations 180 degs out of phase.

Needle: Unsighted.

Pivot: Unsighted.

O.A. Height 14.4" (36.5 cm)