Bowl-Green painted brass, expansion chamber at base, filler plug at side. Inside of bowl painted white with two black lubber lines 90 degrees apart painted on side. Mounted in brass gimbal ring dia. 5.9" (15cm).
Card-Dia. 4" (10.2cm) White mica painted white with black markings. Graduated quadrantally in degrees and to 1/4 points. Decorated N point. Attached to white painted float at centre.