Bowl- Brass (?) Painted black. Fitted with a glass bottom and a heavy balancing ring. Inside of bowl painted white, a black wire lubber line is fitted. An inverted scale of white on a black bckground runs round the upper part of the inside of the bowl, graduated to 360 degs. The verge glass is fitted with aperforated boss and a small reservoir with afiller plug at the centre. Mounted in black painted brass (?) gimbal ring.
Pivot- a metal tripod is fitted across inner surface of the bottom glass of bowl and the pivot, which is removable from below, screws through a gland at centre of glass and tripod. It carries a steel pivot point.