Bowl- Brass bowl painted black and glazed top and bottom. There is a filer hole on the side and four expansion chambers are also on the side. A diameter bar at the base of the bowl supports the pivot arrangement. A black lubber spike projects horizontally from the inner side of the bowl. the bowl has a gimbal ring.
Card-A transparent card with a painted white and black centre, with the black markings graduated to 16 points. the transparent rim is graduated is graduated quadrantally in degrees. the card is 4.5" (11.4cm) dia. and is attached to the float by a wire framework.
Needle- Two needles in tubular holders are attached to the wire framework beneath the card 3" approx. length.