Bowl-Brass painted black, glazed top and bottom. Has a "screw" stop mechanism on side which operates, by means of a radical bar, a sleeve on the pivot stem, thus lifting the card. Painted white on inside with a black painted lubber line. Top glazing can be removed for access to card. Verge graduated to 360 degrees. Azimuth circle has two verniers graduated 0-30. Two sights on azimuth circle, fore sight is an arch and string with a jet sun reflector. Back sight is slit and peephole with two sun filters and prism. Circle moves in azimuth around a central brass pivot set in gimbals.
Card-Mica coverd with paper. Black with blue markings graduated to 1/4 points and quadrantally in degrees. Has a crown and jewelled pivot cap at centre. Weight on underside of card. Diameter 7.5" (19.1cm)
Needle-Four composite edge bar needles are attached to underside of card by brass circle and a weighted diameter. Length 2 x 7.252 (18.4cm), 2 x 5.25" (13.3cm)
Pivot-Brass stem with changeable steel tipped spike. Has sleeve for card stopping.