Dry card compass

Bowl-Brass painted black. glazed. White on inside with painted black lubber line. Azimuth circle with sights runs on three rollers. Fore sight of arch and thread with jet reflector. Back sight of slit and peephole with two sun filters and a prism. Glazing can be removed giving access to card. Set in gimbals.
Card-Mica covered with paper. Black with blue markings graduated to 1/4 points and quadrantally in degrees, plus crown. Jewelled pivot cap at centre with weight on underside. Diameter 6.5" (16.5cm)
Needle-Two edge bar needles attached to underside of card by brass framework. Length 5.52 (14cm)
Pivot-Brass stem with changeable steel tipped spike.
Set on ACO stand O.A.Height 11.75" (29.8cm)

Object Details

ID: ACO0033
Type: Dry card compass
Display location: Not on display
Creator: HM Admiralty
Date made: 1840
Credit: National Maritime Museum, Greenwich, London, Admiralty Compass Observatory
Measurements: Overall: 295 mm; Diameter: 295 mm