Compass dial for latitude 49° North. The brass dial is set into an ivory box with a screw-on lid over a revolving compass card. The dial-plate consists of a brass ring carrying the hour scale and an arc to support the gnomon at the centre. The brass gnomon is hinged, folds flat when not in use and is shaped and engraved on one side. There is a revolving compass card beneath the dial-plate, made of printed and painted card, displaying 32 points: the cardinal and intermediate points indicated by German initials. A central flower is surmounted by a brass pyramidal pivot and there is a glass plate over all.

On the inside of the lid is a lunar volvelle on which is a fixed disc with a lunar-age scale and an hour scale. Atop of this is a rotatable disc with a triangular pointer featuring an hour scale. This disc is pierced by a circle to allow a visual representation of the moon's phase. Stamped on the dial-plate are the initials 'CC' within a crown. The latitude for which this dial was made suggests that it may well have been produced in Nuremberg, a centre for the production of ivory sundials. Diptych dials were the most common Nuremberg dials, but compass dials were also produced by the same makers. A universal equinoctial dial stamped 'CC' is in the MHS, Oxford (new inventory no. 40253).

For more information regarding this dial please refer to the OUP & NMM catalogue, 'Sundials at Greenwich'.