Diptych dial for latitude 48° North. The dial comprises two leaves that fold together when not in use. Leaf Ia features a windrose with 16 points, on which the winds are named radially in Italian and Latin around the edge. On leaf Ib is a lunar volvelle with a rotatable disc featuring an aspectarium The fixed scales carry two hour-circles and a lunar-age scale and are named 'INCREMENTVM ET DECREMENTVM LVNAE' (Waxing and waning of the Moon). On the rotatable disc are two hour scales, an aspectarium and a circular aperture allowing a view of a pictorial display of the phases of the Moon. The hour-circle is cut away around the 'XII' for a pointer which moves over the lunar-age scale.

Leaf IIa contains a horizontal dial. It has an hour scale and a compass set at the centre of the dial-plate with the cardinal points marked in Latin. Magnetic variation is marked at 7° East of North and a simple brass gnomon, for latitude 48°, is set over the compass with a spring-loaded hinge. Leaf IIb displays a table of latitudes in three columns for places primarily in Eastern Europe, despite the fact that the single horizontal dial is set for a specific latitude. It is unclear how this could be used with the dial.

This is one of the very few extant examples of metal diptych dials. It is signed 'CHRISTOPHORVS . SCHISSLER . IVNIOR . . FACIEBAT . . AVGVSTA . . ANNO . . 1582'.

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