Brass cruciform diptych dial for latitudes 21°-65° North for the equinoctial dial (45° North for the horizontal dial). The dial is split into four leaves. Leaf Ia displays a combined lunar volvelle and equinoctial dial with four concentric scales. It has a wind-ring marked with 16 points and the cardinal points named in French. Leaf Ib contains a table of latitudes, mainly for towns in France. There is also a strut hinged into a slot that is used for setting the latitude for the equinoctial dial and a peg at the top, which fits into a hole in the lower leaf when the dial is closed.

On leaf IIa the horizontal dial is set against the hinge of the dial, at the bottom of the cross (the string gnomon is missing) and the compass is set at the crossing point of the arms. The cardinal points are marked in French and an arrow is engraved for magnetic variation at 6° East of North. A latitude scale is set between the horizontal dial and the compass. Leaf IIb contains a table for calculating the age of the moon. The dial uses the arms of the cross itself as the gnomon.

Cruciform dials are a fairly rare form of multiple dial, always elaborately made and clearly intended for an aristocratic or ecclesiastical market. The time can be found from the shadows cast by the main upright on the arms of the cross and by the arms on the lower part of the upright, as well as by using the equinoctial and horizontal dials. The dial is signed 'BERNARDI DANIELIS'.

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