Facsimile diptych dial for latitude 42° North. This wooden dial consists of two leaves that fold together when not in use. The inner surfaces are lined with paper. There is an elaborate compass rose on leaf Ib with a fleur-de-lys above. Three black lines point to marks near the attachment of the string gnomon, marked S, C, M respectively (these may have indicated different positions of the gnomon for different latitudes on the original instrument).

On leaf IIa is a compass rose surrounded by markings for a horizontal dial. The cardinal and quadrantal points are indicated by Italian initials for the eight winds (apart from East, which has a cross). Set above the compass rose is a small compass, with 'WEST GERMANY' printed on the compass plate.

This imitation dial was based on diptych dials in the Museo di Storia della Scienza in Florence, but was modified from the original designs so that it could be used with reasonable precision in any part of Italy. The accompanying booklet provides a brief history of sundials and explains the method of use of this instrument, including the adjustments necessary for reading mean time.

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