Dieppe magnetic azimuth dial for latitudes 50° North (0°-70° North for the equinoctial dial). This is a standard Dieppe magnetic azimuth dial (see related terms) except for the following details:-

It is made of tortoiseshell and there is no Dieppe-style ornamentation. The dial is split into four leaves. Inside the hour scale on leaf Ia are various Jesuit symbols: the initials 'IHS', a heart with three arrows projecting out from it; a cross surrounded by a sunblaze; and tongues of flame around the circumference. Leaf Ib displays an hour scale and a latitude scale. Leaf IIa is the compass card, displaying a table of latitudes for 20 European towns. It is surrounded by a painted border with maritime motifs including dolphins and waves. Leaf IIb does not contain a perpetual calendar. The centre of the volvelle and the spandrels are engraved with floral motifs. The outer edges of the dial are also engraved with floral motifs, incorporating birds and mythical beasts. The motifs on the outside of the upper leaf of this instrument show that it was made for a high-ranking member of the Jesuit order.

The use of tortoiseshell is unusual, although it also occurs in a similar instrument at the British Museum (registration no. 1871,11-15.1) and one at the MHS, Oxford (new inventory no. 33461). The quality of engraving is very high and the instrument is not only decorated with flowers such as poppies and lilies, but also with putti, dolphins and mythical beasts. It is engraved 'Charles Bloud ADieppe'.

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