Portable horizontal dial for latitude 43° North. The dial-plate is octagonal and carries an hour scale around the rim depicted on a scroll. Between this and the compass are engraved the Equator and the two Tropics. Each Tropic is marked by a zodiacal symbol at both ends. 'Cadran Astranomique' (Astronomical sundial) is engraved near the Tropic of Capricorn. The hinged gnomon is shaped and engraved with acanthus leaves and folds flat when not in use. In it is a notch for use with the scale for Italian hours. On the compass, the cardinal points are named in Latin and North is offset 7° West of North to allow for magnetic variation. The needle is blued, with an open circle for North, and is surmounted by a brass pyramidal pivot. There is a glass plate over all.

The inclusion of Italian hour-lines and the Italian names for the cardinal points indicates that this dial was made for use in Italy. A latitude of 43° is close to that of Perugia (43° 08'), Piombino (42° 55') and San Benedetto (42° 57'); no other Italian town of any size lies near to the 43rd parallel. The time is read in Italian hours by marking the position of the shadow of the nodus among the hour-lines. The dial is signed 'N Bion A Paris' on the reverse side.

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