Object Name: rectangular ivory diptych sundial
Dimensions: closed: 1.7 x 4.3 x 11.8 cm (11/16 x 1 11/16 x 4 5/8 in.)
Description: This is an unusual ivory diptych sundial in both elongated shape and design. It has a single pin gnomon dial showing Italian hours and two magnetic compasses.
1a: Medici coat-of-arms surmounted by a crown and supported by acanthus leaves. The rest of the space is filled with drapery, a running leaf border, and silver clasps engraved with leaves and scrollwork.
1b: Decorated with a grotesque consisting of a man's face with leafy hair, beard, and mustache. Bordered by a running leaf pattern and twisted rope design.
2a: Two magnetic compasses with paper inserts marked by hand in brown ink. The top compass gives the Italian names of 32 wind directions. The lower compass gives the French names of 32 points. The compass needles and retaining rings for the glass are present but the glass is missing. Between the compasses is a horizontal pin gnomon sundial for Italian hours, 12-23.
2b: Decorated with a simple geometric pattern.
Signed: on 2a: G G / F
Historical Attributes: This ivory diptych sundial was made by Giovanni Battista Guisti, Florence, for the Grand Duke of Tuscany, between 1558 and 1568.
Curatorial Remarks: Leaf 1a is engraved with a crown over the Medici coat of arms, which dates this dial before 1569, when the Grand Duchy of Tuscany was formed.
Provenance: Formerly Drecker Collection No. 210.
Related Works: G. L'E. Turner, "The Florentine Workshop of Giovan Battista Giusti, 1556-c.1575," Nuncius: Annali di storia della scienza, 10 (1995); 131-172.
Published References: Steven A. Lloyd, Ivory Diptych Sundials, 1580-1750 (Cambridge: Harvard University Press, 1992), cat. no. 82.