Accession No

1699

Brief Description

ivory diptych dial; French; 2/2 17th century

Origin

France

Maker

Class

dials

Earliest Date

1650

Latest Date

1700

Inscription Date

Material

ivory; metal (silver, brass, steel); glass

Dimensions

Special Collection

Holden-White collection

Provenance

On loan from The Fitzwilliam Museum, University of Cambridge. Donated by Charles Holden-White to the Fitzwilliam Museum. Holden-White collection no. 1935-53.

Inscription

Description Notes

Octagonal ivory diptych dial with silver and brass fittings. Borders of leaves decorated with engraved pattern.
Leaf Ia: equinoctial dial divided I - XII, I - XII, numbered by I, subdivided to 15 minutes. Polar dial divided 8 - 12, 1 - 4, numbered by 1.
Leaf Ib: southern half of equinoctial dial, divided as before. Silver lunar volvelle disc. Scale of latitudes divided 0 - 80˚, numbered by 10˚, subdivided to 5˚.
Leaf IIa: horizontal string-gnomon dial (string missing) for 48˚ N, divided V - XII, I - VII, numbered by I, subdivided to 15 minutes from VI - VI. Latitude arm in silver for leaf I. Inset compass with engraved hand-coloured paper card; 32 points marked with fleur-de-lys for North (card possibly later).
Leaf IIb: plain.
Compartment for gnomon in side of leaf II.

fair condition
string missing

References

Events

Description
The Diptych dial is a common form of portable multi-function sundial. Diptych dials were made popular by the instrument makers in Nuremberg during the sixteenth and seventeenth centuries. They are usually made of ivory with brass fittings, and are often elaborately decorated. The name of the device derives from the Greek diptychos for a pair of folding writing tablets, which the instrument resembles.

Diptych dials consist of two leaves hinged together, with a string ‘gnomon’ stretched between the inner surfaces of the leaves for casting a shadow. To use the device as a sundial the lower leaf must be placed parallel to the horizon and the upper leaf must be at a right angle vertically to it. The gnomon must then be aligned with the meridian of the place where it is being used by using the inbuilt magnetic compass. Time can then be read from the horizontal or vertical dial by the location of the shadow cast by the string gnomon.

In addition to the horizontal and vertical dials, diptych dials normally carry a number of other features, such as equinoctial dials, windroses, tables of latitude for adjusting the string gnomon for different locations, epact tables, lunar volvelles for telling time at night by the moon, and various pin-gnomon dials for telling the time according to Babylonian or Italian hours, or for calculating the position of the Sun in the zodiac.
27/05/2009
Created by: Joshua Nall on 27/05/2009

FM:39785