Accession No
1704
Brief Description
ivory diptych dial, [German], first half 17th century
Origin
[Nuremberg (Nürnberg); Germany]
Maker
Class
dials
Earliest Date
1600
Latest Date
1650
Inscription Date
Material
metal (brass, silver, gilt brass); ivory; glass; rope (string - 2 sorts); paper
Dimensions
length 91mm; breadth 76mm; thickness 24mm
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. 1935-58.
Inscription
Description Notes
Diptych dial consisting of 2 ivory leaves hinged together and folding flat when not in use.
Leaf 1A:
Combined nocturnal and equinoctial dial. 2 circular scales inscribed on ivory: date scale divided to month marked by initial numbered 10-20-28, 30 or 31 as appropriate, subdivided to 2 days; hour scale divided I - XII, I - XII numbered by I subdivided to 15 minutes. Rotatable gilt-brass disc with hour scale divided I - XII, I - XII numbered by I subdivided to 30 minutes. Edge of disc toothed. Rotatable gilt index with folding end and pinhole sight
Leaf 1B:
Underside of equinoctial dial and lunar volvelle. Hour scale engraved on ivory divided I - XII, I - XII numbered by I subdivided to 15 minutes. Gilt brass rotatable disc set into leaf with hour scale divided [I] - XII, I - [XII] numbered by I subdivided to 15 minutes. Part of hour circle cut away to reveal lunar age scale divided [0] - 30 numbered by 1. Circular aperture in disc reveals pictorail representations of the phases of the moon (volvelle stuck). Latitude scale on right hand side of leaf divided [0] - 80 numbred by 10 subdivided to 2.
Leaf 2A:
Horizontal dial and compass. Compass set into centre of leaf with later paper compass rose, cardinal points marked by Italian initials, degree scale divieded [0] - 90 - [0] - 90 - [0] numbered by 10 subdivided to 5. Hour scale of dial divided V - XII, I - VII numbreed by I subdivided to 15 minutes. Dial used in conjunction with string gnomon which is set between the inner surfaces of the 2 leaves. Hinged gilt strut on right hand side of leaf for setting latitude for equinoctial dial.
Leaf 2B:
Horary quadrant and geometric square. Geometric square marked around 2 edges divided [0] - 60 - [0] numbered by 5 subdivided to 1. Degree scale for quadrant divided [0] - 90 numbered by 5 subdivided to 1. Outside this a date scale marked by signs of the zodiac and subdivided to 10˚. Straight hour lines marked for 5 a.m. to 7 p.m. in summer, 7 a.m. to 5 p.m. in winter with both Arabic and Roman numerals. 2 hinged brass sights set into top of leaf. Plumb-bob on string.
Holes on sides of lower leaf for holding plumb-bob and equinoctial dial gnomon (which is a replacement), with hinged silver covers. Silver hook fasteners and hook for holding dial open.
Condition fair; complete (gnomon for equinoctial dial is a replacement)
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:39996
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