Accession No


Brief Description

diptych dial, by Fang Xiu-Shui, Chinese, 19th Century


China; Xiu Yi


Xiu-Shui, Fang



Earliest Date

Jan. 1, 1800

Latest Date

Dec. 31, 1900

Inscription Date


wood (boxwood); metal (brass); glass; rope (string)


length 119mm; width 77mm; depth 22mm; height when open 125mm

Special Collection

Robert Whipple collection


Purchased from Hony & Hill, Southampton.


‘Fang Xiu-Shui Xing An Xiu Yi’
[makers name] + [district] + [village]

Description Notes

Two boxwood tablets, hinged together.
Leaf Ia: lunar volvelle and equinoctial dial.
Leaf Ib: vertical dial divided for 5am-7pm
Leaf IIa: horizontal dial divided for 6am - 6pm. Central inset compass surrounded by four scales. Declination scales along side of leaf.
Leaf IIb: instructions for use and signature.


Joshua Nall; ‘Copycat sundials?’; Explore Whipple Collections online article; Whipple Museum of the History of Science; University of Cambridge; 2020:


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.
Created by: Joshua Nall on 27/05/2009


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