Diptych dial

Diptych dial for latitude 49° North. This miniature rectangular shaped dial consists of two leaves that fold flat when not in use. Leaf I is made completely of ivory and leaf II has a wooden core. Leaf Ia features a standard lunar volvelle (see related terms) except the edge is not scalloped. There is a single-lined border and red decorations in the corners. Leaf Ib features the vertical dial. The hour-lines, in blue, radiate from a double semicircle, inside which are two red snowflake motifs. There is single-lined border. Leaf IIa is as standard except the hour-lines are in blue and the numbers are in black. The string gnomon is attached between the inner surfaces of the two leaves.

The compass is offset 60° East of North to allow for magnetic variation. It has a blued needle, with a bar for North, and is covered by a glass plate held in place by copper wire. There are no dials for Italian and Babylonian hours. Two red snowflake motifs adorn the base of the gnomon. A brass pin for keeping the leaves aligned when closed is at bottom right of the leaf. Leaf IIb is bare apart from Leonhard Andreas Karner's makers mark - a hand. The leaves have a brass hook fastener and a brass hook for holding the dial open.

This composite dial is typical of the miniature diptychs being produced in the Karner workshop during the early years of the 18th century.

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

Object Details

ID: AST0254
Collection: Astronomical and navigational instruments
Type: Diptych dial
Display location: Not on display
Creator: Karner, Leonhard Andreas
Date made: Early to mid 18th century
Credit: National Maritime Museum, Greenwich, London, Caird Collection
Measurements: Overall: 14.5 x 35 x 44.5 mm

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