Horizontal dial

Horizontal dial for latitude 32° North. This dial comprises a rectangular brass plate supported by four shaped corner brackets (one copper, the rest brass). On the obverse side, the horizontal dial is marked with hour-lines for Babylonian hours, numbered in Indo-Arabic numerals. It has a hinged pin gnomon and a degree arc in the top right quarter numbered in 'abjad' numerals. An index in the shape of a narrow leaf is used to mark the 'inhiraf'. Four cardinal points are marked, as is the meridian line, giving the midday prayer curve (khatt zuhr). Around the edge is a simple decorative border. The compass is set into the plate, attached by two screws on the back and is marked with a magnetic variation for 15° West of North. The needle is blued, in the form of an arrow and surmounted by a brass pyramidal pivot. There is a glass plate over all.

On the reverse side is a table of 41 places in the Middle East with their 'inhirafs', in three columns. This horizontal dial, of which there is a very similar example in the Whipple Museum (accession no. Wh: 1482), gives the 'inhirafs' of its listed cities, unlike European dials which give the latitudes. Together with the latitude arc, it therefore serves as a qibla pointer, allowing its user to determine the correct direction of prayer for his latitude.

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

Object Details

ID: AST0499
Collection: Astronomical and navigational instruments
Type: Horizontal dial
Display location: Not on display
Creator: Unknown
Date made: 17th century
Credit: National Maritime Museum, Greenwich, London, Caird Collection
Measurements: Overall: 9 x 57 x 82 mm

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