Mechanical equinoctial dial for latitudes 37°-65° North. The dial has a square brass base supported by three turned levelling screws. The latitude scale along the meridian line is divided [37°]-55°, down the centre of which is a slot in which a small brass rest is free to move. At the North end of the base-plate is a triangular plumb-bob support that is pierced for the admission of a brass plummet and bob. Hinged to the North end of the base-plate is a toothed hour-circle. A pivoted strut is attached to its underside, which is used to set the latitude of the instrument. Pivoted to the centre of the hour-plate is an index arm with a pointer at one end and a minute-dial at the other. Screwed to the index arm is a declination quadrant, which also functions as a support for the pivoted alidade. The alidade carries two pinhole sights and the end that moves over the declination scale has a pointer to mark the declination.

This instrument is clearly unfinished since most of the decoration only consists of what appear to be very basic guidelines. The working parts of the dial, however, are all in place. The beginning of the latitude scale at 37° North perhaps reflects the fact that this latitude covers the southern part of Sicily. The dial would therefore be available for use in all parts of Europe, but in no regions further south.

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