Universal equinoctial dial for latitudes 0°-90° North. This dial is set on a circular brass base which is signed ‘G. Adams. No 60 Fleet Street London’. It is supported by three levelling screws, two of which are inscribed with a capital ‘A’. The inner section of the base, which carries both the compass and the dial, is free to rotate within the outer section. A vernier scale is engraved on the outer section and on the inner section is a degree circle within which is a scale for the equation of time.

Set into the base is a silvered compass which has an elaborately decorated eight-point rose marked by English initials. Two brass bubble levels are set into the well of the compass. Above the base, the hour ring pivots within a vertical brass semicircular arc supported by a tripod base with scrolled legs. The latitude arc is attached to the hour-circle at right angles and also holds the gnomon.

This instrument has similarities to the universal equinoctial ring dial, with its central latitude arc and rod gnomon carrying declination scales. However, it has a compass for orientation and the time is shown by the shadow of a rod rather than a dot of light shining through a pinhole. George Adams (d. 1772) was responsible for many of the pieces in George III’s collection of instruments, and this dial demonstrates the high quality of his work.

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