Gunter quadrant for latitude 51° 32' North.

This is a round boxwood quadrant and almanac with a brass index arm on the almanac side and a brass loop and suspension ring. On the reverse side are scales for calculating the amplitude of the Sun and its rising and setting set in concentric circles. From the rim inwards, there is a Zodiac scale; a declination scale, marked 'Declina:'; a degree scale, marked 'Amply:'; another degree scale marked 'Riseing' and a date scale in four circles divided to month. Pivoted at the centre of the circles is a brass index arm that extends to the edge of the disc.

On the obverse side, the quadrant is engraved within a heart. Within the degree scale is a scale marked 'Shaddoes'. There are lines of declination from the Equator to the Tropics for every degree, a declination scale on the right hand side and numbered hour-lines. In the right-hand side of the outlined heart, there is a table described as 'An Almanac foreuer'.

This instrument is described and explained in John Brown's 'The Description and Use of the Carpenters-Rule... To which is added, the Use of a (portable) Geometrical Sun-dial, with a Nocturnal on the backside (1662)'. The book describes a nocturnal on the reverse side rather than the table for sunrise and sunset and length of day that appears on this quadrant. Two similar quadrants in ivory are in the British Museum (registration nos.1894, 6-23.3 and 1923, 2-6.2), one of which is signed 'John Browne'. Another ivory quadrant is in the Time Museum in Chicago (see A.Turner, 1985). The present instrument is signed 'Latitude 51 32 J B Londini fecit' on the obverse side.

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