Jewellery, Watches, Antiquities and Objects of Vertu

A brass universal equinoctial ring dial, by Picart & Cambray, the outer Meridional dial marked for 0-80 degree latitude for the northern and southern hemispheres and signed, the inner Equatorial dial marked for the time in Roman numerals, both inscribed to the reverse with the reference latitudes of assorted European cities, the central Declination swivel marked for the months of the year to one side and the signs of the zodiac and 25-0-25 scale to the other, supporting a sliding pinnule, the whole supported on a sliding suspensory loop, in semi fitted case, diameter 82mm. £400-£600

Equinoctial ring dials are early astronomical instruments. They consist of three rings oriented with respect to the local meridian, the planet's equator, and a celestial object (the sun). The instrument is suspended to align it with the vertical and is then rotated until a single light beam passes through the pinnule. This fixes the orientation of the instrument in all three axes, with the angle between the vertical and the light beam giving the solar elevation, so when adjusted for the latitude and the season it forms a sun dial, with the beam of light shining through the pinnule indicating the local solar time.