A VERY RARE WILLIAM IV LUNAR WEATHER PROGNOSTICATORPUBLISHED BY C. UPJOHN, EXETER, TO THE DESIGN BY HENRY TROAKE, TOPSHAM, CIRCA 1831The 15 by 13 inch printed paper panel with aperture for month of the year adjted via a wooden turn to top, over dial with brass hand inscribed ENGAGEMENT and revolving disc annotated with radial days of the weeks four times set onto a dial with thirty-five divisions labelled 1 to 31 for date of the month, flanked by explanation passages providing the purpose of the instrument, the centre with two dials for SUMMER and WINTER flanking title WEATHER PROGNOSTICATOR each with outer twenty-four hour clock dial and centre divided into twelve sectors printed with varying weather predictions and with four brass setting hands engraved NEW, FIRST, FULL, LAST, the lower section with fourth dial again annotated 1 to 31 and with four brass hands the first labelled NEW and the others with symbols for waning, full and waxing moons, flanked by tree pairs of panel enclosing text passages providing additional information, the bottom edge with title panel Through all the lunations of each year for ever over inscriptions Published by C. Upjohn, Bookseller, Exeter; Designed and improved upon the system of the late astronomer Sir W'm Herschel by Henry Troake of Topsham, 1831; Roper, Sculp. Exeter, set within glazed case opening at the front for access.The exterior 44.5cm (17.5ins) high, 39.5cm (15,5ins) wide, 4.5cm (1.75ins) deep overall.Provenance: The exhibition collection of Barometer World Meum, Merton, Devon.The current lot explores the influence the moon may well have on weather conditions and draws upon the observations of Sir William Herschel with regards to patterns indicating a possible relation between the age of the moon and the weather. The calculator is designed to be entirely hand-set with the operator having to know the full date, age of the moon and importantly the time of day the moon transitions from one phase to another. The passages explain how the calculator should be ed and includes caveats regarding the difficulties of weather prediction during spring and autumn due to the irregular nature of conditions whilst transiting between the traditionally more settled summer and winter seasons.