A silver perpetual calendar/aide memoire, the obverse with rotating volvelle for the days of the month and central volvelle for phases of the moon, the reverse with single volvelle for months of the year displaying imoveable Feasts and Saint's Days, Zodiac sign, length of day, length of night, sunrise and sunset, decorated overall in cast foliage and grotesque animals, pivoting on rivet with twin ivory tablets -- 3½in.(8.75cm.)high, German, late 18th century