AN 18TH-CENTURY GERMAN SILVER PERPETUAL CALENDER-AIDE-MEMOIR, unsigned, the diverse: engraved with decorative scrolls and foliage, monthly calender of siants days, feast days, zodiac calender, hours of sunshine, sun rise and setting, the reverse: similarly engraved, the vovelle with scales for lengths of day, moon rise and moon set and zodiac calender, with four ivory tablets (one damaged), with the original fishskin covered case, with pencil--3¾in. (9.5cm.) long