GERMAN PERPETUAL CALENDAR, 18th century, made of gilt and silvered brass, 1-7/8″ (4.7 cm) in diameter. On one side the rotatable “Calendarium Perpetuum” shows the days of the week (in German, and marked with their planetary signs) against days of the month, and has floral patterns hand-engraved in the open spaces. The other side gives, in seven readout windows defined by its rotatable disk, month of the year with its number of days, tabulation of the important saints’ and feast days in the month, sun¹s Zodiacal position, length of day, length of night, time of sun rise, and time of sunset. There is further floral engraving, as well as inclusion of a seated person amongst the vines. The Zodiacal signs are identified by amusing little hand engravings. A good example in very fine condition.
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David and Yola Coffeen both have enjoyed academic careers, as planetary astronomer and as linguist/educator. But since 1982 (yes, 1982!) they have been full-time dealers in early scientific and medical instruments, under the name Tesseract. Selling primarily by catalogue (over 100 issued so far) they also have a web presence at www.etesseract.com, and can be contacted at [email protected]