This is a fascinating and fully functional volvelle. Galluci included fifty-one different volvelles in the Theatro del Mundo. These were used to solve problems concerning the calendar, tide tables, the rising and setting of the sun, moon, or stars, and the positions of planets. This example consists of an engraved circular calendar, inside of which is mounted a moveable disk engraved with 30 divisions and the zodiac sign Sagittarius. An additional moveable pointer (Index) is then mounted at the center with a red satin ribbon. Because of their delicate nature most volvelles have not survived intact.

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Condition: A

Bit of surface soil, still very good with a crisp impression and sturdy paper.