Epact Scientific Instruments of Medieval and Renaissance Europe

The nocturnal side, besides telling the time at night from the position of the stars, has a volvelle for predicting the age or phase of the moon. The reverse has two types of horary quadrant, a shadow square and a degree quadrant, all squeezed onto a small disk with their lines overlapping.

Museum of the History of Science, Oxford
Inventory number 55203

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