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Volvelles are concentric paper or parchment circles used in medieval Europe to calculate the phases of the sun and moon.


"Sphaera Ioannis de SacroBosco Emendata" by Joannes de Sacro Bosco. Published in 1606.


Front Cover
Front Cover.
Title Page
Title Page.
Volvelle
Volvelle.
Volvelle
Volvelle.
Spine and Rear Cover
Spine and Rear Cover.