Early Astronomy in the University of Michigan Collections

Jofrancus Offusius

Our copy belongs to a group of nine extant copies of the first edition containing marginalia derived from the notes by Jofrancus Offusius, a Rhenish astronomer working in Paris in the 1550s. To be precise, our copy is part of a smaller group of seven copies that include planetary radices for the year 1550 at the bottom of the mean motion tables.

Shown here is an example of these annotations, including a drawn diagram, on a section dealing with how the distances of the Sun and Moon from the earth, their diameters, shadows in the path of the moon, and the axis of the shadow of the Moon, are all demonstrated together. ABC signifies the circumference of the Sun, and EFG depicts the Earth’s circumference.

De Revolutionibus (1543)


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