Petrus Apianus Astronomicum Caesareum, Ingolstadt Petrus Apianus. Astronomicum Caesareum. Owen Gingerich. Research Professor of Astronomy. Harvard-Smithsonian Center. Astronomicum Caesareum [Ingolstadt, ]. Before writing and crafting the Astronomicum Caesareum , Apianus had pioneered in publishing books filled with ingenious movable devices, the so-called volvelles. Half a dozen of his works were produced at his own press in the university town of Ingolstadt, where he was professor of astronomy.
Production of the magnum opus must have taken the astronomer several years, for between and he published few other books. The great volume grew and changed in the course of the printing, eventually comprising fifty-five leaves, of which twenty-one contain moving parts and twelve more have index threads.
Among its variety of pages with moving parts comes first and foremost a set of planetary equatoria, paper wheels for finding the places of the planets within the zodiac.
The single most impressive page is folio [E4], the mechanism for the longitude of Mercury, which contains nine printed parts plus a complex hidden infrastructure to allow movement around four separate axes.
Rivaling this page in spectacular effect is the opening GIIIv-[G4] with a double cluster of lunar volvelles facing each other. Apianus did not originally plan to have the two sets of lunar volvelles facing each other; at the back of the Rosenwald copy are cancel leaves for folios GII an GIII according to an earlier conception for this section of the book. There also must have been other revisions in the design.
