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Petrus Apianus

Astronomicum Caesareum

INTRODUZIONE

Owen Gingerich

Research Professor of Astronomy

and History of Science

Harvard-Smithsonian Center

for Astrophysics

[PETRUS APIANUS]

Astronomicum Caesareum [Ingolstadt, 1540]

ROSENWALD COLLECTION 678

The “Emperor’s Astronomy” from the private press of Petrus Apianus is one of the great masterpieces of sixteenth-century printing. In this large folio volume the paper instrument found its supreme realisation in a series of intricate volvelles, all hand-colored in the astronomer’s Ingolstadt printing shop.

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 1534 and 1540 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. Folios [B3] to FIII contain these devices. Embodying all the details of the geocentric Ptolemaic system, the volvelles and threaded charts provide a remarkably accurate graphical calculation of a planet’s position. 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. For example, the moving parts on folio [G5] conceal an entirely irrelevant base of an astrolabe, the fossil of a plan that was undoubtedly abandoned when Apianus realized how hard it would be to cut out all the lacelike paper structure required for its movable star chart.

Throughout the initial part of his book, Apianus gives detailed instructions for the operation of the volvelles, using as his examples the birth dates of the Holy Roman Emperor Charles V and his brother Ferdinand I, the dedicatees. In the chapters immediately following, Apianus shows how to calculate eclipses, and in particular the partial lunar eclipse of 15 November 1500 in the year of Charles V’s birth, the one preceding the birth of Ferdinand I on 15 October 1503, and the total lunar eclipse of 6 October 1530, in Charles V’s coronation year. Next Apianus turns to two ancient eclipses, one reported by Plutarch in the year in which Darius was defeated by Alexander the Great and the other reported by Pliny in the second century B.C. And then, in a pioneering use of astronomical chronology, he takes up the circumstances of several historical eclipses. This part concludes with several movable devices for an assortment of chronological and astrological inquiries. One of the most curious is a pair of volvelles for finding the hour of conception from the time of birth and the phase of the moon.

The second part of the Astronomicum Caesareum deals primarily with observational problems and their graphical solutions. Although moving parts have not been included in its design, this section is not without interest, because it depicts for the first time the fact that comet tails point away from the sun. Among the five comets observed by Apianus in the 1530s and described here is the one now known as Halley’s Comet.

The final page of the Rosenwald copy contains Apianus’s original coat of arm. As a result of this magnificent volume, Emperor Charles V granted the professor a new coat of arms (Apianus printed a replacement page, which is found in some of the copies). The emperor also bestowed some more unusual rewards on the astronomer for this typographic tour de force: the right to appoint poets laureate and to pronounce as legitimate children born out of wedlock.

The twentieth century has given its own characteristic honor to Apianus’s effort: in 1985 a copy of the Astronomicum Caesareum was auctioned for 80,000 dollars. Approximately 120 copies survive, probably the majority of the copies printed, since it is unlikely that anyone would throw away such a fascinating volume. Even in the sixteenth century it was a luxury book. Tycho Brahe records that he paid twenty florins for one, which would be roughly equivalent to 3,000 dollars. A few books printed after 1540 managed to include even more complex assemblies of paper disks, but none achieved the total elegance and splendor of this volume. A triumph of the printer’s art, the Astronomicum Caesareum truly remains an astronomy fit for an emperor.

Ringrazio il Professor Owen Gingerich per aver acconsentito a pubblicare la scheda che presenta la copia dell'Astronomicum Caesareum appartenente alla Library of Congress, Washington, Rosenwald Collection 678.

Per approfondire

https://www.basgriffioen.nl/maan/facsimile-van-astronomicum-caesareum-uit-1967-nummer-369-van-750/?fbclid=IwAR38fqRa9UcEAR0gebQ3vnf0FZeWn5Hf44jIwKB2oIrq-K-nMQLUBfAYAy0

https://www.youtube.com/watch?v=b6entG-BXcQ&t=11s&ab_channel=BasGriffioen

www.atlascoelestis.com

di FELICE STOPPA

Riproduciamo di seguito l'intera opera depositata presso la Biblioteca Nazionale Braidense di Milano ( AB XVIII 38) con il consenso della Biblioteca e su concessione del Ministero per i Beni Culturali e Ambientali con l'espresso divieto di ulteriore riproduzione o duplicazione con qualsiasi mezzo