What’s better than a computer? A computer shaped like a dragon. In 1540, humanist polymath, mathematician, astronomer, cartographer, professor, and printer, Peter Apian (1495-1552) published one of the most lavishly illustrated scientific books ever printed. Dedicated to the Holy Roman Emperor Charles V and his brother, Ferdinand I, the Astronomicum Caesareum (Imperial Astronomy) contains 21 volvelles and 58 hand-colored woodcuts that involve some of the most spectacular computational dragons in the Rare Book and Special Collections Division.
A preoccupation with the functionality of tools from the present can sometimes result in a failure to appreciate the sophistication of instruments from previous centuries, but Peter Apian’s work is a reminder that the act of computing predates the use of a contemporary computer. In the Early Modern period, those individuals wishing to perform complex calculations of planetary motions could turn to a volvelle, a type of wheel chart made from paper or parchment containing rotating parts that functioned like an analog computer. Tied together at the center, the independent layers of the substrate (paper, in this instance) allowed the instrument to rotate around the central axis and the user to swivel the pointers and calculate the positions of the sun, moon, or planets. In his introduction, Apian claims to have taken eight years to create the Astronomicum Caesareum, and to have colored, cut, and assembled all of the instruments himself in his workshop.
The dragon plates, shown below, are some of the most famous and best loved apparatus in the Astronomicum Caesareum. In addition to offering a splendid potential tattoo design, the first draco volvelle invites its users to calculate the latitude of the moon. The central disk has two pointers: the dragon’s head (caput draconis), and the dragon’s tail (cauda draconis). Each corresponds to a lunar node, the point at which, in the geocentric Ptolemaic System, the orbit of the moon was thought to intersect the ecliptic, the sun’s apparent path across the sky as observed from Earth.
The elaborate draco volvelle can be used in conjunction with the text and numerical tables printed on the facing page. The first column of text provides an explanation of how to use the volvelle, and it cleverly employs the birthdays of Peter Apian’s patrons, Charles V and Ferdinand I, as examples. To see this instrument in action, turn to the video “Using the Astronomicum Caesareum Book” created by the Metropolitan Museum of Art, and watch the dragon disk turn.
The Rare Book and Special Collections Division has two copies of this magnificent work. The copy from the Lessing J. Rosenwald Collection has been digitized in full, so, now history-loving night owls can contemplate the Ptolemaic spheres from the comfort of their domicile at any hour. Those who prefer to be active during daylight hours and who also enjoy physical proximity to the Library of Congress during the month of July may wish to stop by the Rare Book Reading Room in LJ-239 during business hours to view a mini display of books that feature dragons. The display will be available until the end of the month.
Come take a look!
Sources and Further Reading:
Betteridge, R. (2017). “Astronomicum Caesareum.” National Library of Scotland.
Gislén, L. (2018). “A Commentary on the Volvelles in Petrus Apianus’ Astronomicum Caesareum”. Journal of Astronomical History and Heritage, 21(2&3), 135-201.
Fowler, I. (2023). ‘Astronomicum Caesareum’ with Ian Fowler. New York Public Library.
Karr, S (April, 2004). “Constructions Both Sacred and Profane: Serpents, Angels, and Pointing Fingers in Renaissance Books with Moving Parts” Yale University Library Gazette 78 (3/4), 101-127.
Martin, R. (2015). “Decoding the Medieval Volvelle: Made from Circles of Paper or Parchment, the Volvelle was Part Timepiece, Part Floppy Disk, and Part Crystal Ball.” Art Stories. Getty Museum.
Metropolitan Museum of Art. (2022). “Using the Astronomicum Caesareum Book.”
Poulle, E. (1984). Les Tables Alphonsines avec, les Canons de Jean de Saxe. Editions du Centre National de la Recherche Scientifique. Paris, Centre National de la Recherche Scientifique.
Wattenberg, D., and Archenhold, G. (1967). Peter Apianus and his Astronomicum Caesarum. Edition Leipzig. [Leipzig].
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