Marcus Schinnagel's Winged Polyptych of 1489: Astronomical Computation in a Liturgical Format

In 1995, the Landesmuseum Wurttemberg in Stuttgart acquired a large double-winged set of painted panels, in a format usually associated with altarpieces bearing Christian iconography intended for liturgical use in sacred spaces such as churches or chapels (see Figure 1). The central panel measures 140 ? 130 cm; when both sets of wings are opened, the overall width extends to more than 330 cm. The maker's signature appears prominently at the top of the central panel: Ego magister marcus schynagel alme universitatis crackoviensis. At the bottom of that panel we find a date: 1489. But unlike nearly every other known European winged panel painting in that period, the Stuttgart piece does not present liturgically inflected images. Instead the panels are completely covered with calendrical, astronomical and astrological material. Eleven separate astronomical tables can be identified, generally related to the Parisian Alfonsine Tables composed in the 1320s. Computistic tables offer information for determining dates of Easter and the other moveable feasts of the Christian calendar. Several prose texts give standard astrological information, nearly all copied verbatim from contemporaneous printed books. In the middle of the central panel are remnants of what may once have been large rotating vovelles, presumably parts of instruments for performing astrological or astronomical computations. Schinnagel's unusual polyptych presents an astronomical -astrological compendium for determining dates of the moveable feasts, casting and interpreting horoscopes, finding times of eclipses and syzygies, computing planetary longitudes, and for introducing its viewers to the mathematical structure of the late-medieval cosmos.But why the polyptych format? Why go to the trouble of painting these texts and numerical tables on large panels with moveable wings when a codex might convey the same information? Can other late medieval examples of non-codex or non-paper formats for astronomical compendia be identified? What does the content of the Stuttgart piece, as well as its format, tell us about Schinnagel's practice of astronomy and astrology? Can his sources be identified? How does the content of Schinnagel's polyptych relate to his autograph collection of astronomical and astrological texts preserved in British Library Add MS 34603? These are the questions that will guide our investigation. Schinnagel's polyptych, I shall argue, must have had representational valence, its meanings must have exceeded its use as a tool of computation. But whatever its valence, his compendium would find few imitators. Schinnagel's double-winged piece is a nearly unique artifact in the history of astronomy as well as in the history of art.Although his artifact is nearly unique, Schinnagel otherwise appears to have been a rather ordinary practical mathematician of the late fifteenth century, leaving biographical traces in several manuscripts and 13 signed incunable editions. Born around 1448 in what is now Kosice (about 100 km northeast of Budapest), Schinnagel probably matriculated at Cracow University in 1466 where he apparently became a master of astronomy.1 In 1487 in his earliest extant printed almanac he signed himself "in arte astronomia magistrum marcum schynnagel". In 1490 he referred to himself as "der freyen kunsten vnnd in sonder der astronomy doctor".2 By the next year he had moved to Swabia, as indicated by a verse in a practica for 1491 that he had printed in Ulm:Fur war den spruch hat gemachtGepracticiert vnd aus grund erdachtMaister marx schinagel ist er genantJn Schwaben wol erkantAin astronomum thut er sich nennenAin astrologiam gar wol erkennenAin arismetricus auch dabeyMit seinen kunsten ist er frey.3Starting in 1487, various editions of broadside almanacs and multi-leaved annual practica began to appear under Schinnagel's name, printed in Strasbourg, Basel, Ulm and Augsburg. In 149 1 , Schinnagel dedicated a practica, printed in Basel, to the Roman-German King Maximilian I; in 1493, another practica, printed in Leipzig and "Vienna, was dedicated to the Polish King Albert; several years later, an Ulm practica was dedicated to Duke Albrecht IV of Bavaria. …