Dungal of Saint Denis
Born Probably Ireland, 2nd half of eighth century
Died Possibly Bobbio, Italy, after 827 and possibly 834
Dungal was a monk in deacon’s orders, poet, theologian, teacher, and the foremost expert on astronomy in Carolingian circles after the death of Alcuin in 804. He styles himself “exul, pauper et peregrinus.” Although some historians doubt whether the Dungal of St. Denis, of Pavia, and of Bobbio, in a putative time of four decades, are one person, the prevalent opinion is (Garrison 101) that they are one and the same (but not the same person as “Hibernicus exul”).
Even though Dungal does not answer Charles’s question directly, his lengthy text is an informative primer to lunar and planetary astronomy of the time, written for the astronomical experts at the court (Eastwood 122). Dungal also discusses the classical controversy between Plato’s heliocentrism of the inner planets and Cicero’s pure geocentric view. The circulation of the inner planets Mercury and Venus with respect to the sun was an important issue at the court, as is supported by a famous Carolingian book-painting (Leiden, Aratea-Planispherium, BKO after p.480), which shows the inner planets circling around the sun (thus a step towards Tycho Brahe’s system).
Dungal’s letter gives indirect information on the astronomical knowledge at the court of Charlemagne: obviously, there had been doubts at the court concerning two solar eclipses in summer 810, which were mentioned in several sources (Schowe 177/78), while lunar and solar eclipses had been observed and recorded for June 20 and November 30, 810, respectively. The occurrence of a solar and a lunar eclipse within 2 weeks and the appearance of another solar eclipse five or six lunations later seemed quite unusual. As a matter of fact, according to present knowledge (NASA), solar eclipses took place both on June 5 and July 5, 810, but they were not visible in Europe. Thus they must have been reconstructed according to some unknown rule (Newton 595/96). Since there was another “false” solar eclipse recorded for April 27, 811 (Springsfeld 242), which is six lunations after November 30, 810, the question arises as to how such a collection of hypothetic eclipses could be conceived.
There is an explanation: Pliny (Naturalis Historiae II, 57) mentions the possibility of a lunar and a solar eclipse taking place within 2 weeks and describes – relying on Hipparcos – further possible solar eclipses some lunations later. The eclipses undoubtedly observed by the Carolingians fit into the schema of Plinius. In addition the solar eclipses in question could be deduced from Pliny’s remark. But Dungal in his letter explicitly complains for not having Pliny’s natural history at hand. This is why hefails to answer Charles’ question directly. We conclude Pliny’s remark was the very source of “calculating” or reconstructing the “wrong” eclipses at the court, where Pliny’s text was in the library. This consequence supplements investigations by Eastwood and Graßhoff about Pliny’s strong influence on Carolingian astronomy.
After Charlemagne’s death in 814, Dungal was mentioned 823 in a “capitulary” of Lothair I and 825 in an imperial decree by which he was appointed “master” of the new cathedral school at Pavia, with jurisdiction over 11 subordinate schools in different cities of northern Italy. At the request of Emperor Louis the Pious, he wrote in 827/28 a refutation of teachings of Claudius of Turin, a pupil of Felix of Urgell and an exegete, dealing with Western iconoclasm. Since he bequeathed his valuable library of some 27 volumes to the Irish monastery at Bobbio (in the Trebbia valley, founded 614), among them the “Antiphonary of Bangor,” it is inferred that he spent his last days there. The date of his death is unknown.
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