In a parchment on which the work of an early medieval author was written, scientists found a description of a meteoroscope – a unique instrument of an ancient astronomer, which until now was known only from indirect sources.
An article has been published in the journal Archive of History of Exact Sciences, the authors of which examine an 8th-century manuscript discovered in the Abbey of Bobbio in northern Italy. This manuscript contains the Latin text of the “Etymologies” of the early medieval scholar and one of the Church Fathers – Isidore of Seville.
The manuscript was discovered as early as the 19th century, when researching the scriptorium of the abbey. Several hundred manuscripts dating from the Early Middle Ages have been found there. It is believed that this scriptorium is described in Umberto Eco’s novel The Name of the Rose. The collection is now housed in the Ambrosian Library in Milan. The 8th century manuscript is, of course, an extremely valuable historical monument. But the authors of the new work claim that the book is actually even older and more valuable. Examination of the pages has shown that at least some of them are palimpsests. This is what they call manuscripts written on parchment that has already been used. During the Dark Ages, parchment was very expensive and the monks who worked in the scriptorium invented various methods to allow it to be reused.
Fifteen palimpsests were found under Isidore of Seville’s text, which had previously been used for three Greek scientific texts: a text with an unknown author on mathematical mechanics and a catoptric (a section on optics) known as the Fragmentum Mathematicum Bobiense (three leaves), Ptolemy’s treatise “Analema” (six leaves) and an astronomical text that was hitherto unidentified and almost completely unread (six leaves). Using multispectral imaging methods, the scientists were able to reveal the hidden ink and examine the text, accompanied by a number of illustrations. They claim that this manuscript belongs to the ancient Roman astronomer Claudius Ptolemy. In addition, the manuscript is unique, there are no other copies.
Ptolemy, who lived in the 2nd century in Roman Egypt (mainly in Alexandria), was one of the most significant scholars of Hellenism and Rome. As an astronomer he had no equal either in his lifetime or for many centuries afterwards. His monograph Almagest (originally titled Syntaxis Mathematica) is an almost complete collection of astronomical knowledge about Greece and the Near East.
Another Roman scholar, Pope of Alexandria (the years of his life are unknown, presumably III-IV century), wrote quite detailed commentaries on the Almagest, from which it is clear that Ptolemy’s work has not reached us in its entirety. For example, Papp mentions the meteoroscope, an ancient instrument designed to determine the distance to celestial bodies, a variant of the armillary sphere. The authors of the new study claim to have found in the palimpsest exactly that part of Ptolemy’s manuscript in which he describes the device of the meteoroscope. This device was a complex assembly of nine metal rings connected in a special way.
According to scientists, it can be used to solve a variety of problems, such as determining the latitude in degrees from the Equator, the exact date of the solstice or equinox, or the apparent position of the planet in the sky. Its diameter was about half a meter. The device of the meteoroscope, the research says, is described in such detail that you can go with this text to a good metal worker and he will assemble the instrument. At the same time, there are practically no recommendations on how to conduct astronomical observations. The latter is very strange for Ptolemy – the rest of his works demonstrate the pedantry of the ancient scientist.
But researchers have no doubts about the authorship: Ptolemy had a very characteristic style and vocabulary. The authors of the work hope to find a continuation of the manuscript in possible palimpsests in other manuscripts from the collection of the Bobbio Abbey scriptorium. The ancient parchment may have been divided into pages and used by several scribes working on different manuscripts.
Photo: A much older text Alexander Jones et al is hidden under a copy of a work by Isidore of Seville.