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Communication Dans Un Congrès Année : 2023

Why were scholars from Cyprus interested in the plane astrolabe in the 7th century?

Résumé

The ms. Paris BnF syr. 346 contains correspondence that bears witness to scientific exchanges in the 7th century AD between the monastery of Qenneshré (in northern Syria) and a Syriac Orthodox community on the island of Cyprus. These exchanges include the recent invention of Indian numerals, the Almagest, Ptolemy’s Geography, the Handy Tables and the astrolabe. My presentation will focus on the exchanges between Severus Sebokht, abbot of Qenneshré, and Basil of Cyprus, periodist, concerning the use of the astrolabe. Since the Cypriot community to which Severus Sebokht is addressing is interested in the astrolabe, I propose to draw the public’s attention to the concrete use they may have made of this instrument. I will rely in particular on an unpublished chapter of geography preserved only in one ms., Paris BnF syr. 346, as well as on an unpublished critical edition of the Treatise on the astrolabe attributed to Severus Sebokht. This presentation will also be an opportunity to highlight the high scientific level reached in astronomy and geography by the Cypriot community. Indeed, one of the advantages of the astrolabe is that it facilitates complex calculations allowing the position of a star to be associated with a precise time. The fact that the Earth moves in two circular motions (on the ecliptic plane when it rotates around the Sun, on the equatorial plane when it rotates on itself) makes the task of the astronomer wishing to make this association particularly complex. To determine the position of a planet at a given time, the astronomer must succeed in projecting ecliptic coordinates onto the equatorial plane. This projection required a complex and time-consuming arithmetic calculation, the final result of which was unlikely to correspond to reality at a time when the trigonometric instruments (notably the sine) developed by the Indians had not yet reached the Mediterranean. John Philopon (6th c.) and Severus Sebokht (7th c.) testify respectively in Greek and Syriac to the fact that it was possible to circumvent this difficulty thanks to a simple instrument: the plane astrolabe! The Syriac source even claims that the figures in the tables of ascensions (A1 and A2) attributed to Ptolemy result not from calculation but from the use of the astrolabe. In addition to the Syriac witness, I will rely on John Philopon’s critical edition of the Greek text (published by Jarry in 2015) to explore the potential of the astrolabe as a wonderful calculator.
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Dates et versions

hal-04368758 , version 1 (01-01-2024)

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  • HAL Id : hal-04368758 , version 1

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Émilie Villey. Why were scholars from Cyprus interested in the plane astrolabe in the 7th century?. Fourth International Conference on Byzantine and Medieval Studies, Mar 2023, Nicosia, Cyprus. ⟨hal-04368758⟩
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