Conférence du Dr. McMahon
« Measuring the Earth with Ptolemy in Byzantine Constantinople and Abbasid Baghdad: A Digital-visual Approach to Imperial Competition »
8 nov. 2023 — 14 h 30
Le département d’études anciennes et de sciences des religions présente une conférence par le Dr Lucas McMahon.
Tous et toutes sont les bienvenus.
La présentation sera en anglais.
À propos de la conférence
Description en anglais seulement.
Three inter-related tenth-century texts report that the emperor Theophilos (r. 829-42) established a long-distance chain of beacons linking the eastern frontier to Constantinople and that shortly thereafter the system was abolished by his son Michael III (r. 842-67). This talk discusses a brief moment in the history of imperial communication: the establishment, function, and mothballing of a medieval Roman long-distance optical telegraph line. While the telegraph was novel, how and why it was developed and used tells a story about competition between elites across borders, polities, and languages, the appropriation of the past, and efforts to shore up bonds between centre, heartland, and periphery of a state grappling with a long-term crisis. The study of the logistics of communication makes clear the logic of empire.
Did the telegraph work as described, and what was its purpose? The telegraph’s subsequent fame and alleged novelty was that it could transmit different messages, yet the (incomplete) list of those messages provided by Pseudo-Symeon raises questions about what authorities in Constantinople could actually do with that information. The first of these questions is addressed through what might be (hesitatingly) termed digital experimental archaeology, namely, a GIS visibility study aimed at identifying potential beacon sites to determine if Anatolia can actually be bridged by the number of beacons described in the tenth-century texts. Only a summary of the methods and results are presented in order to dedicate more time to the second question: why was the telegraph built, what purpose did it serve, and what does it mean?
The tenth-century accounts of the beacon line’s designer, Leon the Philosopher, set the origin of the telegraph as part of competition between the courts of Theophilos and the Abbasid caliph al-Maʾmūn. The beacon system was developed at a specific moment of intense intellectual rivalry in which the Abbasids were actively trying to claim the ancient Greek scientific heritage for themselves. Al-Maʾmūn was also attempting to improve upon Ptolemy’s measurement of the circumference of the Earth and had experiments carried out on the Tauros frontier as well as at Damascus when on campaign. These attempts are particularly relevant because the function of the beacon chain as described in the textual sources requires an understanding of Ptolemy’s calculations of longitude. While the telegraph had some value as a tripwire, it was unwieldy and only practical at a moment when emperor and caliph both took the field, which explains the efforts to shut it down after the 830s. More generally, however, the telegraph was ultimately an expression of empire and a claim on the ancient heritage in direct contravention to contemporary Abbasid efforts. Leon’s famous optical telegraph needs to be seen as the result of a moment of imperial competition, rather than any sort of normal form of optical communication.