“Glocalisation” of weight standards: The adoption of the Roman libra in the Eastern Mediterranean (1st c. BCE – 3rd c. CE)

Doyen, Charles [UCL]

Although it was assumed for a long time that Roman weights and measures had been introduced in Athens as early as the end of the 2nd century BCE, at the time of the adoption of the metrological decree (IG II² 1013), this transition certainly did not take place before the second half of the 1st century BCE. From the 1st century CE onwards, Roman denominations were used in the daily life of the Imperial Greek communities of the provinces of Thrace, Lower Moesia, Bithynia and Pontus, Asia and Syria. In Syria and in Bithynia and Pontus, weights dated by local eras or in reference to the reigning emperor allow us to follow the chronological development of this new weight system with great precision, from the 1st to the 3rd century CE. In Thrace, Lower Moesia and Asia, this chronology has yet to be defined thanks to archaeological contexts and prosopography, and by comparing weights and coins. Weight systems are sometimes structured around the monetary libra (326 g) and uncia (27 g) (e.g., in Lower Moesia and Asia), and sometimes based on a much heavier libra (from 350 g to 550 g). Certified denominations range from ¼ uncia (7 g) to 10 libras (ca. 3250–5000 g). It is also noteworthy that the Greek mina survived in Imperial times in small fractions (⅟₁₆ mina; ⅟₃₂ mina) or multiples of a libra. In all likelihood, the dichotomy that was already observed in Hellenistic times between a standard that used monetary weights (λίτρα ἰταλική, “Roman libra”) and a standard that used heavier commercial weights (λίτρα ἀγοραία, “commercial libra”) has continued in Imperial times. Until now, this fundamental aspect has been completely overlooked. It is therefore necessary to understand the exact articulation of these two weight systems in each province and their development over time.