Water supply and urban population in Roman Cyrenaica

A central archaeological and historical problem is that of population. It is reflected in the question often posed by the student or visitor of an ancient city: how big was X?; how many people lived here? The reply is unlikely to be more than an informed guess and, in most cases, a mere hazard, exposing a fundamental lacuna in historical knowledge. The problem of population size is not simply of casual interest; it affects almost every aspect of a balanced picture of life in ancient times. Explicit classical allusions to population figures survive in only a very few cases (Alexandria, for example, had more than 300,000 free inhabitants in the first century B.C., according to Diodorus). In their absence it is extremely difficult to assess the number of inhabitants of a city at a given time, a situation further complicated by the fact that in Roman times a city comprised not just a built-up area, perhaps defined by walls, but also a neighbouring territory which it owned. The inhabitants of the territorium were liable to be counted with the city dwellers, thus producing a definition of urban population which differs radically from our modern concept. Despite the inherent difficulties, demographic studies have periodically occupied the attention of a number of archaeologists and historians, and in recent years two major works have appeared. In The Economy of the Roman Empire Richard Duncan-Jones devotes an important chapter to the size of cities. After reviewing the various methods used to calculate the size of urban populations, he puts forward figures of his own, based principally on the interpretation of epigraphic evidence. As one of his examples has a specific Libyan connection, it is worth summarising here. The town concerned is Oea (modern Tripoli). Duncan-Jones applies an approach first outlined in 1886 by J. Beloch, in examining ancient records of large-scale gifts for public feasts or cash hand-outs (sportulae). These records provide important clues to the size of the urban population at the time of the benefaction. In the case of Oea, two pieces of evidence have been preserved. The first is given by Apuleius in the Apologia, a speech prepared for his defence (in a trial at Sabratha) against a charge of winning his Oean wife, Pudentilla, by magic.