Abstract

The general neglect of ancient surveying by classical scholars can be demonstrated easily. The third edition of the Oxford Classical Dictionary has no article on surveying. The great Real‐Encyclopädie has two short articles on the Greek dioptra but nothing at all on the Roman libra. A History of Technology has no section on surveying. Even the indefatigable Otto Neugebauer seldom mentions terrestrial surveying, and the best introduction to the subject is probably the chapter in Edmond Kiely's Surveying Instruments: Their History and Classroom Use , pages 18–44.Until now. In Surveying Instruments of Greece and Rome, M. J. T. Lewis has gathered and set out a wealth of material, suggested important revisions to several accepted views, and set the study of ancient surveying instruments and techniques on a firm foundation.The work is divided into three parts. In Part 1 Lewis draws on an impressive array of literary sources, plus archaeological evidence, later parallels, and his own trials with reconstructed versions of the dioptra and the libra, to trace the history, design, and capabilities of the instruments. He is particularly interested in the Greek dioptra. Here he brings to bear much new information , and he emphasizes both the impressive pioneering efforts of the Greeks and the close connection in Greek surveying between theoretical science—mathematics and geometry—and technical achievement. On the Roman side, Lewis points out that the chorobates would have been impossibly cumbersome in the field, and he argues convincingly that the libra was the instrument of choice for Roman surveyors. We do not know what this instrument looked like, but a close analysis of the word “libra” and of references to the instrument allows Lewis to suggest a plausible reconstruction. Relatively short but very interesting sections on the groma and on Vitruvius's hodometer complete Part 1.Having established the nature of the instruments, Lewis deals in Part 2 with various practical applications. Fine chapters outline the attempts of the Greeks to determine the circumference of the earth and, related to that, the heights of mountains. In the area of civil engineering, Lewis discusses examples of canals, aqueducts, tunnels, and roads. Here are some of the most impressive accomplishments of ancient surveyors: the very shallow gradients of some Roman aqueducts ; long tunnels, where occasionally we can identify a mistake in surveying; and the great straight stretches of Roman roads in Britain, where Lewis sets out a new theory on how they were surveyed and planned.In Part 3 Lewis provides translations of four extended passages on the design and use of the dioptra. He also translates 106 shorter passages drawn from a remarkable range of authors, inscriptions, and papyri and dealing with the various instruments and their uses. The translations are not word for word except where they need to be, but they are accurate and admirably clear. Lewis is the first to provide translations into English of the major texts on the dioptra , and this section will be a great help to scholars. My one regret is that he does not include the Greek texts on the dioptra. I understand the financial constraints; but few libraries have all of these texts, and including them would have added only some twenty‐five pages.Throughout this absorbing work, the level of scholarship is very high. Lewis's discussions of the evolution of the instruments and of ancient attempts to establish the circumference of the earth constitute an important contribution to intellectual history. Mistakes are few and insignificant. The author hopes that the volume will encourage further study, and it should. Quite apart from its importance for those who study ancient monuments and engineering projects, the book provides an excellent starting point for those investigating maps , precision instruments and their manufacture , and the transmission of scientific ideas in the Greco‐Roman world. Lewis writes engagingly, and his combination of first‐rate scholarship and hands‐on problem solving is irresistible