The Dioptra of Hero of Alexandria

Abstract

Hero of Alexandria flourished in the late first century AD, and a considerable number of works on mechanics and applied mathematics are associated with his name. The Dioptra, a relatively brief work describing a rather elaborate sighting instrument of that name, illustrates his interest in the meeting of mathematics and the practical world, and apart from a closely derivative late Byzantine text, it stands as the only surviving Greek treatise on land surveying. Hero's dioptra is presented in the scholarly literature on ancient surveying as both the most sophisticated instrument of its kind, equivalent to a modern theodolite, and as a clumsy and impractical device, of little use to practising surveyors. This chapter looks more closely at the form and capabilities of the dioptra, the methods of surveying proposed by Hero, and the reasons for the limitations in its design and use.