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The dioptra became the standard surveying instrument of the Greeks and, although no actual example has yet been found (or at least identified), we can discover a surprising amount about its design and employment by tapping sources hitherto almost untouched.
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.
Dioptra The dioptra was a different kind of level. It rested on the ground, and was finely adjusted by tilting and rotating the top part by means of precision screws, it could assess the angle of a stretch of aqueduct by looking through pivoting sights (O'Conner 1993: 45). See the illustration of a dioptra.
Dioptra is where the skill of the Roman surveyors came to the fore. The Dioptra consisted of a circular table affixed to a tripod or monopod, and this was calibrated with angles.
tises on the dioptra of Hellenistic Greece and the Corpus Agrimensorum of imperial Rome, our information is deplorably scanty. For some topics, like measuring cords and plumb-line levels which
The manuals—especially Hero's—give many examples of the dioptras use in land surveys, in engineering works, and possibly in mapping. The area of an irregularly shaped field, for example, may be calculated by dividing it into easily measured rectangles and right-angled triangles, leaving only the small residual slivers around the edge to be ...
It explores the history of surveying instruments, notably the Greek dioptra and the Roman libra, and with the help of tests with reconstructions explains how they were used in practice. This is a subject which has never been tackled before in anything like this depth.
