28/07/2010

Modern surveying equipment may make the processes and capabilities of construction much easier. Techniques used by the Romans to build a crucial aquaduct in France, however, show that with the right minds and creative application, even the most rudimentary of tools could create the greatest feats of engineering.

A 50-kilometre aquaduct from Uzès to Nîmes in France, was created with a precise gradient of 1/3000, resulting in a total drop over its length of 17 metres.

The ancient surveyors and architects, Marcus Pollio Vitruvius and Sextus Julius Frontinus, detailed the surveying techniques they used for the waterway and, surprisingly, showed that a waterway was one of the less onerous tasks with which they could be charged.

In fact, there are many examples of Roman pipelines tunnelled through mountains from each side and meeting in the middle, and complex siphons across valleys were well within their capabilities.

The principle instruments were water levels, comprising a one metre long glass tube set in a wooden beam, and a three metre long beam with a channel for water grooved in the top.

They allowed experimental archaeologists accuracy of within 5mm over 50m distances, which compares favourably with modern methods.

They also used a basic plumb line, best exemplified by the groma surveying instrument that was used for sighting and setting out roads, aqueducts, buildings and land holdings.