Ancient Roman instruments for surveilling like the Dioptra were simple yet allowed a high degree of precision for a multitude of uses such as Topography and Civil Engineering.
A Dioptra is an ancient Roman instrument for surveilling – it was used to measure angles in topography and civil engineering applications. It was first developed by the Greeks in the 3rd Century BC adopted and used by the Romans with incredible success. One can imagine that an instrument such as this would be fundamental to planning and accurately building roads, bridges and tunnels – a major element in Roman strategic supremacy. This ancient Roman instrument is similar to a Goniometer in concept (ie measuring angles), a Theodolite or the simple Groma.
This sketch gives an idea of what an ancient Roman Dioptra looked like – of the sort utilised to work out accurate angles in topography, civil engineering work or even in architecture.
The plumb lines allow the user to ensure the instrument is horizontal. Alternatively a water container could be used as a spirit level. Looking through the aiming site would allow you to point the instrument versus a distant landmark and measure angles on the horizontal table protractor marks.
Screw threads could be used to provide more accurate calibration adjustments and measurement.
Read more about it in our page about Ancient Roman Maps