Construction of Roman aqueducts
The aqueducts required very careful planning before building, especially to determine the water source to be used, the length of aqueduct needed and its size. Great skill was needed to ensure a regular grade, so that the water would flow smoothly from its source without the flow damaging the walls of the channel. As the need for water grew, extra sources would be utilised, very often making use of existing structures as with the Aqua Claudia and Anio Novus in Rome. The problems of aqueduct building and use are described by Vitruvius and Frontinus, the latter producing a long report on the state of the Aqueducts of Rome in the last years of the first century AD.
Several surveying tools were used in the construction of Roman aqueducts, one example being the chorobates. The chorobates was used to level terrain before construction. It was a wooden frame supported by four legs with a flat board fitted with a water level and wooden arches to support the vaults. Another tool used in the construction of the aqueduct was the groma. Gromas were used to measure right angles. A groma consisted of stones hanging off four strings perpendicular to one another. The instrument which is the forerunner of the theodolite was known as the dioptra, and was used to measure vertical angles.
