ABSTRACT
The methods of water-divining cited by Vitruvius sound chancy, but they undoubtedly are based on experience. Pliny records the same procedures (Natural History 31.43-49). Since water usually was drunk without any chemical treatment in antiquity, the natural flavour and salubrity, affected by the character of the subsoil and the type of source, were
Vitruvius, On Architecture 8.1.1-2, 4-6
Water is an absolute necessity for life, for pleasure, and for daily use. It will be more convenient if the streams are out in the open and flowing, but if they do not flow out above ground, then sources must be sought and collected underground. The following technique must be tried: one lies on the stomach before sunrise in the places where it is to be sought and, with the chin resting on and supported by the ground, examines the area. In this manner, when the chin is not moved, the glance will not wander higher than it should, but with precise definition it will describe a level line throughout the area. Then excavation is to be carried out in those places where mists curl upwards and rise into the air, for this sign cannot appear above dry ground.
