Augury was the practice of foretelling the future largely from the flight of birds. Many different outcomes could be predicted depending on the number, flight path, and type of birds observed at certain times of the year. It was practised mostly in the Roman Empire, where it was sanctioned by the government. Persons who practised augury were called augurs.
Many local governments in ancient Rome retained official augurs. In August 79, the Tenth Doctor and Donna were opposed by such a person, Lucius Petrus Dextrus, in Pompeii, although his visions of the future were not derived from augury itself. (TV: The Fires of Pompeii)
Augurs foretold the future in stone circles called Gorsedds. (TV: The Stones of Blood)
A stone that fell from Gallifrey, designed to preserve it from the Last Great Time War, was referred to as an augur's stone. (AUDIO: The Oncoming Storm)