Hydromancy

Webster's Dictionary

(n.) Divination by means of water, - practiced by the ancients.

Cyclopedia of Biblical, Theological and Ecclesiastical Literature

(from Ὕδωρ , Water, and, Μαντεία , divination), a species of divination, in which, by the aid of certain incantations, the images of the gods were seen in the water. The practice was brought from Persia, and employed by Numa and Pythagoras.