a celebrated Greek philosopher and mathematician; first author of the famous system of atoms and vacuums, and of the hypothesis of storms; since attributed to the moderns. He flourished about 428 B.C.

LEUCOGÆUS, in Ancient Geography, a hill situated between Puteoli and Neapolis in Campania, abounding in sulphur; now Alumera. Whence there were also springs called Leucogæi fontes; the waters of which, according to Pliny, gave a firmness to the teeth, clearness to the eyes, and procured a cure in wounds.