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.

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