ĒMISSĀRĬUM

( ὑπόνομος ), a channel, natural or artificial, by which an outlet is formed to carry off any stagnant body of water. Such channels may be either open or underground; but the most remarkable works of the kind are of the latter description, as they carry off the waters of lakes surrounded by hills. In Greece, the most striking example is presented by the subterraneous channels which carry off the waters of the lake Copais in Boeotia, which were partly natural and partly artificial. Some works of this kind are among the most remarkable efforts of Roman ingenuity. Remains still exist to show that the lakes Trasimene, Albano, Nemi, and Fucino, were all drained by means of emi aria , the last of which is still nearly perfect, and open to inspection, having been partially cleared by the present king of Naples. Julius Caesar is said to have first conceived the idea of this stupendous undertaking, which was carried into effect by the Emperor Claudius.