AQ'IIEDUCT (Lat. aquas ductu.Q). an artificial course or channel by which water is con veyed along an inclined plain. When an A. is carried across a valley, it is usually raised on arches, and where elevated ground or hills intervene, a passage is cut, or, if necessary, a tunnel bored for it. Aqueducts were not unknown to the `creeks; but there are no remains of those which they constructed, and the brief notices of them by Pausanias, Herodotus, and others, do not enable us to form any distinct notion of their character. The aqueducts of the Romans were amongst the most magnificent of their works, and the noble supply of water which modern Rome derives from the three now in use, of which two are ancient, gives the stranger a very vivid conception of the vast scale on which the ancient city must have been provided with one of the most important appli ances of civilization and refinement, when nine were employed to pour water into its baths and fountains.
The following are the names of the Roman aqueducts, chronologically arranged: • 1. The Aqua Appia, begun by add named after the censor Appius Claudius about 813 n.c. It ran a course of between 6 and 7 in., its source being in the neighborhood of Palestrina. With the exception of a small portion near the Porta Capena, it was sub terranean. No remains of it exist.
2. Ado Vetus, constructed about 273 n.c. by M. Curius Dentatus. It also was chiefly underground. Remains may be traced both at Tivoli and near the Porta Maggiore. From the point at which it quitted the river Auio, about '20 in. above Tivoli, to Rome, is about 43 miles.
3. Aqua Marcia, named after the prtntor Quintus Marcius Rex, 145 B.C., had its sourer between Tivoli and Subiaco, and was consequently about 60 in. long. The noble arches which stretch across the Campagna for some 6 m. on the road to Frascati, are the portion of this A. which was above ground.
4. Aqua Tepula (126 n.c.) had its source near Tusculum, and its channel was carried over the arches of the last-mentioned A.
5. Aqua Julia, constructed by Agrippa, and named after Augustus 84 inc. Like the Tepulan, it was carried along the Marcia]] arches, and its source was also near Tuscu lum. Remains of the three last-mentioned aqueducts still exist.
6. Aqua Virgo, also constructed by Agrippa, and said to have been named in conse quence of the spring which supplied It having been pointed out by a girl to some of Agrippa's soldiers when in search of water. The Aqua as it is now called. is still entire, having been restored by the popes Nicholas V. and Pius IV. 1568. The source of the Aqua Virgo is near tlic Anio. in the neighborhood of Torre Salons, on the Via Collatina, and about 14 in. from Rome. The original object of this A. was to sup the Aqua Virgo is the best in Rome.
7. Aqua Alsietina, constructed by Augustus, and afterwards restored by Trajan, and latterly by the popes. This A., now called the Aqua Paola, is situated on the right bank of the Tiber, and supplies the fountains in-front of St. Peter's and the Fontana Paola on the Montorio. Its original object was to supply the Naumachia of Augustus, which was a sheet of water for the representation of sea-fights.
8. Aqua Claudia, commenced by Caligula and completed by. Claudius, 51 A.D. A line of magnificent arches which formerly belonged to this A. still stretches across the Campagna, and forms one of the grandest of Roman ruins. It was used as a quarry by Sextus V. for the construction of the Aqua Felici, which now supplies the fountain of Termini, and various others in different parts of the city.
9. Anio Norus, which was the most copious of all the Roman fountains, though inferior to the Marcia in the solidity of its structure; it was also the longest of the aque ducts, pursuing a course of no less than 62 miles. By the two last-mentioned aqueducts, the former supply of water was doubled. In addition to the aqueducts already men tioned, there was the Aqua Trajana, which may, howeveY, be regarded as+a branch of the Anio Novus, and several others of later construction, such as the Antoniana, Alex andrina, and Jovia, none of which were to be compared with the older ones in extent and magnificence.