(5) Aqua Julia, the first imperial aqueduct, con structed by M. Agrippa, under Augustus, in 33 me., took water from springs near the source of Tepula (twelfth milestone), and was mixed with the latter to cool it, and entered Rome on the arcades of the about 212 feet above sea level. Its channel was 2.3 feet wide and 4.6 feet Portions of Marcia, Tepula, and Julia, one above the other, are still in existence at Porta Tiburtina.
(6) Aqua Virgo, B.C. 19, also constructed by Agrippa. Aqua Vergine, as it is now called, is still entire, having been restored by Popes Nicholas V. and Pius IV. The source of the Aqua Virgo is near the eighth milestone, only 80 feet above sea-level; its channel was 14 miles long, and it entered the city 13 feet lower. The channel was about 1.6 feet wide and 6.6 feet high. It still supplies the famous Trevi foun tain and others.
(7) Aqua Alsitqina, about A.D. 10, constructed by Augustus, now called the Aqua Paola, starts at a pond near the fourteenth milestone, and sup plies the fountains in front of St. Peter's and the Fontana Paola, on the Montorio. Its original object was for irrigating purposes, and to supply the Naumachia of Augustus, which was a sheet of water for the representation of sea fights. Its water, which was undrinkable, reached Rome in a channel 24 miles long, about 55 feet above the sea, the lowest level of any.
(8) Aqua Claudia, A.D. 38-52, commenced by Caligula and completed by Claudius, starts near the thirty-eighth milestone and is about 45 miles long. Its line of nearly ten miles of magnificent arches still stretches across the C'ampagna, and forms one of the grandest of Roman ruins. At its upper end its channel was 3.3 feet wide and 6.6 feet high. When it reaches the Campagna it carries the Anio Novus (see below), the lower aqueduct being of dimension stone and the upper of brick, lined with concrete. The water of these two aqueducts reached the Palatine 185 feet above the sea; but at Porta Maggiore the water in Anio Novus was at an elevation of 230 feet and Claudia. 9 feet lower.
(9) Anio Yorus, also A.D. 38-52, was nearly 62 miles long, thus being the longest of the aque ducts, and starting at the Anio, near the thirty eighth milestone. Its channel had a width of 3.3 feet and a height of 9 feet. Some of its arches are over 100 feet high, and its ruins are as superb as those of the Claudia, the two com bining before entering Rome.
Aqua Trajana, built in A.D. 109, started at Lake Bracciano, was about 40 miles long, fol lowed nearly the same route as Aqua Alsietina and its waters join to form the supply of the present Aqua l'aola. It was used for supplying
the .1:mien1um and the Trastevere. In A.D. 226 an eleventh and last aqueduct was built, called Aqua Alcrandrina, to supply the Campus Mar tins. The other aqueducts sometimes credited to old Rome were probably branches of some of the eleven.
Although stone continued in use for aqueducts under the Empire, concrete with opus reetirula lum and concrete with brick were used both in various parts of Italy and even in Rome itself, especially in the Aqua Alexandrina and Nero's additions to the Claudia. There remain many imposing Roman aqueducts in different parts of the Empire. The high viaducts and bridges 'in Frame, such as those near Nimes, C'aho•s, and Lyons; in Spain at Segovia, MOrida, and Tar ragona ; at. Constantinople, at Beirut, at Cherchel and Carthage arc especially imposing —higher and holder than anything at Rome; some have two, some three superposed stories of arcades, with a total height of between 100 and 300 feet. The Pont du Gard and the aque duct of Segovia are the finest in existence. The stonework in the provinces is even superior to the average in Rome. The following examples may be mentioned: Italy: Minturme (fine opus reti culatum, very deeorative), Genoa (very early, e.2I0 n.c.), Puteoli, Pompeii, Termini in Sicily.
Gaul: Nimes (Pont du Gard), Lyons (4 aque ducts in opus rctieulatum, with siphons and bridges), Metz (with a great bridge of 114 arches), Paris (3 aqueducts of late Roman date), Frejus (a superb example, built under Claudius, 30 miles long, with many arcades), Antibes (2 aqueducts, one still in use), Arles, Marseilles, Aix, Vienne, Autun, Besancon, Poi tiers (41, Cahors (a superb three-storied via duct), Toulouse, and many others. Gerniung: Mainz, Treves, Cologne, Solicinium, Windisch. Spain: Segovia (built under Trajan, 12 miles long, with a superb viaduct of 119 arcades, 818 yards long, in two stories), Tarragona (built in the Republican Period, •.210 D.C., 6 miles long, with magnificent two-storied viaduct of 11 and 25 arches), Chel•a, Seville.,MC.rida (2 aqueducts, one still in use; the other by Augustus, with a viaduct of three stories), Consuegra, Calahor ra. Portugal: El•as, Evora, Beja. Africa: Tebessa, Constantine (3), Tipasa, Cherchel (Casarea), Carthage (Punic and Roman), Slakter (with a viaduct). Asia: Ana zarba. Beirut (with a bridge), Palmyra, Baal bek, Petra, Sinope, Nicomedia, Antioch, etc.