Claudia and the Alexandrina, at Rome, important artistic structures. Here there were separate purifying and storing compartments for each class of structures supplied: in the Republican period there were only three — public fountains, baths, and private houses. But under the Empire the subdivision became much more elaborate. Certain very large single buildings, such as baths, had separate reservoirs, or tanks. The water was carried into private or public buildings by lead pipes through an official bronze joint stamped with its exact capacity, and serving as a meter. The conservation and regulation of the water supply, the exact allowance to individuals, corporations, and public buildings, was secured by a very careful administration of the water-works. This care was not only applied in Rome itself; but was coextensive with the entire line of aqueduct as it was tapped at intervals and used by towns, settlements, and private owners for drinking and irrigation. To assist the administration, a strip of land thirty feet wide was reserved along the entire course, as government property, and marked by boundary stones at intervals of two hundred and forty feet. The administration was under the care of the censors, and then of the quæstors and ædiles; but under Augustus the bureau was better organized, and put in charge of a Curator Aquarum, with his two assistants, his clerks, his consulting engineer, and his various classes of officials and of artisans comprising a familia of slaves: ushers, lictors, and criers, as well as pipe-layers, pavers, masons, levelers, measurers, inspectors, reservoir keepers, etc. As usual with Roman buildings, the aqueducts were built by contract, and the use of unskilled labor made their cost relatively small. The Appia is said to have cost $675,000. The repairing of the Appia and Anio Vetus, and building of the Marcia in B.C. 144-140, cost only about $850,000. Under the more lavish Empire the Claudia and the Anio Novus cost about $4,000,000, but none of the others were as expensive as these.
Among the Roman aqueducts, those of Rome itself possess the greatest interest, because of their number, length, and boldness of design and execution. Two of them, in fact, are still in use, and water from the very source that supplied one of them (Marcia) is now delivered to the city through a modern water-works system. Not only are they in remarkable preservation, but, most happily for engineers and archæologists alike, they are described in some detail by a Roman engineer who was water commissioner of Rome in A.D. 97, named Sextus Julius Frontinus, in his Two Books on the Water Supply of Rome. This work was first made available to English readers in 1899, through a translation by Mr. Clemens Herschel, an American hydraulic engineer, who gives not only the Latin text, but also a photographic reproduction of the oldest Latin MS. in existence, in the library of the Benedictine monastery at Monte Cassino. Besides all this, the book in question contains several chapters of comment by the translator, both on the aqueducts and the water supply of Rome in general. Mr. Herschel concludes that the capacity of the ancient Roman aqueducts has been greatly overrated, and that, instead of the 400,000,000 gallons a day given by some writers, based on Frontinus's calculations, "thirty-eight million gallons one day with another" is "a fair estimate at which to set the water supply within the walls of ancient Rome in A.D. 97, though the total ranged, no doubt, some 20,000,000 gallons per day either side of that mark from time to time. This would make about thirty-eight gallons per day per inhabitant, which is still a very large figure when use alone, not waste, is taken into account; and when, further, we consider that by far the greater part of the people undoubtedly used only such water as was carried to their homes in jars on the heads of slaves and other women." Still, Frontinus describes, nine aqueducts in use in his day, the main facts regarding which may be summarized as follows:
(1) Aqua Appia, built by and named after the censor, Appius Claudius, in B.C. 312. Its springs were between the sixth and seventh milestones from Rome, and its course was about 11 miles long. All but 300 feet was underground. The exact size of its channel is uncertain, but is given by several authors as about 2.5 feet wide and 5 feet high in the clear.
(2) Anio Vetus, constructed B.C. 272-270 by M. Curius Dentatus and Fulvius Flaccus. All but 1100 feet was underground. Remains may be traced both near Tivoli and near the Porta Maggiore. Its water is taken from the river Anio, about the twentieth milestone, three miles beyond Tivoli, and its course, which is very circuitous, is about 43 miles long. About 3.7 feet wide and eight feet high inside, of heavy masonry of peperino stone, plastered on the inside.
(3) Aqua Marcia, named after the prætor, Quintus Marcius Rex, B.C. 144-140, had its source in springs between Tivoli and Subiaco, near the thirty-sixth milestone from Rome, was over 62 miles long, carried into the city 195 feet above sea-level, so as to reach the top of the Capitol. Near its head it is 5.7 feet wide and 8.3 feet high, and further on it is 3 X 5.7 feet. This and the two preceding aqueducts were built of rough-hewn dimension stone, 18x18x42 inches, or more, while the later ones, except Claudia, were of concrete and brick. The greater part of Marcia was underground, but there were some long stretches on arches — over seven miles — some of which are still standing, and bear parts of two and three other aqueducts (Anio Vetus, Claudia, and Anio Novus) above them. This is especially the case near Tivoli, where there are superb viaducts and bridges alternating with tunnels. There are about six miles of arcades near Rome.
(4) Aqua Tepula, B.C. 125, leading from springs on the slopes of the Monti Albani, had at first an independent channel, on the arcades of the Marcia, 6 feet above it, or 201 feet above sea-level. It was 2.7 feet wide, by 3.3 feet high, and commenced not far from the eleventh milestone.
(5) Aqua Julia, the first imperial aqueduct, constructed by M. Agrippa, under Augustus, in 33 B.C.. 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 Marcia, about 212 feet above sea-level. Its channel was 2 3 feet wide and 4.6 feet high. 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
