For distinguishing one aqueduct from another there are many criteria. The first is construction materials. The earliest aqueducts are built of cut stone, the latest of brick. Miss Van Deman was famous for her precise dating of building materials; she was the only archaeologist in Rome who could date a brick by the _taste_ of the mortar. A second criterion is quality of workmanship. The Claudia, for example, is notoriously jerry-built: where abutments are found which should be solid, but are instead one block thick, filled in with earth behind, that channel belongs to the Aqua Claudia. A third criterion is mineral deposits. Thus the Marcia was famous for its purity; the crystalline lime deposits were quarried in the Middle Ages, polished, and used to decorate altars. The Anio Novus, on the other hand, is distinguished by a singularly foul deposit. A fourth criterion is directness of course: the older the aqueduct the more sinuously it runs; a channel found meandering by itself along the contours is likely to be that of the Anio Vetus. The total impression the aqueducts give is one of efficiency, organization, and heedlessness of expense, under the Republic as well as under the Empire. They were built with the spoils of wars or the tribute of provinces. The Marcia, built with the proceeds of the loot of Carthage and Corinth, cost 180,000,000 sesterces, or $9,000,000 uninflated. The Tepula, of 125 B.C., was perhaps built with the profits from the organization of the new province of Asia. From Agrippa’s time onward, and especially in Frontinus’ administration, the aqueduct service employed a large bureaucracy; overseers, reservoir-superintendents, inspectors, stonemasons, plasterers (the stone-built channels were lined with two or three coats of hydraulic cement), and unskilled laborers. Maintenance was a constant problem. Arches needed propping, filling in, or brick facing; piers needed to be buttressed or brick-encased. There was no attempt to produce high pressure: lead pipes would not have stood it, and for public use it was not necessary. There was no attempt to make the aqueducts financially self-supporting: their original building was one of the benefactions expected of successful commanders. Since these nabobs expected a _quid pro quo_ in the gift of power, the aqueducts are a symbol, under the Republic of irresponsible oligarchy, and under the Empire of increasingly irresponsible autocracy, though “good” Emperors like Augustus, Claudius, Trajan, and Hadrian had a hand in them. In Augustus’ reign were built the Julia, the Virgo, and the Alsietina. Trajan built a northern line from Lago di Bracciano to Rome’s Trastevere quarter on the right bank of the Tiber: part of its course runs under the courtyard of the American Academy. Hadrian executed major repairs, datable by the omnipresent brick stamps. But even good Emperors knew no way of financing such public works except bleeding the taxpayer. In municipalities, private capital was absorbed