This was the water-course, afterwards adjusted by Trajan, into which he introduced a new stream from the lake Sabbatinus, now the Lago Bracciano, and then the name of Alsietina was changed to Sabbatina. It is now the Aqua Paola, and supplies the fountains of St. Peter's and the Vatican. Some remains of the original work of Augustus (as is most probable,) may be seen without the Porta S. Pancrazio, in going towards the Villa Pamfili Doria.*

Independently of this work, Augustus, it would appear from one of the three inscriptions on the Porta S. Lorenzo placed over the Marcian aqueduct, that he repaired the channels of all the waters, that is to say, of the seven we have enumerated.

No other structures of this sort were erected at Rome until the time of Caligula, when the seven existing aqueducts being found insufficient for the increase of luxury and population, this emperor, in the 789th year of Rome, began two new ones. These were finished by the Emperor Claudius with great magnificence, and opened for use in the year of Rome 803. The first was named Aqua Claudia, and the second Anio Novus, to distinguish it from the other Anio, which was afterward called Vettis, or the Ancient. The source of the Aqua Claudia was from two fine springs called Cseruleus and Curtius, at a distance of thirty-eight miles from the city, on the Via Sublacensis, 300 paces within on a path to the left. The Aqua Claudia was next in quality to the Aqua Marcia. The whole length of this wonderful aqueduct was 46 miles and 406 paces, of which 36 miles and 210 paces were subterraneous the remaining 10 miles 176 paces were carried ;