by modern writers the Aqua Alexandrina, and erroneously attributed to Alexander Severus only.

The sources of this aqueduct are about three miles from Gabii in a watery meadow, nearly under La Colonna, the ancient Labicum. The reservoir of the Aqua Felice is in the same meadow, very near that of Hadrian. Several of the springs that supplied that of Hadrian were intercepted by the engineers of the Aqua Felice, who mistook these springs for those of the Aqua Marcia, shewing their ignorance of the line of the aqueducts. One of the streams, which is rapid and has a considerable body of water, is not used, because the water is of bad quality, and is so full of chalk that it is a petrifying stream. The first central castellum and piscina of Hadrian remains nearly intact, lined with the usual brickwork of that period, but much disguised in outward appearance. It is divided in the inside by a rough stone wall, as was frequently the case; the upper chamber to it has an external staircase added, and windows pierced in it, giving it now the appearance of a mere farm-house. Here the specus is perfect, and from hence it goes at first on a substructure, then on an arcade across the fields, and along the line of arcade to the Cento Celle. The part near the reservoir is destroyed, as is the opposite end near that place, but great part of the arcade in the intervening portion remains nearly perfect, and is one of the finest arcades of the aqueducts, extending for miles across the country between the Via Gabina and the Via Labicana. In some places it is double, one arcade over another, to cross a low valley or a stream. At about a quarter of a mile from the source, the specus is open in two places, so that a man can walk along it, being nearly six feet high and three wide. Small openings have been left on the sides of the specus at regular intervals to let the chalky water escape; and in falling from above it has left the marks of a small cascade in each place, in the form of stalactite, a solid deposit of chalk or lime or tartar against the side of the piers, down which it ran. These petrifactions continue all along the line as far as Cento Celle, and near that point there is a part where the stones and bricks of the arcade have been carried away for building-materials, and the masses of hard chalk remain standing up from the ground, in small pyramids, having very much the appearance of concrete respirators belonging to a subterranean aqueduct; but this appearance is deceitful. There is no pipe in them; they are merely petrifactions formed by the deposit of the chalk from the water.

By the side of the line there are some fine piscine and reservoirs, of Opus Reticulatum, at intervals, belonging to the time of Trajan

or Hadrian. Some of the arches near the sources seem to be earlier. The brickwork is so fine that it appears more like the work of Nero; but most of the work agrees well with the time of Hadrian, and Visconti states that an inscription of Hadrian' was found at the reservoir in his time, towards the end of the eighteenth century, and given up to the Borghese family, the proprietors of the ground, who also drained the lake of Gabii, with the aid of Canina the architect. This inscription is believed to have been sold to the French, with other things.

The character of the construction of the castella, or reservoirs, does not agree with the time of Alexander Severus, but suits perfectly well with those of Nerva, Trajan, and Hadrian, whose works are so well known. It is work of the first or second century, not of the third. It does not follow the line of the Via Gabina, but is carried at once to the south of it, towards the Via Labicana, and passes nearly parallel to it between those two roads until it crosses the Via Labicana at five miles from Rome, at the place called Cento Celle.

The bad effect of the petrifying stream was noticed by the engineers of the Aqua Felice, and, as that stream was carefully excluded by them, it now runs to waste through the meadows. This discovery was probably made before the third century, and the specus being then found to be choked up with stalactite, was restored to use on a higher level by Alexander Severus. Although the castella, or reservoirs, are all of the time of Trajan and Hadrian, the specus and the arcade to carry it is of two periods, the later portion of it being of the third century. The principal intention of this aqueduct has been originally to supply the great villa of Hadrian at Cento-Celle, but a branch of it does appear to have been brought into Rome. Although it is very difficult to trace it for the last two miles, this may arise from the general use of all the aqueducts near Rome as quarries, by the engineers of the Aqua Felice. In the excavations made in 1871, in the high ground near the Minerva Medica, between the Porta Maggiore and the Porta di San Lorenzo, by the

The fragment of an inscription relating to this aqueduct was found near Gabii, and is described by E. Q. Visconti in his Monumenti Gabini, Roma, 1797, 8vo. maj., p. 14.

IMP. CAESAR DIVI TRAiani
(Parthici filius Trajanus Hadrianus)
AVG. PONTIF[ex Maximus]

AQVAE DVCTVM GABINIS . . .
QVAM

The second line appears to be an interpolation of the editor, but this is not material. The aqueduct begun by Nerva was not finished till the time of Hadrian. The aqueduct of Gregory XIII. and Sixtus V. (Felice) (A. D. 1572-1590) receives the water of this aqueduct, but at Colonna other springs are collected and added to it; this was the work of Fontana.

side of that portion of the Marcian arcade that has been mentioned as found there, was also part of another arcade of an aqueduct of the third century, which may have belonged to this, and it was in that neighbourhood that the inscription belonging to the aqueduct of Severus was found.

About a mile nearer to Rome, at the Torre Pignattara, or Mausoleum of S. Helena, there is a branch from the Marrana, passing under the Aqua Marcia, apparently to convey water to an imperial villa. The construction of the arcade of this branch to the south of the road is not of the same period as that of the other arcade on the other side to the north. It is usual for modern topographers, following Fabretti, to consider this branch a continuation of the Aqua Alexandrina; but as the water from the Marrana, which is at a considerably lower level than the Aqua Marcia, runs down the gentle incline of this arcade towards the road and the Mausoleum of S. Helena called Torre Pignattara, this is impossible. The construction is chiefly of the fourth century. The Mausoleum of S. Helena is on lower ground than this part of the Marrana.

Constantine is said to have built a villa for his mother near her tomb; but there are no remains of an imperial villa nearer than those called the Cento Celle, a mile further along the road, or the one called "Torre de' Schiavi," i.e. Tower of the Slaves, about a mile across country, on another road, but on the same level. A milestone for the third mile, found opposite this mausoleum, with an inscription of the time of Maxentius, has been published by Ciampini. This indicates that some works were going on there at the end of the third century, and the arcade may be of that riod.

A large a very remarkable reservoir of the time of Trajan or Hadrian remains a little to the west of the mausoleum, and on rather higher ground. This was probably to receive the water for a branch to the imperial villa, afterwards taken possession of by the Gordiani, who built at that place their great family mausoleum, on which a tall medieval tower was afterwards erected; of this, very picturesque ruins remain, under the title of Torre de' Schiavi.

The Torre Pignattara is so called from the earthenware pots (pignatte) of which the vault was built. Other remains of buildings of importance have been found near the Mausoleum of S. Helena, and there is some reason to believe that another imperial villa

was situated there during the first three centuries.

Some say the popular name is Torre de Scavi, or of the excavations from some great works of excavation made there in the twelfth century.

There are at the same place other large reservoirs of the time of the Gordiani, shewing that the great imperial villa was still supplied with water from the Marcian aqueduct in the third century.

No water under the name of Hadrian is mentioned in the Regionary Catalogue of the fourth century, it is therefore evident that this great aqueduct was not called then after that emperor, although we are told in his life by Spartianus, that many were made in his time, and were at first called after him (as we have said '). At the first reservoir, the starting-point, there was an inscription of Hadrian, and the other reservoirs belonging to it are also constructions of the same period. It may be that this water did not come into Rome at all, but that the aqueduct was made to supply the great villa in the place now called "Cento-Celle," to which it leads in a direct line, and where it appears to terminate. If any alterations were made, these may have been done in the time of Alexander Severus, and this may now represent the so-called Aqua Alexandrina, as Fabretti thought, although he was certainly mistaken in one part of his account of it. The branch which went by the Mausoleum of S. Helena, and which apparently ran underground to the Villa of the Gordiani, was not a branch of the aqueduct to convey water into Rome, but a branch from the great aqueduct for the villa or villas, as it now does from the Marrana at a lower level. This short arcade is of the time of Constantine. The great and long one that leads to the Cento-Celle is of two periods, the earlier part of the time of Hadrian, the latter of the third century. It is quite possible that the original specus had become choked up with stalactite in the course of a century, and that it was restored to use for a time by Alexander Severus, and so called after him.

THE BRANCH OF TRAJAN ON THE AVENTINE.

It has been mentioned in the account of the Anio Novus (IX.) that, after the main conduit reached the great reservoir at the arch of Dolabella, it was divided into three branches, and that one of these was not completed until the time of Trajan and Hadrian. This important branch was carried over the valley between the Coelian and the Aventine on a lofty arcade, built upon the agger of Servius Tullius, and over the Aqua Appia, also passing over the Via Appia upon the arch of the Porta Capena to the Piscina Pub

i Note f, p. 88. "Aquarum ductus etiam infinitas hoc nomine (Hadriani)

nuncupavit." (Spartianus in Hadriano, c. 20.)

lica. It then ran along the edge of the cliff to the north of S. Balbina, and crossed again the valley between the Pseudo-Aventine and the Aventine itself, a little further to the west, by the side of the road which goes down the hill towards S. Prisca. In the vineyard of S. Prisca a portion of the specus remains perfect, at a very high level. From thence it was carried across the hill to the cliff above the Tiber, where the monastery and garden of S. Sabina are now placed. These are on the site of a palace of the time of the early Empire. Some extensive and important excavations were made there in 1855-57, by the Dominican monks of S. Sabina, and among the discoveries then made were an extensive series of conduits, with a piscina and a nymphæum of the same period, of the end of the first and the beginning of the second century of the Christian era. A cascade specus served to conduct the surplus water down to the more ancient cave reservoir at the mouth of the Aqua Appia, at the Salaria. An account of these excavations was drawn up by M. Descemet', and published in the Memoirs of the Institute of France, with an excellent plan and section. Several brick-stamps, of which the words are given in that work, with the names of the consuls, and some terra cotta water-pipes, with the name of Trajan, were also found here. Others were discovered on the Aventine and near the same spot by Fabretti, who was puzzled by them, because they did not agree with his theories about the aqueducts. Donatus also mentions some of the same facts as known in his time. Some of the bricks were made at the kiln (figlina) of Annius Verus, said to have been on the Aventine, near the Salaria; and, if this is correct, that was the spot where they were found. Others have the stamp of Trajan himself. Another is the work of an Arabian servant of Q. Servilius Pudens, A.D. 139, when the Emperor Antoninus Pius and C. Bruttius Præsens were consuls. A piece of leaden pipe, with an inscription upon it, AQVA TRAIANA, was also found on the Aventine.

It is immediately opposite to the Palatine, and there is a remarkably fine view from the portion of the specus that remains, the vault of which has been

removed, and it is used as a terrace.

Mémoire sur les fouilles exécutées à Santa Sabina. Paris, Imprimerie Impériale, 1868, 4to.