lines over heights and dales, with the crests of the hills lowered by deep cuttings, or they were conducted across valleys upon high viaducts, and along morasses upon long embankments when necessary, as may still be seen. For these great works are never wholly effaced, but bear continual witness to the grandeur of their construction. In the time of the Emperors the principal Viæ were made regular post-roads, by establishing stations at every stage of from four to six miles, each of which posts was provided with forty horses; and by the help of these it was easy to travel a hundred miles in the day. Gibbon relates that in the time of Theodosius a journey was made by a magistrate from Antioch to Constantinople, 665 English miles, in about five days and a-half. And in estimating the distance traversable by these roads within the Empire's boundaries, he calculates that from the Wall of Antoninus in Britain to Rome, and from Rome to Jerusalem, the great chain of communication was drawn out from north-west to south-east to the length of four thousand and eighty Roman miles. To make the system perfect the milestone was added, a Cippus or Milliarium being erected at every mile, with the number upon it; this was due to Caius Gracchus, B.C. 123. Raised causeways, margines or crepidines, on each side of the main street, provided for the safety and comfort of foot-passengers; and lastly, mounting-stones were fixed at the roadside for the convenience of horsemen to regain their seats. THE AQUEDUCTS. WE have now to describe the system of Aqueducts con nected with the City. While it is true that no remains of antiquity that have survived to modern times are more worthy of admiration than these monuments of Roman skill and boldness, it is also true that it is impossible to understand the material history of Rome without studying them. They form a constituent portion not only of the useful and architectural features of the place, but also of its defensive works: for on its eastern side they form a long line of rampart in connection with the Wall of Aurelian, and they have borne an important part in various sieges of the city. It has required a close and patient study to unravel the great network of conduits, which partly above and partly underground carried water sufficient to supply the Thermæ, Naumachiæ, and countless fountains. But this has been done, and we are able to give an account of all the known aqueducts formerly entering the walls, with the exception, perhaps, of a branch from one of them to the Thermæ of Diocletian. Most of them have been traced from the source downwards, and a chart on a large scale, the result of actual investigation, shews where each ran as far as to the walls of the city, while the most important ramifications within the walls are shewn on separate diagrams. The spot also where • The discovery of a respiratory, or ventilating-shaft, over the filledup foss of S. Tullius, and which stands close to the angle of Diocletian's baths, indicates most probably the aqueduct introduced from an older one; and the immense bank of earth mentioned in Cap. V. as burying the lofty wall of that king was, no doubt, thrown up at the time when the soil was excavated for the substructions of those thermæ. most of the older water-courses finally discharged themselves has been discovered. Fortunately we have a trustworthy guide to the history of the Aqueducts in Sextus Julius Frontinus, who was Governor of Britain under Vespasian, and was appointed Curator Aquarum, Superintendent of Aqueducts, A.D. 97. He tells us not only what was effected during his own administration, but also gives an historical account of the advances made from time to time in the means of supplying water to the city, so as to keep pace with the growing wealth and population. At the time of his death these works had probably reached perfection, and were justly the admiration and surprise of all travellers. He states in his fourth chapter that for 441 years after the building of the city, i.e. till B.C. 312, the people were content with the water which they drew from the Tiber or from wells and springs. At the time of writing his treatise, he says there now flow into the city : In describing these nine aqueducts in order, he gives par ticulars as to the source of water to each, the quantity, and the distribution. In later times seven others were successively added, namely, X. Aqua Sabatina, now XIII. Aqua Severiana. Paola. XIV. ΧΙ. - Trajana, or Ha- XV. driana. XVI. Antoniniana. Alexandrina. - Algentiana. These are all that are known belonging to the times called classical. In addition, there was one added, or rather restored to use from the old sources, in the twelfth century, one in the sixteenth, and one in the third quarter of the nineteenth. Procopius gives the number existing in his time as fourteen. The channel of an aqueduct was called Specus, and was built of stone carefully cemented: after the time of Claudius the specus of concrete was faced with brickwork. The floor was laid with the kind of concrete called Opus Signinum, modernly Coccio Pesto, made of broken pottery and Pozzolana sand mixed with fresh lime, forming a coating impervious to water. The specus was closed in above to exclude impurities, and also the sun's heat, so that the water might come down as cool as possible: this covering was in some cases an angular roof coming to a ridge at the top, in some it was square, in some arched. The two earliest, Aqua Appia and Anio Vetus, were ridge-roofed; the third, Aqua Marcia, is square-headed; the first that was arched is the Aqua Virgo, of the time of Augustus; and all three forms were repeated in subsequent structures. It is observable that no two aqueducts shew the same section across; for it was necessary to distinguish them, so that the workmen, who were called Aquarii, might always know to which of them each channel belonged at the points where they cross each other, and thus, in the process of repairing or cleansing an obstructed specus, might without error follow up the course required. The channels varied also very much in dimensions as well as in form. The Aqua Marcia may be taken as a typical representative of size, being five feet high by two and a-half in breadth, and the thickness of the wall on each side is one foot. The Claudia and the Anio Novus were considerably larger; the area of the channel of the Virgo was just half that of the Claudia. At the source of each aqueduct a filtering-pool, Piscina i Limosa, or Limaria, was constructed to catch the impurities held in suspension by the water, before it was led away into the specus. These were repeated at intervals, and were usually connected with the structure called Castellum Aquæ, or reservoir. The force of the water running in a strong current from such great distances required to be broken frequently, and this was effected by turning the course at a sharp angle, and then allowing it to resume its former direction by another angle. It is observable also that the base of the channel is often broken by inequalities or dips, as if purposely introduced to agitate the fluid in its course, and thus to make it combine with a larger quantity of atmospheric air; and these inequalities would tend to check the passage of heavy earthy matter held in the water. In addition, there were ventilating-shafts at proper intervals, which were used also as wells to let down buckets for drawing water, and on the sides of these shafts steps were cut for the workmen to descend into the specus and remove obstructions. In directing how the levels should be taken for carrying water through the valleys, Vitruvius says that there should be standing or upright pipes, Columnaria, as respirators, to let off the confined air, and thus reduce pressure. The sharp angles spoken of just above were made useful for carrying the later and higher aqueducts over the older courses. This arrangement is admirably seen at the building called Torre Fiscale, three miles out of Rome on the east side, and also at the Porta Maggiore. At the former, five aqueducts are carried through the same tower, three in one arcade, and two in another, at right angles to them; and the Aqua Felice runs at the foot of the tower. The same six pass at the gateway, Porta Maggiore, the Claudia and Anio Novus over it, and the Marcia, Tepula, and Julia on the northern side of it, and the Felice also over it; the three continue onwards H |