Nor was it for the uses of the capital alone that aqueducts were constructed. The A. of Trajan, at Civita, Vecchia, which conveys the water a distance of 23 m., and that in the vicinity of Marzana, near Verona, with others that might be mentioned, still attest the existence of aqueducts in the smaller towns of Italy in Roman times. Even during the unpromising period which succeeded, the habit of their construction was not aban doned, that of Spoleto having been built by the Lombard duke Theodolapius in 604. The extraordinary A. by which the fountain at Siena is supplied, is said to have occu pied two centuries in building; and the modern A. of Leghorn, which is not unworthy of the Roman models after which it was desigied, is surpassed in magnificence by that of Pisa, with its thousand arches. In the more distant provinces which fell under the Roman power, aqueducts were likewise constructed—at Nicomedia, Ephesus, Smyrna, Alexandria. Syracuse, and in many of the towns in Gaul and in Spain. At Merida there there are the remains of two aqueducts, of one of which there are 37 piers still standing. with three tiers of arches. But the most magnificent structure of this class in Spain, is the A. of Segovia, in Old Castile, for which Spanish writers claim an antiquity beyond that of the Roman dominion; but which, there is reason to believe, belongs to the time of Trajan. At Evora, in Portugal, there is likewise an A. in good preservation, with a castellunt or reservoir at its termination iu the city, consisting of two stories, the lower one being decorated with pillars. But of all the provincial aqueducts, that at Nismes, in Provence, is at once the most remarkable and the best preserved. The following de scription of it, which we transcribe from Mr. Murray's excellent band-book for France, will convey to the reader a very vivid conception not only of this A. in particular, but of the very interesting class of works to which it belongs. " It consists of three rows of arches, raised one above the other, each smaller than the one below it; the lowest of 6 arches, the center tier of 11, and the uppermost of 35; the whole in a simple if not a stern style of architecture, destitute of ornament. It is by its magnitude, and the skillful fitting of its enormous blocks, that it makes an impression on the mind. It is the more striking from the utter solitude in which it stands—a rocky valley, partly covered with brushwood and greensward, with scarce a human habitation in sight, only a few goats browsing. After the lapse of 13 c., this colossal monument still spans the valley, join ing hill to hill, in a nearly perfect state, only the upper part, at the northern extremity. being broken away. The highest range of arches carries a small canal, about ft. high
and 4 ft. wide, just large enough for P. man to creep through, still retaining a thick lin ing of Roman cement. It is covered with stone slabs, along which it is possible to walk from one end to the other, and to overlook the valley of the Gardon. The height of the Pont du Gard is 183 ft., and the length of the highest arcade 873 feet. Its use was to convey to the town of Nismes the water of two springs, 25 m. distant. . . . The conveyance of this small stream was the sole object and use of this gigantic structure, an end which would now be attained by a few iron water-pipes." Neither the date nor the builder of the Pout du Gard is known with certainty, but it is ascribed to Agrippa, the nephew of Augustus; a conjecture which is rendered probable by the fact of his having restored the Appian, Marcian, and Anienian, and constructed the Julian A. at Rome. The importance which the Romans attached to their aqueducts may be gathered from the fact, that special officers, invested with considerable aPthority, and, like all the higher officials, attended by lictors and public slaves, were appointed for their superin tendence. Under the orders of these "guardians of the waters," we are told that, in the time of Nervy and Trajan, about 700 architects and others were employed in attending to the A. These officials were divided into various classes, and known by different names, according as their duties related to the care of the course of the A. the cas tella or reservoirs at its termini, the pavement of the channel, the cement with which it was covered, and the like.
The construction of aqueducts in recent times is comparatively rare, water being now generally conveyed in pipes; but two instances are worthy of notice—the Lisbon, A., and the Croton at New York. The former, completed in 1738, is about 3 leagues in length; near the city, it is carried over a deep valley for a length of 2400 ft. by a number of bold arches, the largest of which has a height of 250 ft., and a span of 115. The Croton A., which conveys the waters of the Croton river for a distance of 38 m. to the city of New York, is one of the greatest undertakings of modern times. It was com menced in 1837, and finished in 1842, and is calculated to discharge upwards of 60,000, 000 gallons in 24 hours. As the magnificence of aqueducts depends upon the height and number of arches requisite to carry them across valleys, it may give some idea of that under consideration when it is stated that Harlem river is crossed by 15 arches, 7 of which are of 50 ft. span, and 8 of SO ft., the greatest height being 150 ft. from the foun dation to the top of the mason-work.