Page:Popular Science Monthly Volume 11.djvu/37

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design among the existing remains of works of this class carried out by the ancient Romans." It is constructed entirely of freestone, to the covering of the upper row of arches. The stones were laid without cement, and each was raised by the lewis, the holes in which it was inserted being still visible exactly over the centre of gravity in every stone. Still more remarkable for height is one of the bridges of the aqueduct of Antioch, also built by the Romans. It is 700 feet long and 200 feet high. The lower part consists of a solid wall pierced by two arches, in the centre—one upon the ground, the other directly above. Along the top is a row of narrow arches. The design and workmanship of this structure are very rude. But in later times arcades of even greater height have been built. The arcade Delle Torri, near Spoleto, built in the seventh or eighth century a.d., is about 300 feet high and over 700 long. It consists of ten arches between lofty columns, and is remarkable as an early example of the pointed arch, as well as for lightness of design. The arcade of the Roquefavour Aqueduct across the river Arc is 262 feet high, and 1,287 feet long. This aqueduct supplies the city of Marseilles with water from the river Durance, 51 miles distant. It was constructed between 1839 and 1847, and has eight and a half miles of tunnels passing through three chains of limestone mountains. But the most imposing arcade in the world, as regards the combined effect of height and length, is that of Maintenon. It is about five-sixths of a mile long, and over 200 feet high. Louis XIV. built it for an aqueduct he projected to convey the water of the Eure from Pont Gouin to Versailles, a distance of about 33 miles. This great enterprise was abandoned in 1688, after an expenditure of four years and 22,000,000 francs. The design contemplated one arcade over three miles long, which in its highest part was to have been formed of three tiers of arches.

At the time that it was built, the Anio Novus, probably of all aqueducts in the world, drew its water from the most distant source. True, the conduit of the Aqua Marcia, one of the most important of the aqueducts of Rome, was longer, but its source was only 39 miles from the city, while that of the Anio was 42; the conduit of the one was 61 miles and 710 paces long, of the other 58 miles and 700 paces. There are at Carthage the remains of an aqueduct which is said to have been over 50 miles long, but it is impossible to tell whether it was built by the Carthaginians proper, or by the Romans who, long after the destruction of the old city, founded a new one on its ruins. The accompanying cut represents the remains, near Undena, of one of the arcades of this aqueduct. It comprised 1,000 arches, many of which were over 100 feet high. The ancient Peruvians are said to have built the most remarkable aqueducts in the world for length. Garcilasso speaks of one that was 360 miles long, and another 450, but these were for irrigating purposes, and they wound around the mountains and followed the surface of the valleys instead of crossing