He had no knowledge of the reservoir discovered by Delorme, to which it is probable these pipes belonged, and in which they were used for distributing the water to the buildings and gardens of the palace of the Emperor Claudius. The aqueduct of Metz is another of the great works of the Romans, though of what precise date seems uncertain possibly of the period when the legions of Caesar held possession of Gaul. The water which it conducted into the town was taken from the valley above Gorze distant about 23 miles now called Les Bouillons. The construction of the work was essentially similar to those already described. It was in its whole length a close conduit of masonry, and carried over valleys by lofty arcades, no recourse being had to syphons or leaden pipes.

40 PRELIMINARY ESSAY.

Spain, too, yet preserves some splendid aqueducts of Roman origin. That at Segovia the most remarkable has an arcade of 159 arches, 94 feet high, and extending across a valley 700 yards in width. This work is ascribed to Trajan.*

Upon a level at its origin with the rivulet it receives, and supported at first by a single range of arches not more than three feet high, it proceeds to the summit of a hill at the other extremity of the city, and gradually increases its height in proportion

to the declivity of the ground. In its highest part a bridge has been thrown across an

abyss. It has two branches which form an obtuse angle with the city. At the commencement of the angle it becomes a grand object. Its two rows of arcades rise majestically above each other, and the spectator is surprised at its gigantic height, and the It has stood 1600 years. lightness of its piers. Nor can we pass by the extensive works at Grenada, though of comparatively modern date, for supplying, with Arabian magnificence, the waters of the various baths, fountains, and apartments of the famed Alhambra.