Although an adventitious addition, it is clearly Roman work, probably of a much later age.

The length of this aqueduct, as far as discovered, is about six French leagues, or 15 miles, in a direction resembling a horse-shoe, and derives its water from the spring of Eure, and Airau, near the village of Uzes. The Pont du Garde is in the middle of its course the greater part of the ancient line can now be traced, and much of what ;

remains in a fine state of preservation. is The observation made with regard to the parts of the aqueducts of Rome which were under ground, being in the best state of repair, applies with still greater force to the aqueduct at Nismes, the subterranean parts being even now in perfect preservation. The line was carried along the sides of the

30 PRELIMINARY ESSAY.

hills, which were occasionally perforated to shorten the distance, and, where necessary, .the lesser valleys were crossed by the erection of small bridges, or arcades, preserving the level of the aqueducts. The greater portion of the excavated part has been cut through the stone strata of which the hills are composed, in some places at a distance of about 13 feet beneath the surface.

The Pont du Garde, is that part of the aqueduct of Nismes which traverses the deep valley in which runs the Garden or Garde, between the mountains near Vers and St. Bennet.

This considered even alone, is one of the grandest erections made by the part, Romans in Gaul. The first row of arcades, beneath which runs the Gardon, is composed of six arches ; the second row has eleven arches, and the third range has thirtyfire. All these arches are semi-circular, springing from piers, more or less high ; it was