The cement used in building the work is as hard as the stones themselves, and, such is the tenacity of that which coated the water channel, that where flakes of it of 100 feet in length have fallen from the wall, they lie unbroken. The conduit is 6 feet high within, and 4 feet wide, "arched to a point" says Stuart. At Ariana, about four miles from Tunis, other remains of this aqueduct are visible. When mountains were tunnelled in its course, at every 60 yards, vertical openings were driven through from the surface of the channel way to the upper air. These openings or ventilators are 4 feet in diameter, walled with hewn stone, and carried up about 4 feet above the surface.

The Emperor Charles V., caused a drawing to be made of various portions of this noble work the celebrated Titian arranging the designs, to serve as a model for some

tapestry to be executed for the Austrian Court. * Frontinus, p. 206. t Stuart, Die. Archi., art. Aqued.

PRELIMINARY ESSAY. 29

Of the Roman works in Gaul, we borrow our account from Stuart :

" The aqueduct at Nismes, is probably one of the earliest that was constructed by the Romans out of Italy. Its origin is attributed to Agrippa, who was invested by Augustus with the government of this city, which had become a Roman colony. Flattered by the attentions of the citizens, Agrippa made their city his place of residence, and he adorned it with new city walls and magnificent baths. Those who suppose that the object of the aqueduct was to conduct water to the amphitheatre only, instead of being appropriated to the domestic uses of the inhabitants, have not regarded with attention the peculiarities of its construction. The simplicity and unornamented style of its architecture, perfect, however, in its proportions, and just in every point of its design, marks the very character of these works of Agrippa.