The aqueduct is built on a foundation of stone, the water runs in round earthen pipes about 10 inches diameter, which are cased with two stones hewn so as to fit them, and they are covered over with rough stones well cemented together, and the whole so sunk in the ground on the sides of the hills, that in many is to be seen of it." places nothing

It seems, however, to have been reserved for Rome and her great race, to exhibit what science, united with labor and wealth, could accomplish in this way for the health,

comfort, and luxury of its citizens.

Both Pliny and Vitruvius treat of Aqueducts, and their descriptions are curious, as giving the methods used in the construction of these works, among the greatest wonders of Rome, and as indicating a knowledge of some hydrodynamical laws, the discovery .of which is usual] y assigned to a much later period. Ducts of water according to Vitruvius, were of three kinds channels of masonry, leaden pipes, or tubes of fictile ware, according to the following rules when channels ;

are used they should be made as solid as possible, and the bed of the stream should have a descent not less than half a foot in 100 feet, and they should be arched over, that the sun's rays may not touch the water. When the water arrives at the city, a castellum or reservoir is built, and a triple emissary to receive the water is adjoined