Where smaller bridges would serve, and where they could carry the waters over a bridge by a rectilinear canal, they always built up bridges to that level, but where that would become too high, and yet where a bridge was necessary, they built bridges of a height sufficient to carry the water over in syphons of easy curvature. The sources of supply of the aqueduct of Mont de Pile, were from the waters of the from the rivulet of Sauon, and probably from the river Tanon, to which river Gievre, were joined those of the rivulet Langoneau after these waters were united in one ;

stream at the aqueduct bridge of the little Varizelle, they make a long detour on the sides of the mountains and hills, till they arrive at the valleys, which they must pass ; yet here they are seen trained along the sides of these valleys, until they come to situations which are not so deep or so wide. It is then that the architects built bridges

across the valleys, over which to conduct the waters, either in rectilinear canals, or in syphons had this latter precaution not been taken, the construction of such bridges ;

would have been of necessity so high as to become enormous, both in work and expense ;

yet, notwithstanding all these precautions, there were in the aqueduct which takes its sources in Mount Pile, and determines at the gates St. Irenaeus, nine bridges carrying

aqueducts, and three calculated to carry syphons. The ninth is in a very deep and wide bottom, on the heights of Soncieu. The aqueduct, when it arrives at this bottom, is terminated with a reservoir at the south edge of the valley of the river Garon. The mode by which the water passed this profound chasm, was by causing it to flow from a reservoir on the one side, in leaden pipes^ bedded in the sides of the valley along part of the descent it then flowed in continued ;