The utmost breadth of the piers of the aqueduct of Chaponost, which carried a canal of three feet broad, by six feet high, is not more than six feet, while the breadth of the aqueduct which passed over the river Baunan, arid which has no canal, is 24 feet broad, consisting of two piers, each five feet, supporting an arch 14 feet in diameter. M. Delorme,in his account, (Seance de 1'Academie, 1759,) traced three of the

aqueducts of ancient Lugdunum to their source, in three several tracks, of many miles each. He examined their general level, and the level of each part, as they ran above and under ground, along the sides of the mountains, and sides of valleys, and over the bridges where they passed the valleys he observed the apparent care which the archi- ;

tects of these edifices took to avoid the building of works, enormous in bulk, height, and expense, by carrying the walls up into the narrower and shallower parts of the valleys. 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 ;