Gauls. It is composed of three ranges of arches one above another. The first range, under which the Gardon flows, is formed by 6 arches ; the second by 11, and the third by 35, all of which are semicircular ; supported upon piers of greater or less height. 20 The channel in which the water flows is upon the top of the third range of arches, and is 160 feet above the water of the river. The whole length of this bridge is about 900 feet. The bridge of Gard having been broken down at the two extremities, at a period very remote and uncertain, it is thought that this destruction may be attributed to the Bar- barians who invaded the country of Nismes a short time after their first invasion, which is fixed at the commencement of the fifth century, about the year 406, and it is supposed that by this means they would deprive the inhabitants of Nismes of the water furnished by the Aqueduct, and force them to yield. But by this supposition, which is very pro- bable, the water had been running in this Aqueduct for more than four centuries ; and this structure which has been out of use during fourteen hundred years, is still in such a state of preservation that it could be restored without a very great expenditure of money. The Ancient Aqueducts of Lyons. Nothing gives a better idea of the splendour of the city of Lyons under the reign of the first Roman Emperors, than the remains of the ancient monuments. We see there at the present day, remains of temples, of palaces, of amphi- theatres, of basins for mock sea fights, of baths and of many Aqueducts, of which three were constructed under the reigns of Augustus, of Tiberius and of Claudius, for conducting water to that part of the ancient city situated upon the mountain. 21 The first and the most ancient of these Aqueducts, con- structed by Mark Anthony, brought the waters from Mount- d' Or, by means of two branches which embraced that group of mountains. The water furnished by the first Aqueduct having been found insufficient, they constructed a second one to bring the water of the Loire. The third Aqueduct was built by the Emperor Claudius to furnish water to the palace of the emperors situated upon an elevated mountain. The Aqueducts built at this era are all of the same construction ; that is to say, from the plan and construction adopted by the Romans. A fourth Aqueduct was also constructed for this city, but there is some doubt whether it was built by the Romans. Aqueduct of Mount Pila. This Aqueduct was built by Claudius, who was born at Lyons, to conduct water to the emperor's palace, situated on the highest part of the city. The sources which supplied it, were in the neighbourhood of Mount Pila, and they were brought into the main Aqueduct by branch aqueducts. The main Aqueduct was forty miles in length ; and adding the branches, the length of the Aqueduct was forty-five miles. There were 13 bridges of stone to support the Aqueduct across valleys or over rivers, two of which were not built up to the plane of the Aqueduct, but were crossed by leaden 6 22 pipes which descended on one side of the valley and, crossing the bridge, ascended on the opposite side. In another instance the pipes descended and crossed upon a wall of masonry and reached the opposite side of the valley. One instance, where pipes were used, will give an idea of their general form : the bridge was about 40 feet high and the perpendicular height of the Aqueduct above it was 140 feet. Nine leaden pipes of about 8 inches interior diameter and one inch thick were laid upon the inclined planes and across the level part of the bridge ; thus communicating with the opposite crests of the valley. These bridges which were constructed for the support of pipes, were wider in the bottom of the valley and also half way up the inclined plane, than they were for the remainder of the distance ; and this form has suggested the idea that the pipes of 8 inches diameter, when they reached half way down the plane, separated, each one into two of 6 inches diameter which crossed the bridge, and converged into one again half way up the opposite plane. But it may be sup- posed that they continued of the same interior form through- out their length, and that this extra width was made for the purpose of giving an opportunity to fortify the pipes at the place where the pressure to which they were subjected was the greatest. Construction. They commenced the construction