_The Crapponne Canal._—The authority to construct this canal was conceded to Adam de Crapponne, an eminent engineer in the year 1554. It takes its water through sluices, from the river Durance, near St. Estève-Ianson, at an altitude of 492 feet above sea level. There the river varies from 600 to 6500 feet in width, and the bed consists of a succession of sand and gravel banks, and alluvial deposits, intersected by numerous branches, which shift at every flood. Such a state of things cannot be considered as constituting the bed of the river, in the ordinary acceptation of the term, and to have constructed a permanent and fixed barrage across the river, to lead the water through the sluices, would not only have been a costly work at that time, but also one of considerable difficulty. Crapponne constructed, therefore, what are termed “barrages volants” across the river. These are formed where the depth of the water is about two feet, by stakes with fascines, and filled in with stones. In the deeper parts of the river, which may be sometimes 12 to 15 feet, “chevalets” are driven in place of stakes. These consist generally of trunks of trees cut near the point of the bifurcation of the principal branches, and which are placed closer together in proportion to the depth. The “chevalets” are bound by cross-pieces and supported by fascines. These “barrages volants” are always placed obliquely to the current of the river, for the purpose of causing the fascines to press against the stones or the “chevalets.” Such “barrages volants” need continual repair, but their cost is comparatively trifling. It is mostly a question of labour, as the material employed is cheap. The average cost of maintenance of the barrage for the Crapponne canal is about 500_l._ per annum. This system, adopted by Crapponne more than 300 years ago, has never been changed, and has been found by experience to answer its purpose of diverting the Durance waters through the sluices into the canal in all seasons, and the same system is adopted for some other irrigation canals. The Crapponne Canal, is the main canal from the river Durance to Lamanon, and is 14¼ miles in length. At Lamanon the canal has two main branches, one flowing south towards Salon and St Chanas, and the other to the west towards Arles. The total length of the canal is about 77 miles, not comprising the whole development of the branch to Arles, which is a special property, independent of the original canal. The quantity of water supplied by the canal, is as follows:-The main canal is 26 feet wide, and 6·5 feet deep; the mean velocity is 5 feet per second. The branch to Salon is 10 feet wide, and 6·5 feet deep; the mean velocity is 6·5 feet per second. The branch to Arles is 16·5 feet wide, and 3·28 feet deep; the mean velocity is 5·3 feet per second. The branch to Istres is 6·6 feet wide, and 3·3 feet deep; the mean velocity is 6·6 feet per second.