Hydraulic Engineering in l~rance.--M, de Lesseps has called the attention of the French Academy to the distribution of the waters flowing from the natural declivities of the French territory, and to the improvement of internal navigation. In view of the wealth.of its hydrographic basins, of their importance, and of the facility of inter-communication, France is the most favored country of Europe. Far from profiting by this happy position, and notwithstanding the abundance of rivers, the meadows are of a limited extent, large tracts are exposed to droughts which oppose the improvement of their culture, and immense amounts of valuable material arc continually wasted. M. Herve Mangon estimates that the volume of mud annually carried off by the Durance, bears to the sea more than 14,000 tons of nitrogen, in the state of combination which is best fitted for the nourishment of cultivated plants. At the same time, agriculturists buy from foreign countries, at great sacrifice, other nitrogenous matters, and the importation of guano, which scarcely furnishes so large a quantity of nitrogen to French agriculture, costs it thirty million francs per annum. The same mud contains nearly 100,000 tons of carbon, or as much as would be furnished by a forest of 50,000 hectares.
M. Cotard proposes to store all the summit-waters, in the basin of the Garonne and the Adour, and distribute them in such manner as to feed the channels of internal navigation, facilitate the transport of industrial products to good markets, and avoid the accumulation of stagnant waters in unhealthy marshes. The French Agricultural Society endorses his project with strong recommendations.
Hubert Delisle sets forth all the benefits of the water-courses in transporting bulky and cheap products, regarding it as an important object to put all parts of the territory into easy communication. He would develop five great lines: 1, the Eastern line, putting Havre and the northern ports in communication with Alsace and Switzerland by the Seine, the enlargement of the sluices of the canal from the Marne to the Rhine, and needful improvements along that canal. 2, the line of the grand-girdle canal, connecting the rich basins of the Oise, the Aisne, the Marne, the Aude, the upper Seine, and the Β₯onne, thus establishing relations, on one hand with the navigable waters of the north, on the other with the channe!s of Burgundy and Orleans. 3, the Western line, to put Nantes and the departments watered by the Loire, the Santhe, the Maycnne, the Cher and the Vienne, in communication with Paris, the north, the east and the