CHAPTER IV.

THE WATERS.

Land artificially won from the Waters: _a_, Exclusion of the Sea by Diking; _b_, Draining of Lakes and Marshes; _c_, Geographical Influence of such Operations--Lowering of Lakes--Mountain Lakes-- Climatic Effects of Draining Lakes and Marshes.

Geographical and Climatic Effects of Aqueducts, Reservoirs, and Canals--Surface and Underdraining, and their Climatic and Geographical Effects--Irrigation and its Climatic and Geographical Effects.

Inundations and Torrents: _a_, River Embankments; _b_, Floods of the Ardèche; _c_, Crushing Force of Torrents; _d_, Inundations of 1856 in France; _e_, Remedies against Inundations--Consequences if the Nile had been confined by Lateral Dikes.

Improvements in the Val di Chiana--Improvements in the Tuscan Maremme--Obstruction of River Mouths--Subterranean Waters-- Artesian Wells--Artificial Springs--Economizing Precipitation, 330