There can be no doubt that but for the efforts of the Venetian engineers the lagoons of the Lido, Malamocco, and Chioggia would long ago have been converted into dry land. Venice has at all times been alive to the necessity of preserving its precious inland sea. The Venetian engineers were not content with turning aside the torrents which formerly poured their waters into the lagoons; they have also, by means of canals, moved the mouths of the Sile and Piave to the east, thus securing the ports of the Lido from the dreaded alluvium of the rivers. They even conceived the gigantic project of a huge encircling canal for the interception of all the Alpine torrents between the Brenta and Isonzo. This project, however, has never been carried out. The débris carried southward by the coast current has silted up the port of the Lido, which was abandoned towards the close of the fifteenth century, when a new military port was constructed eight miles farther south, at the canal of Malamocco, and it is now protected by a pier extending 7,200 feet into the sea.

The torrents which descend from the slopes of the Apennines to the south of the delta of the Adige and Po are as erratic in their course as those of Venetia. The Trebbia, the Taro, and other rivers irrigating the districts of Piacenza and Parma only cross a narrow plain between the mountains and the Po, and do not much modify the topography of the country. But this cannot be said of the rivers flowing through the vast plains of Modena, Bologna, Ferrara, and Imola. They are constantly changing their beds, and the remains of embankments met with all over the country prove that all efforts to confine them permanently have proved abortive. Modena itself was once destroyed by the floods of the Secchia. The Tanaro, the Reno, and other rivers flowing towards the north-west, either into the canal encircling the lagoons of Comacchio or direct into the sea, all have a history attached to them; they are blessed for their fertilising alluvium, cursed on account of their destructive floods. One of them, probably the Fiumicino, is the famous Rubicon which bounded the Italy of the Romans, and which was crossed by Cæsar when he pronounced the fatal words, “Alea jacta est.”

The Reno is the most erratic, the most dangerous of all these Apennine rivers. The bed of débris deposited by it in the plain measures 20 miles across from east to west. Its volume varies between 35 and 49,500 cubic feet a second, according to the season, and its bed is in places no less than 30 feet above the adjoining country. The destruction of the forests has augmented the danger of its inundations. The engineers, puzzled by its irregular floods, have proposed the most {209} opposite plans for subduing this terrible scourge. The river has been turned into the Po; then eastward, direct into the sea. Recently it has been proposed to divert it to the lagoons of Comacchio. But all these diversions are attended with disadvantages, and whilst the inhabitants of one district congratulate themselves upon having got rid of so troublesome a neighbour, those of another complain of its inundations, see their fisheries destroyed, and their navigation interfered with.

[Μ]

Fig. 68.—COLONIES OF THE ROMAN VETERANS.

Scale 1 : 356,000.

Lombardini, the famous hydraulic engineer, has shown how we may discover the places to which the soil of the lowlands of Emilia has been conveyed by the torrents, and trace the ancient shores of the lagoon of Padua, now converted into dry land. A traveller following the Emilian causeway from Cesena to Bologna can hardly help noticing the quadrangular fields on his right, all of them of the same size. Looked at from the spurs of the Apennines, the plain resembles a huge draught-board, the squares of which are covered alternately with verdure and ripening crops. We learn from the topographical maps that these fields are exactly of the same size, and there can be no doubt that we have here before us the fields which, according to Livy, were taken from the Gauls and distributed amongst Roman military settlers. A sinuous line marks, in the direction of the Po, the shore of an ancient lake. The rectangular fields, laid out by the cadastral surveyors of ancient Rome, cease there, and we find ourselves again amidst the usual labyrinth of ditches and tortuous roads. This lake has been filled up long ago by the débris brought down by the torrents. {210}

The Po, proportionately to the area it drains and its length, has undergone fewer changes than either the Piave or the Reno, but looking to the populous cities which line its banks, and to the fertility of its fields, the least of these is of some importance.

The torrent fed by the snows of Monte Viso is usually looked upon as the head stream of Father Po, as the ancient Romans called the river; but the Mastra, Varaita, and Clusone are quite equal to it in volume, and feed as many canals of irrigation. Indeed, these canals would quickly drain the Po if it were not for a bountiful supply of snow-water brought down by the Dora Riparia, the Stura, the Orca, and the Dora Baltea from the glaciers of the Alps. Lower down, the Po receives the Sesia from the north, and the Tanaro, which is fed by streams rising in the Apennines and the Alps. Then comes the Ticino, by far the most important tributary of the Po, “without which,” as the river fishermen say, “il Po non sarebbe Po.”