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.” The Po, after its junction with the Ticino, exhibits no longer the features of a mountain torrent; the pebbles have been triturated into the finest dust, and no piled-up masses of débris are met with along its banks. If it were not for its dykes, or _argini_, it might spread itself freely over the plain. These artificial embankments rival those of the Netherlands, and date back to the most remote ages. Lucian refers to them as if they had existed from time immemorial. During the great migration of peoples they were allowed to decay, and only in the course of the ninth century were measures taken to restore them. In 1480 the great work had been achieved. Its importance may be judged from the fact that these embankments protect 3,000,000 acres of the most fertile land, yielding annually more than £8,000,000 sterling’s worth of agricultural produce. Most of the towns have been built upon artificial platforms or terraces, and up to the beginning of this century they have never been known to suffer from floods; but whether owing to the devastation of the forests or to the closing up of all breaches in the dykes, the floods rise higher now than they did of yore, and it has been found necessary to throw up embankments around Revere, Sermide, Ostiglia, Governolo, Borgoforte, and other places. [Illustration: DELTA OF THE PO]