Among the Alpine rivers which flow into the Adriatic must be 'mentioned the Adige, which, as compared with the Po, is inferior in_ the length of its course by only about a third, but is also four-fifths smaller in the amplitude of its hydrographie basin and still less in its vol.' ume of water.
In the peninsular portion and in the islands of Italy,, the not extensive area and the special distribution of the mountains do not permit the formation of rivers; those on the Adriatic coast of the peninsula, where are found principal groups of the Apennines, are the small est. Here, on account of their short and pre cipitous course, the rivers are more like tor rents, except the Reno, which traverses the Romagna plain for a long stretch, and some that rise behind the crest of the coast chain in its ponds and recesses, as the Sangro, the Pescara, etc. In the Ionian Sea also similar causes, and, in addition the prolonged drought in summer, withdraw every value also from the larger rivers, such as the Busento, the Bradano, etc. But to the west of the Adriatic chain of the Apennines there is more diversity and less uni formity in their knots and sinuosities, for being more numerous they can form valleys in direc tions more or less oblique to the coast line, uniting longitudinal tracts of valley to trans verse tracts, and hence they can develop larger rivers with more extensive basins, as the Tiber, the Arno, the Volturno, the Liri-Garigliano, etc.
The Tiber, the river of universal historic fame, is the largest river of peninsular Italy. Its length is almost equal to that of the Adige, but its hydrographic basin is more than one fourth larger. Its sources (Monte Fumajolo) are about 149 miles distant from those of its most southern affluents, the Aniene and 'the Teverone (Monte Viglo5 in a direct line from north, northwest to south, southeast. It re ceives the waters of almost the entire Tyrrhenian water-shed from the greater Apen nine groups. For that reason, especially from autumn to spring, it is liable to frequent floods, according as the downfall of and the melting of the snows occur in one or other or all parts of its vast basin. The country, and chiefly the city of Rome, suffered greatly from these floods until the recent works of systemization in the city, which formerly experienced every year, and even several times a year, the invasion of the river which over flowed the lower wards to a depth of 10 or 12 feet. The Tiber also continues by means of de posits to extend its estuary. From the time of Christ up to our day it has added a stretch of beach more than two and one-half miles wide.
The Arno, the Tuscan river, so celebrated in the history of civilization and so dear to vo taries of the arts, has a course only three-fifths as long as that of the Tiber, and hardly half the extent of its basin. Its principal valleys may be distinguished by natural diversities very marked in four regions, i.e., in the Casentina, or Casentine Val d'Arno, wider and less impetu ous up to its junction with the Tuscan Chiana; the Upper Val d'Arno, shut in between the oppo site chains of the Pratomagno and the Chianti; and the lower Val d'Arno, from its confluence with the Sieve until it reaches the sea, the most flourishing portion of Tuscany. But even in this last region it recalls the type of torrent, as much by the coarse deposits from the bed of the river as by the tremendous force and agita tion of its waters. At Florence it may rise from a minimum flow of three cubic metres to a max imum flow of 1,000 cubic metres, and in excep tional cases to 2,000 cubic metres of water a ond. And at Pisa, on the level plain, it may fall from 2,000 cubic metres at flood to a low level of 15 cubic metres a second. Its flood tides are most often in December, and in the preced ing and subsequent months. Its lowest tide is in summer. The matter deposited at its mouth from the time of the Romans up to the present day forms a stretch of beach more than five miles wide.
Lakes.—Among the Italian lakes worthy of special mention are the beautiful Lombardy lakes, Lago di Gardi, or Benaco, 140 square miles in extent; Lago Maggiore, or Verbano; Como, or Latrio ; Lago di Lugano, or Ceresw, d'Iseo, or Sebino, di Varese, etc., which are long valleys enclosed between spurs of the Alps, shut in and protected toward the north by the• mountain, more open toward the south, and girdled by abandoned moraine hills, by ancient glaciers, with less imposing scenery, in general, than that of the Alpine lakes of Switzerland, but yet more pleasant on account of the smiling southern landscape and vegeta tion; great basins of deposits, where the abun dant waters of the rivers are purified before irrigating the luxuriant Lombard country. In other parts of Italy are scattered smaller lakes, . historically famous, as the Trasimeno or Lake of Perugia, the Lago di Bolsena, the Sabatino or Bracciano Lake, of Vico, of Albano, of Nemi, not far from Rome, situated in the craters of spent volcanoes; and many coast lagoons, such as the Venetian lagoon, the ample Val di Comacchio, situated north of Ravenna, the lakes of Lesina, of Salpi to the north and south of the spurs of Gargano, and several others.