p. 398 ) It was 1101 surprising that the Po, near the sea, should bc named the seven seas; for all the country (the plains of Venice) was then a morass, frequently covered with the sea, so that canals were dug, partly for agriculture, and partly for navigation. This aquatic plain extended. by the inundations of the Po, caused by the Trebia, and other rivers, far into Cisalpine Gaul. Camillus SC3l1I'LlS, 115 B. C. drew navigable canals from Placentia to Parma. (Livy, lib. xxxviii.) In the correspondence between Trajan and Pliny, mention is made of sluices, hut there is no reason to think that locks with double doors are meant, because no such were known to have been executed hy the Rnmans. If they had once been adopted, their utility would have ensured them from falling into disuse.
Modern Italy.
AIodern Italy, having recovered from the stupefaction which succeeded the dzstruction of the Roman empire, brought into action the seeds they had preserved of east ern knowledge, and as soon as property became pro tected by regular government, and commerce had intro duced wealth, the first efforts of industry and art were directed to the drainage of marshy lands, and the con struction of banks to regulate rivers, \vhose beds had been raised by gravel and mud brought down from the mountains. The next step was artificial canals for irri gation and inland navigation, and finally, sluices with double doors were completed. This most important step in the progress of inland navigation, was accom plished in the year 1481, by two engineers of the town of Viterbe. (Zendrini, c. 12.) These improved sluices were soon afterwards duly appreciated by that enlight ened and scientific artist, Leopardi de Vinci, in the canal of junction executed under his direction at Milan ; and inland navigation became so important, that the Italian governments enacted many laws respecting it, and the most learned men of the country wrote elaborate treatises resperting the management of water.
On entering the Milanese, many canals are found car rying water for irrigation, and two that are navigable, and these form a communication between the Tesino and the Adcla, and unite at Milan. Near to 011eggio, a canal has been taken from the 'resin°, which passes Buffolaro, Biagrasso, and Arsago, to Milan ; its length is 15 miles ; it is named Naviglio Grand. Flom Abiato, a branch of about 11 miles proceeds southwards ; its breadth at the bottom is 46 Fiend) feet, at top water 130 feet. It was in 1257 extended to Milan, and was enlarged in 1269. The Herugando branches from the last mentioned. It was made in 1457, and has now 11 sluices.
Front the right bank of the river Adda, near Con cessa, (the ancient Trizzo,) the canal named Martesena, is taken off. It is 24 miles in length, and 33 feet in breadth ; it is in some places sustained by thick walls and earthen mounds, 110 feet above the level of the river. Some French authors attribute this great work to Louis XII. and Francis I. Italian authors ascribe it to Francis Forza I —and state, that, on the 1st July, 1457, he named commissioners for the work. It is cer tain that Louis Forza, the son of Francis, rendered it navigable round Milan, and formed depots for merchan dise. It was at this time, 1497, that the five sluices were introduced.
'The great canal of Tesino, and the branch which goes from the side of Pavia, unite at Milan. The Muzza is anothel canal drawn from the Adda ; it commences near Cassano, and re-enters near Castiglione, which is 40 miles distant. Upon this length there are various branches for irrigation, in the districts of Milan and Lodi. The Adda, above the intake of the Montesano, is not navigable to the lake Como ; it was attempted in 1519, but did not suc ceed. The fall is 84 feet in five miles. The channel is rocky and irregular.
The canals of Piedmont are less ancient and less con siderable than those of the Milanese ; but there are five of some consequence. 1. The Naviglio d'Inea, of 38 miles, which unites the Dora Baltea with the Sessia. A branch from this, of 13 miles, joins the Gardena river. 2. A canal of 27 miles, from Dora Baltea, a little above the falls of the Po, which, after passing Trino, falls into the Po, four miles below Casal—these two canals are nearly parallel to the Po, and substituted for it. 3. A canal of three miles from the mouth of the canal of Trino. 4. The Naviglio Novo, which proceeds from Sturo, near Coni, to the Po, near Carmagnol, 10 miles a'oove Turn'. 5. Above Novare, a canal of three miles unites the Cogno with the Tordopio river. The canal of Mora Noviglio begins at the end of the canal of Novare.
Along the Po, below the 'Milanese, the canal named Al binea, 20 miles, commences in the Pogna, near Nibiola, and falls into the Po near Albignolo, 10 miles above Pavia. In the Cremona, the canal named Naviglio della Communila, between the Lerico and the Oglio, falls into the Po near Cremona, four miles below the mouth of the Adcla. A canal of three miles goes from that of Cre mona, and falls into the Oglio. Another canal of eight miles begins in the Po, near Cassal Maggiore, and falls into a river which joins the Oglio below Gustalla.