GARIBALDI’S TIBER SCHEME.

Globe, Volume IV, Issue 301, 31 May 1875, Page 4

GARIBALDI’S TIBER SCHEME.

{Daily News.)

The first project of diverting the Tiber through the Teverone bed up to Ponte Mamolo, then bringing it down headlong to the sea, has been abandoned on financial and technical grounds, and four separate projects substituted:— 1. The diversion of the Tiber on the left of Ponte Molle, so that instead of its winding through the city it would run parallel outside the walls, and re-enter its old bed two or three miles south of Rome. 2. The construction of a port capable of receiving vessels of the largest dimensions near the mouth of the Tiber at Fiumicino, with a large breakwater on the right of the principal branch of the river to protect the entrance into the port from the winds, and from being choked up by the sea sands. By means of a saltwater canal and a system of flood gates, small vessels would ascend from the port to the Tiber and vice versa. These works to be commenced as soon as Parliament sanctions the, undertaking. 3, As the completion of the project, a regular system of agricultural and engineering works throughout the Agro Romano for the purpose of drainage and purification of the air. 4. A diversion of the Teverone for the purpose of irrigating the Agro Romano, which channel, starting above Tivoli, would empty itself into the Tiber near the marshes of Ostia.

I should add that some propose, instead of turning the Tiber to the left of Home, to cut a canal which, starting from the north of the city, will lead the river across the Fossa Pisana, and bring it down the Fossa till it rejoins the Fiumicino branch of its own bed. According to the engineers Landi and Amadei, all these projects are feasible, but their survey and soundings have been so superficial that very slight importance can be attached to their opinion. Ever since the great inundation of 1598, when the Tiber covered certain parts of the city 7ft deep, to 1870, when the water rose s£ft, project after project has been formed to save the city from a recurrence of similar disasters. Some of the schemes were limited to lowering the maximum level of the Tiber in its bed by excavations, to prevent the waters from overflowing; while the more radical reformers proposed the partial, and even the total expulsion of the river from the city. Of these the most important projects are those of the engineer Passenti, who is for the rectification ” or the substitution of straight channels for the now tortuous course of the river below the city, and that of the engineer Canevari, who proposes to enlarge the bed of the river within the city, to dredge and deepen it, and to erect embankments, or even walls, on the right and left, so as to contain the waters at their highest level. A very intelligent engineer, who has not yet made his idea public, proposes a sort of compromise between Passenti and Canevari—i e., to cut a few straight channels, but not so many as those proposed by Passenti, to enlarge and dredge the bed of the river, to repair and fortify the old walls where they exist, to block up the doors and windows of the houses on the banka where they are too low, and to furnish the sewers with valves. The cost of Passenti’s scheme, which the Government deemed insufficient, was estimated at 11 millions, that of Canevari at 40 or 50 millions. The compromise sketched above is put down at 10 millions. Garibaldi’s projects are far more radical and darng. Only Julius Csesar conceived a scheme of equal magnitude. Once the river diverted from the city at the confluence of the Teverone, and brought through rock and other impediments down to its bed again in the vicinity of the basilica of St Paul, and the water prevented by gigantic dams from invading the old bed, the latter would be emptied pro tern, and arch foologiets and antiquarians might pursue their researches after historical and artistic treasures and monuments ; or a well-regulated channel of water might be allowed to flow through the city, or the bed be filled up and serve as the public promenade of Rome. But the financial and technical difficulties even of this modification ol Garibaldi’s plan would seem very great. The quantity of earth that would have to be removed is estimated to be 40 or 50 millions of cubic metres, and the coat oI excavation and removal would be

immense, the ordinary rate being 2£f per cubic metre. Of course some of the material is valuable, but in no way proportioned to the cost, which, for the forming of the new bed alone, without taking into account bridge and wall building, would amount to a hundred millions of francs. Now, it is hardly likely that the Roman municipality, the province, or even the Parliament, will guarantee the interest on such a sum for the mere diversion of the Tiber. Indeed, with all the goodwill shown to Garibaldi, and the fact that the Minister of Public Works supplies the funds for the surveys, Minghetti only speaks of “ entertaining a proposition for the guarantee of the interest on ten millions,” and Signor Sella, who may at any moment overthrow his rival on the-financial question, washes his hands altogether of the affair.

The financial difficulties overcome, even then serious technical difficulties remain to be solved. The excavations present no obstacles, it being merely a question of hands and steam-engines, i e, of money, but should only part of the water be turned into the new channel, the remainder being reserved for the old bed in Rome, the diminished mass will, of course, flow witi diminished velocity, and instead of bearing down the turbid deposits brought from the mountains to the sea, will leave then: in the bed, which will gradually become choked up. The waters, decreasing in velocity, will become even stagnant in parts, aid cause ague and fever. If, on the other htnd, the old bed be filled up, the city will be left without a conduit for the sewage and rail water. They will have to be carried away by special conduits; but then, instead of the velocity which the present drains offer the course of the new conduits would te slow and difficult, and the cleansing of :he city slow, partial, and imperfect. Instead of inundations, which happen on an average every twenty or thirty years, we should le menaced by a less visible but still more fornidable foe, i.e, the permanent and ever increasing insalubrity of the city of Rome. Ttese are some of the chief objections raised by competent and impartial persons against the deviation scheme, and I think it right to ftate that they must be met and answered. It seems absurd, say many Romans, since we have got such a splendid river, to banish ;t from our midst. Let us dredge its bed, cut off its tortuous, sinuous meanderings. build embankments as the riverside populations of the Po and Adige do ; but as to getting rid of the river, it is not to he thought of. The construction of a port at Fiumicino is, on the other hand, high’y approved, and deemed not only practicable, but certain of success. Between the propoied port and Ponte Galera, the station on thi Rome and Civita-Vecchia line, which the projected Fiumicino and Rome line would join, lies the Trajan Lake, which Prince Tcrlonia is bent on draining.