ENGINEERING. 



255 



timatetl at 8$ metres. If 9,400-horse power is 

 applied it is calculated that the lake will be 

 drained in about two years, at the rate of 

 4, .".i MI cubic metres per minute. The only effi- 

 cient power hero applicable is supposed to be 

 the steam-engine. After the steam-pumps 

 have done their business, dredges will have to 

 be employed to dig out the bottoms of the 

 canals, and clear away the mud, where large 

 structures have to be built. For the founda- 

 tion of many of the heavy structures it will be 

 necessary to sink piles and bundles of fascines, 

 as nas been done in the making of the great 

 Amsterdam Canal. The entire work, it is es- 

 timated, can be completed in from twelve to 

 sixteen years. The surface drained will be 

 196,670 hectares, or about 795 square miles, of 

 which area about one-tenth will be taken up 

 by roads and canals. It is supposed that, with 

 all allowances, there will be about 150,000 hec- 

 tares of fine, tillable land. The expense of the 

 undertaking is estimated at 240,000,000 francs, 

 a large estimate, exclusive of interest. If the 

 Government should carry out the undertaking, 

 as seems most likely, it is calculated that it 

 would bring in, after completion, an annnal 

 revenue of 1,880,000 francs. 



Two enterprises for the reclamation of large 

 submerged tracts are successfully in progress 

 in Italy. The Ferrara Marshes, in Northern 

 Italy, are being drained by means of steam- 

 pumps, constructed by John and Henry 

 Gwynne, of Hammersmith, England. The area 

 to be reclaimed is 200 square miles. The en- 

 gines lift 2,000 tons of water per minute 

 through an average distance of seven feet three 

 inches. The maximum lift is twelve feet. The 

 water is discharged into the river Volano, at 

 Corcligoro. Another large enterprise is the 

 drainage of Lake Fucino, which lies about 55 

 miles east of Rome, and has an area of sixty-one 

 square miles, by means of a siphon 1,500 yards 

 long, from canals which have been dredged out 

 at the bottom. The works have been going 

 on many years, at the expense of the late 

 Prince Torlonia, and the enterprise will soon 

 become remunerative. This area was drained 

 by the Emperor Claudius, and the ancient 

 works were suffered to go to decay in the 

 middle ages. The project was at first designed 

 to restore the Roman works, and a company 

 was formed in 1855 for that purpose, and the 

 work was intrusted to M. de Montricher, a 

 well-known French engineer. This was found 

 impracticable, and, the Prince Torlonia assum- 

 ing the entire responsibility, the present works 

 were constructed. About 50,000,000 francs 

 have been expended upon them thus far. 



There are suggestions of extensive improve- 

 ments in the harbor of Genoa, and various 

 plans have been proposed for the work. It has 

 long been the dream of the Genoese to make 

 their harbor the best in the Mediterranean, and 

 regain their ancient commerce and prestige on 

 the seas. A nobleman of Genoese birth, it is 

 said, has presented the city with the sum of 



20,000,000 francs, to be devoted to harbor im- 

 provements. 



The tunnel under the English Channel, for 

 the commencement of which companies have 

 been formed in London and Paris, it is pro- 

 posed to construct on the route proposed by 

 air John Hawkshaw, from St. Margaret's Bay 

 to a point near Sangatte on the French coast. 

 In this course it is expected that it will pass 

 through chalk-beds the entire way, while in 

 the route proposed by M. Thom6 de Gamond 

 it is known that several different strata would 

 be encountered. The distance across the Chan- 

 nel in the proposed course is 22 miles, which, 

 with the long approaches necessary, would 

 make 31 miles altogether. Shafts are to he 

 sunk on either shore to the depth of 450 feet 

 below high-water mark. At that depth drift- 

 ways are to be driven, which will serve for the 

 drainage of the works when in progress, and 

 of the tunnel permanently. The tunnel will 

 commence 200 feet above the driftway, with 

 an inclination of one foot in eighty down to 

 the junction with the driftway, and then of 

 one foot in 2,640 to the centre of the Channel, 

 where it will meet that driven from the other 

 side. The dimensions of the tunnel will be 

 those of an ordinary railroad-tunnel for two 

 tracks. A driftway, nine feet in diameter, it 

 is proposed first to carry entirely through, 

 which can afterward be enlarged to the size of 

 the tunnel. A machine for tunneling in chalk 

 has been invented by Dickenson Brunton, an 

 English engineer, which has been successfully 

 tried upon the bed of gray chalk through which 

 the tunnel is to be made. It works similarly 

 to an ordinary board-auger, cutting off the 

 chalk in slices, which fall upon an endless 

 band, and are loaded upon wagons. The ma- 

 chine, it is found, can cut a driftway of seven 

 feet diameter at the rate of something over a 

 yard an hour. At that rate it would take two 

 years to complete a driftway under the Chan- 

 nel witli a machine starting from each side. 

 The expense of completing such a driftway is 

 estimated at 800,000, including interest upon 

 the outlay. Engineers and contractors of ex- 

 perience have calculated that, after the drift- 

 way should be completed, it would take four 

 years' time and 4,000,000 only to enlarge it 

 to the dimensions of a railoau-tunnel, and to 

 construct the junctions with the railways 

 on either side. It seems certain now that 

 the commencement of this work will soon be 

 made and its practicability tested. The com- 

 panies which have been formed for this pur- 

 pose are to unite with the French and English 

 railways interested, and with the Rothschilds 

 of London and Paris, in making up the sum of 

 160,000, to be expended upon sinking a shaft 

 on either side to the depth of 450 feet, and driv- 

 ing a headway a short distance under the sea. 



The project of a tunnel under the North 

 River from New York to Jersey City, for rail- 

 way transportation, for which a company was 

 formed some time ago, gave rise to a long 



