280 



ENGINEERING. 



ebb-tide, seven powerful pulsometer pumps 

 were employed. The length of the quay is 

 2,233 yards. Coal can be obtained at Milford 

 30 per cent cheaper than at Liverpool. 



The preliminary surveys for the proposed 

 reclamation of the Zuyder Zee have been fin- 

 ished. A dike about twenty-four and a half 

 miles in length will be constructed of sand and 

 faced with clay, reaching sixteen feet above 

 the level of the sea, or about six and a half 

 feet above the highest tide. The thickness of 

 the dike will enable it to resist the heaviest 

 seas. The calculation is to have it completed 

 in from seven to ten years, at a cost of $46,- 

 000,000. 



The Belgian Government and the munici- 

 pality of Antwerp have arranged for a consid- 

 erable enlargement of the harbor, to meet the 

 demands of the increasing commerce of that 

 port. The excellence of the facilities for trans- 

 shipment gives this port the advantage over all 

 others on the west coast of the Continent. 

 The harbor has always a depth of twenty-five 

 feet of water. Its connection with internal navi- 

 gation and with the railroad lines, over which 

 it enjoys favorable tariffs, and the absence of 

 vexatious formalities, have drawn to Antwerp 

 a commerce which now reaches 5,600,000 tons 

 a year. Since the opening of the St. Gothard 

 Railway it commands the great freight move- 

 ment between the North Sea and the Mediter- 

 ranean. The harbor consisted already of seven 

 basins, with a total area of one hundred acres, 

 and two and a half miles of quays. The new 

 works consist in the widening and deepening 

 of the channel of the river Escaut and the con- 

 struction of an additional basin. The contracts 

 were awarded to Couvreux and Hersent. Their 

 amount is 38,000,000 francs. The river will be 

 dredged to a uniform depth of twenty-five feet 

 and a width of three hundred and eighty -two 

 yards. A quay is being extended along the en- 

 tire river front of the city, two and a half miles, 

 one eighth of which only was already built. 

 The sea-wall of the mole is continued in a dike 

 above, to conserve the rectified channel. The 

 new basin is ten acres in area, and gives six 

 thousand feet of wharfage. The great wall, 

 built on foundations sunk from eight to sixteen 

 feet, is thirty feet broad at the base, one tenth 

 narrower at the top, and of an average height 

 of forty-eight feet. Caissons are sunk for the 

 foundations. They are about eighty feet in 

 length. To the top of the caisson a movable 

 iron bell, of the same form, and some forty-five 

 feet high, is fitted, within which the masonry 

 is built up to the surface of the water. The 

 bell, which weighs about two hundred tons, is 

 floated into position, hung in a scaffolding sup- 

 ported by two barges. It is lowered by a sys- 

 tem of jack-screws, very delicately adjusted, 

 which are actuated by .a steam-engine. The 

 same engine works the pumps which fill the 

 caisson with compressed air, and furnishes 

 power also for bringing the materials and the 

 mortar on cranes into the bell. The iron bell 



is first floated to the spot when a fresh section 

 of the wall is to be constructed. The bottom 

 is a couple of feet above the level of the water. 

 When the pontoons are firmly anchored, the 

 caisson is floated under the bell and fitted to it, 

 the joint being closed with India-rubber. A 

 layer of leton is laid on top of the caisson, and 

 the masonry is commenced on this. When the 

 caisson touches ground at low tide, it is allowed 

 to sink into place by withdrawing the pressure. 

 If it does not settle squarely, men descend into 

 the air-chamber, and excavate from the river- 

 bottom until it assumes an upright position. 

 When the caisson is enough charged to pre- 

 vent its swaying at high tide, the water and silt 

 are again removed from the working-chamber. 

 Beton is poured into the chamber through four 

 wells furnished with air-locks. When the ma- 

 sonry is carried up to the level of the water, 

 the four flumes are withdrawn with the bell, 

 and the holes are filled in with leton. The 

 mole is one hundred yards from the former 

 bank, and the space between is filled in with 

 earth. 



The St. Gothard Tunnel was opened to traffic 

 in May. It was the most costly of the Alpine 

 tunnels (see ALPS, TUNNELS OF THE), the cost 

 of construction having amounted altogether to 

 227,000,000 francs, or $44,000,000. It is, how- 

 ever, the straightest and shortest route over the 

 Alps, and must receive the commerce of the 

 whole Rhine Valley and all the adjacent re- 

 gion of Western Germany, of a large section of 

 Eastern France and of the ports of Holland 

 and Belgium, and the Mediterranean trade of 

 the North of Europe. It will make Genoa an 

 outport for German commerce in the Mediter- 

 ranean in the same manner as the Brenner and 

 Semmering Railroads made Venice and Trieste 

 German ports on the Adriatic. This, the most 

 important of the five Alpine railroad routes, 

 would have been completed long before, if in- 

 ternational jealousies and the rivalries of the 

 Swiss cantons had not stood in the way. The 

 road was talked about before 1848, but it was 

 only after the consolidation of Italy and the 

 establishment of the North German Bund that 

 the interests of those two nations prompted 

 them to take up the scheme in earnest. There 

 was a conference held at Bern in 1869, in which 

 Switzerland, the North German League, Italy, 

 Baden, and Wiirtemberg took part. The rival 

 interests of Austria could be disregarded after 

 her defeat at Sadowa, but the French Emperor 

 would have forbidden the construction of a line 

 which would break up the monopoly of the 

 Mont Cenis route if a more convenient pretext 

 for the war with Germany had not present- 

 ed itself. The Swiss cantons were brought to 

 the verge of civil war by disputes over their 

 rival claims. Bismarck overcame their dissen- 

 sions and the French and Austrian opposition, 

 while Cavour pledged Italy to the payment of 

 more than half the cost. Within ten years 

 after the work was commenced the railroad 

 was in operation. The Semmering and Breu- 



