278 



ENGINEERING. 



tires have also been tried on vehicles, and 

 would give satisfaction on a smooth pavement. 

 If streets were paved with concrete, which 

 might be laid down in movable blocks in the 

 parts overlying sewers, the waste of power, 

 the wear of vehicles and pavement, and the 

 strain on the nerves of the citizens, now in- 

 curred by the jarring and rattling of carriages 

 on the rough stone pavements now in use, 

 would all be avoided. Under the present con- 

 ditions of locomotipn, parallel trams for the 

 wheels, with a footway of ordinary pavement 

 for the horse, would be immensely superior 

 to the cobble, spall, or bowlder pavements now 

 in use. 



A subterranean telegraph between Berlin 

 and Mayence, a distance of 600 kilometres, 

 was completed July 23d. It passes through 

 Halle, Leipsic, and Frankfort. The wires are 

 twisted together and protected by a covering 

 of hemp and iron. This is the first long under- 

 ground cable which has been laid since the 

 failure of the wire between Berlin and Cologne, 

 laid in 1848; although Germany has several 

 shorter lines. The cost of the subterranean 

 telegraph is six times as much as that of the 

 same number of overground wires. This line 

 is one of seven underground telegraphs which 

 are to be laid between Berlin and the west- 

 ern frontier. The mileage of underground 

 telegraphs in Great Britain has been increased 

 from some 2,000 miles in 1870 to over 8,000 

 miles in the spring of 1877. All the metropo- 

 litan wires are laid below the earth, on account 

 of the dangers from aerial telegraphs in cities. 

 A short telegraph-wire has been put up in Chi- 

 na, for the use of Li Hung Chang, the Viceroy 

 of China, to the construction of which no op- 

 position was shown by the populace. Several 

 lines are projected in Formosa by the governor 

 of the island. 



The new tunnel of the Delaware and Lack- 

 awanna Railroad through Bergen Hill, near 

 Hoboken, in New Jersey, was commenced in 

 September, 1873. It was prosecuted by hand- 

 drilling from both ends, and each way, from 6 

 perpendicular shafts. In January, 1876, the 

 headings were all connected. The bottom was 

 leveled in the following May, but the work of 

 enlarging the roof and lining the insecure por- 

 tion with masonry took still a year, and the 

 tunnel was first opened to the passage of trains 

 in May, 1877. The length of the bore is 4,210 

 feet. The masonry projects 35 feet farther at 

 each end, as a protection against falling stones 

 and earth. The tunnel is back-arched, with ma- 

 sonry 22 to 34 inches thick, for 3,100 feet, or 

 nearly three-quarters of the entire length. The 

 eastern entrance is 2,700 feet to the north of 

 the Bergen tunnel of the Erie Railroad, which 

 the Delaware and Lackawanna trains have hith- 

 erto used. It forms an angle^of 40 with this 

 tunnel, and emerges, on the west side of the 

 hill on a higher level, within 50 feet of it, so 

 that the trains cross the Erie track over a 

 bridge. The width of the new tunnel is 27 



feet in the clear, and its height 20 feet 7 inches. 

 It is ventilated by 7 air-shafts, all brick-lined 

 except one. The new line is more direct than 

 the old one through the Erie tunnel, the ac- 

 tual saving in distance being two-thirds of a 

 mile. Besides the boring of the tunnel, the 

 approaches, involving the filling up of bog on 

 the east side of the hill for the distance of 

 three-quarters of a mile, and the construction 

 of no less than 11 bridges, have necessitated a 

 large outlay of capital, altogether $2,787,000, 

 of which the boring of the tunnel through the 

 trap-rock stands for $800,000, and the brick 

 arching for $105,000. In Hoboken there are 

 3 hridges, over which pass 7 tracks over one 

 street, and a 4-track bridge over another, be- 

 sides an iron skew-bridge of 193 feet span over 

 Hoboken Avenue. On each side of the hill 

 there is a bridge over the Erie track, the oil- 

 cars crossing the route again on the east side. 

 The skew-bridge across the Hackensack is a 

 noteworthy structure, on account of the diffi- 

 culty of securing a foundation in the soft bot- 

 tom of the river. The stone piers, which sup- 

 port the iron structure, themselves rest upon 

 1,700 large piles. The bridge has 2 spans and 

 1 draw, each of 200 feet. The engineers of 

 the tunnel were the engineer of the road, 

 James Archbald, and Samuel Rockwell. Be- 

 sides these works, the Delaware and Lacka- 

 wanna Railroad has commenced a ship canal 

 for dock purposes, 3,000 feet long, 100 wide, 

 and 20 deep. 



The longest tunnel in America is that which 

 is being bored for the Baltimore water-works, 

 from the Gunpowder River to Lake Monte- 

 bello, the distributing reservoir, which is about 

 a mile and a half from the city. The length 

 of the bore is 36,510 feet, or 6| miles. It is 

 bored entirely by hand-drilling, through hard 

 gneiss and granite for four-fifths of the dis- 

 tance. The source of the water-supply lies 8 

 miles distant from the city. It is near enough 

 the surface to allow numerous shafts to be 

 sunk, from which the tunneling has proceeded 

 rapidly. The bore is circular in section, and 

 12 feet in diameter. It passes under a rolling 

 surface, and varies from 67 to 353 feet in 

 depth. There are 15 perpendicular shafts, the 

 deepest of which runs down 294 feet. From 

 Lake Montebello the water is conveyed in a 

 conduit, 4,120 feet long, called Clifton tunnel, 

 to a point 1,900 feet outside the city, whence 

 it is distributed to the different parts of the 

 town by 6 mains of 4 feet diameter. 



A great work is now approaching its con- 

 clusion in Saxony the Rothschonberg water 

 adit, for the drainage of the Freiberg mines. 

 This extraordinary tunnel, after 33 years of 

 incessant labor, is now completed for 43 kilo- 

 metres, or 26 English miles, including the 

 branches. When completed, it will have a 

 length of 51 kilometres, or 31 miles. It is 

 already used throughout the length completed. 

 The bore ia perfectly straight for 5 miles, and 

 the bends in the remaining portions are very 



