280 



ENGINEERING. 



preferable; the French Government has cho- 

 sen the narrow gauge for branch lines ; and 

 even in Scotland such a road has just been 

 Duilt. Most important among recent engineer- 

 ing achievements are the building of the East 

 Kiver Bridge between Brooklyn and New York, 

 and the boring of the great adit to drain the 

 mines of the Comstock lode in Nevada, car- 

 ried out by the energetic Sutro, who had great 

 moral as well as physical difficulties to over- 

 come. The same may be affirmed of the rapid- 

 transit overhead railways in New York, which 

 were opened in the past year. Whether a 

 better plan of rapid transit might have been 

 devised, or whether the elevated roads might 

 have been constructed in a better manner, is 

 now a dead issue, with whatever vigor and sin- 

 cerity it has been contested in past years ; and 

 the public seem to be making up their mind 

 with growing satisfaction to this method of 

 rapid transit with all its disadvantages, since 

 it has become an accomplished fact. In Europe 

 the chief work now going on is the piercing of 

 Mount St. Gothard by the longest railroad tun- 

 nel in the world, which will be accomplished 

 within two years if the energy and resources 

 of M. Favre do not find the physical difficulties 

 insuperable. 



The suspension bridge over the East River, 

 to connect Brooklyn and New York cities, 

 is now approaching completion after nine years 

 of intermittent labor. This great bridge is the 

 chief work of the late John A. Roebling, and is 

 being completed under the direction of his son, 

 W. A. Roebling. It is a suspension bridge of 

 the usual form with wire cables, similar to those 

 constructed by the same engineer at Niagara 

 and Cincinnati. The length of the bridge be- 

 tween the anchorages is 3,475 feet. The piers 

 are two, situatad at the edge of the river on 

 each side. The superstructure of the bridge is 

 to be an iron framework, 85 feet in width, sup- 

 ported by the four main cables, which have a 

 diameter of 16 inches each and a strength of 

 160,000 Ibs. per square inch of their section, 

 their total strength being 5,000 tons. The bridge 

 will be supported also by straight stays running 

 from the top of the piers and attached to the 

 bottom of the bridge, which are said to be 

 strong enough to prevent the bridge from fall- 

 ing, without the main cables. The height of 

 the bottom of the bridge at its lowest portion 

 above the river is 135 feet at high water. 

 The height of the towers is 268 feet above high- 

 water mark. The deflection of the cables is 

 feet. The total length of the bridge, 

 from the entrance on the New York side 

 at Chatham Street, opposite City Hall Park, 

 to the Brooklyn entrance at the square be- 

 tween Fulton, Prospect, Washington, and Sand 

 Streets, is about 6,000 feet. The entrance to 

 the New York approach, the center of which 

 falls at the north line of the building occupied 

 as the office of the "Daily News" paper, is 

 distant 1,o62* feet from the New York anchor- 

 age, m the block between Cherry, Water, and 



Dover Streets ; the distance from the anchor- 

 age to the pier is 940 feet ; the clear span over 

 the river is 1,595 feet; the distance from the 

 opposite pier to the Brooklyn anchorage, at 

 James Street, is likewise 940 feet; and the 

 length of the Brooklyn approach is 836 feet, or 

 a little more than half that of the New York 

 approach. The roadway of the bridge, 85 feet 

 broad, is to be occupied by two railways, two 

 wagon-ways, and a footpath. The carriage- 

 ways are to be on each side of the roadway, 

 the railways within them, and the footway in 

 the center of the bridge. For a distance of 

 600 feet on the New York side, and for a cer- 

 tain distance on the Brooklyn side, the road- 

 way of the approach is 100 feet in width, the 

 extra width being taken up by two additional 

 footpaths which come to an end where the 

 roadway is narrowed to 85 feet. 



The roadway of the approach is supported 

 by a series of semicircular arches, which rest 

 upon piers of granite and brick. In the piers 

 open cells are left, for the sake of economizing 

 the material. The buildings will be demol- 

 ished for a space 110 feet broad to make room 

 for the entrance. The roadway rises in a gradi- 

 ent of 3 J feet in each 100 feet from the entrance 

 near the City Hall to the summit of the anchor- 

 age. The roadway in the three suspended spans 

 will be as nearly as possible perfectly level. 

 The north side of the New York approach will 

 run close to the adjacent buildings, but on the 

 south side a street will be made of varying 

 width, extending its whole length. The. ex- 

 terior of the arched masonry forming the ap- 

 proach will be of dressed granite in two colors. 

 Within the arches two floors will be constructed 

 on cross-beams, the highest being 30 to 37 feet 

 above the ground. The rooms thus formed 

 will be rented for warehousing arid the like. 

 At the edges of the roadway the approach will 

 be ornamented by a pierced stone parapet. At 

 the crossings of streets the arched structure is 

 interrupted and the roadway carried over on 

 bridges of different construction. The bridge 

 crossing Franklin Square is to be an iron truss 

 skew bridge with spans of 170 and 210 feet. 

 Cliff Street will be crossed by a stone and brick 

 structure of 51 feet 8 inches; Yandewater 

 Street by a similar bridge of 40 feet span. The 

 other bridges will be simple box-girders. The 

 bridges will be constructed in an ornamental 

 style. The roadway will be ornamented further 

 by large and handsome gas-lamps. The two 

 railways will not be crossed by locomotives, 

 but the trains will be moved by endless wire 

 ropes worked by large steam-engines at the ter- 

 mini. Special clutching devices have been de- 

 signed for attaching the cars to the ropes. In 

 the wagon-roads iron and steel trams about 14 

 inches wide are to be laid, which will afford a 

 track for street-cars or any kind of carriages, 

 and will accommodate wheels of any length of 

 axle. 



The four main cables^ 16 inches in diameter, 

 are composed of parallel steel wires bound to- 



