ccliv GENERAL SUMMARY OF SCIENTIFIC AND 



other side. A new iron bridge over the Genesee Falls was 

 completed last year for the Erie Railroad, and opened for 

 traffic. A new suspension bridge over the Monongahela 

 River, at Pittsburgh, was likewise contracted for. It is 

 proposed to employ in its construction immense iron chains 

 instead of the usual wire cables. An iron bridge across 

 the Missouri River, at Atchison, Kansas, was completed on 

 the 4th of August, and opened for traffic during the same 

 month. 



Work upon the new Bergen Tunnel of the Delaware, Lack- 

 awanna, and Western Railroad is progressing rapidly. Ex- 

 cavation was originally carried on from six shafts, which, to- 

 gether with the two outside ends, gave fourteen faces to 

 work upon. The excavation is now about completed on four 

 of the sections, so that there are but six faces at which work 

 is beins; carried forward. Between shafts 3 and 4 there re- 

 mains, at the time we write, 305 feet of heading to be done; 

 between 4 and 5, 228 feet; and between 5 and 6, 109 feet; 

 and in all about 1450 feet of bottom or bench work still to 

 be removed. The total length of the tunnel, from face to 

 face of the portals, will be 42*70 feet. About GOO men are 

 kept at work on the tunnel, the estimated cost of which will 

 be $800,000. The work was begun in September, 1873, and, 

 it is thought, will be completed by July, 187G. 



A railroad tunnel under Newark Bay was likewise pro- 

 posed during the past year. The approach to Jersey City 

 from Newark across the marshes and the waters of Newark 

 Bay (via the New Jersey Central Railroad) is effected by an 

 elevated railway carried upon wooden piles. The unsafe con- 

 dition of this structure during the winter and spring, and 

 the yearly expense involved in keeping it in repairs which 

 has practically amounted to its rebuilding three times since 

 its first completion has led the company to seriously con- 

 sider the practicability of building a tunnel under the waters 

 of the bay from Elizabethport to Bergen Point. Prominent 

 engineers consider the scheme a feasible one. A rouorh.esti- 

 mate places the cost of a tunnel for double tracks, extending 

 a distance of 2^ miles, at $0,000,000, and which, if built, would 

 last for a century. 



The Channel Tunnel project, which contemplates the 

 union of England and France by a submarine railway tun- 



