ERECTION OP THE GOKTEIK BRIDGE. 615 



fastened to them and the traveler moved forward. Then the material 

 w ;is loaded on flat ears, pushed out upon the bridge, and transferred 

 from the cars into position. 



Owing- to the height of the bridge and the extreme enanges in tem- 

 perature careful provision had to be made both for the wind pressure 

 and the unusual contraction and expansion of the metal. The bridge 

 was built to carry a load of 2,240 pounds to each linear foot of track, 

 in addition to two locomotives, each weighing 54 tons. It is to with- 

 stand a wind pressure of about 34 pounds per square foot when a train 

 is upon it, and about 5(5 pounds per square foot at other times. These 

 calculations were made by the consulting engineers of the railway 

 company — Messrs. Sir Alexander Rendel & Co., of London, repre- 

 sented by Mr. W. H. Clark. The viaduct was erected under the 

 supervision of Mr. D. Duchars, chief engineer, and Mr. J. A. White, 

 resident engineer. 



As already stated, a portion of the viaduct is located upon a natural 

 bridge. This is a rocky formation which is just wide enough to safely 

 support the towers. Two hundred feet below its summit flows a river 

 which has forced a channel beneath the formation, so that the total 

 height of the bridge above the water is 520 feet. 



