ENGINEERING. 



329 



immense work will be found. Herewith are 

 given elevation and plan of the central spans, 



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with cross-sections at centers and at piers, and 

 a cross-section of roadway, showing the four 

 tracks. In brief, the history of this structure 

 is as follows: Twenty years ago the North 

 .British Railway Company was authorized by 

 Parliament to construct a bridge five miles 

 above the present one, but a series of borings 



CROSS SECTION AT CENTER. 



CROSS SECTION AT P1E. 



showed that there was no suitable foundation. 

 In 1873, another act authorized the construc- 

 tion of a suspension bridge at the present loca- 

 tion, but the fall of the Tay bridge led to the 

 rejection of the design, and the present plan for 

 a cantilever or continuous girder bridge was 

 adopted. It is the result of consultation be- 



CROSS SECTION OP ROADWAY. 



tween Messrs. Baker, Fowler, Harrison, and 

 Barlow, engineers representing the different 

 railway interests involved. The contract calls 

 for two spans of 1,710 feet each, two of 675 

 feet each, fifteen of K>8 feet each, and five of 

 25 feet each, aggregating about 1 mile. The 

 contract price is $8,000,000. 



The Blaanw Krantz Bridge, just finished in 

 Cape Colony, Africa, has excited considerable 

 interest among engineers, owing to the origi- 

 nality of its construction and the peculiar con- 

 ditions that rendered this construction the 

 most available under the circumstances. The 

 designer and engineer is Mr. Max am Ende. 

 This bridge crosses a ravine on the railway 

 from Port Alfred to Graham's Town, at a height 

 of about 200 feet. Its length is 480 feet, and 

 width of roadway 15 feet, the track gauge be- 

 ing 3 feet 6 inches. The central span is an arch 

 of 220 feet and about 90 feet in height, the re- 

 maining space on either side being crossed by 

 balanced girders, 144 feet long, resting on iron 

 piers. These girders have one end anchored 

 in the retaining walls, while the other rests in 

 a sliding bearing on the top flange of the main 

 arch. It will be remarked that the dimen- 



