RAILWAY CONSTRUCTION. 97 



wrought-iron, or steel, of suitable form and arrangement to 

 ensure strength and stability. Not only must the piers be 

 strong enough to carry the weight that may be brought upon 

 them vertically, but they must have sufficient width of base to 

 ensure lateral steadiness. The design should admit of facility 

 of erection, with a minimum of scaffolding, and the pieces should 

 be of convenient length and weight for transport. The lower 

 length of river piers, or portion liable to be in contact with 

 flood- water, should be of solid masonry, to resist the action of 

 the water, or of any debris brought down by the current. More 

 than one fine viaduct has been swept away for want of due 

 attention to the latter precaution. 



Fig. 97 illustrates a type of pier composed of cast-iron 

 columns, well braced and stayed with wrought-iron. The ends 

 of the columns and all contact surfaces should be properly 

 turned and faced by machinery to ensure true and perfect joints, 

 and the socketed ends should be turned and bored to fit 

 closely. The latter is important, and if not carefully carried 

 out, a slight sliding movement of the flanges may take place, 

 and throw undue strain on the bolts. 



Fig. 98 shows a very similar pier, constructed entirely of 

 wrought-iron or steel. 



Each of the above-described piers has a liberal amount of 

 taper or batter, both in the front and transverse elevation. 



The size and number of the columns, and the dimensions of 

 the braces or stays, will depend upon the height of the pier and 

 the weights and strains to be sustained. 



Many important and lofty viaducts have been erected on this 

 principle of iron piers springing from masonry foundations, 

 more particularly across deep rugged ravines abroad, where iron 

 piers offered the only practical, substantial means of dealing 

 with what appeared otherwise an impossibility. 



Fig. 99 is a sketch of the Kinsua Viaduct on the Erie Rail- 

 way, one of the highest railway viaducts in the United States. 

 In the transverse elevation the piers have a large amount of 

 taper ; but in the front elevation they ai*e vertical, and of width 

 to correspond to one of the small spans of the main girder. This 

 arrangement of long and wide base gives great stability to the 

 pier. The spans of the girders, which are of the ordinary lattice 

 type, are not large, being 61 feet for the clear spans, and 38 feet 

 6 inches for those over the piers. The principal interest is in 



H 



