232 



THE OLIVE MOUNT CUTTING. 



HAP. XII. 



approaches were of comparatively small importance, and 

 in determining the rise of his arch the engineer selected 

 any headway he thought proper. Every consideration 

 was indeed made subsidiary to constructing the bridge 

 itself, and the completion of one large structure of this 

 sort was regarded as an epoch in engineering history. 

 Yet here, in the course of a few years, no fewer than 





OLIVE MOUNT CUTTING. [By Percival Skelcon.] 



sixty-three bridges were constructed on one line of rail- 

 way ! Mr. Stephenson early found that the ordinary 

 arch was inapplicable in certain cases, where the head- 

 way was limited, and yet the level of the railway must 

 be preserved. In such cases he employed simple cast- 

 iron beams, by which he safely bridged gaps of moderate 



