190 



RENNIE'S BRIDGES. 



PART VII. 



every part should have a perfectly true permanent bear- 

 ing. Great care was also taken in the selection of the 

 blocks. The exterior of the piers was constructed of 

 hard silicious stone brought from Craigleith Quarry near 

 Edinburgh, and Dundee ; the interior, from the bottom 





. 



SOUTHWARD BRIDGE. 

 [By Pcrcival Skelton, after his original Drawing.] 



of the foundations to the springing of the arches, of 

 hard Yorkshire grit ; while that part of the piers and 

 abutments from which the arches spring consisted of 

 the hardest and closest blocks of Cornish and Aber- 

 deen granite : in fine, it may be affirmed that a more 



