CHAP. Xll. 



THE MBNAI BRIDGE. 



451 



progress, and the masonry proceeded so rapidly that 

 stones could scarcely be got from the quarries in suffi- 

 cient quantity to keep the builders at work. By the 

 end of June about three hundred men were employed. 



The two main piers, each 153 feet in height, upon 

 which the main chains of the bridge were to be suspended, 

 were built with great care 

 and under rigorous inspec- 

 tion. In these, as indeed in 

 most of the masonry of the 

 bridge, Mr. Telford adopted 

 the same practice which he 

 had employed in his pre- 

 vious bridge structures, that 

 of leaving large void spaces, 

 commencing above high 

 water mark and continuing 

 them up perpendicularly 

 nearly to the level of the 

 roadway. " I have else- 

 where expressed my con- 

 viction," he says, when 

 referring to the mode of 

 constructing these piers, 

 " that one of the most 

 important improvements 

 which I have been able to 

 introduce into masonry con- 

 sists in the preference of 

 cross-walls to rubble, in the 

 structure of a pier, or any 

 other edifice requiring strength. Every stone and joint 

 in such walls is open to inspection in the progress of the 

 work, and even afterwards, if necessary ; but a solid 

 filling of rubble conceals itself, and may be little better 

 than a heap of rubbish confined by side walls." l The 



SECTION OF MAIN PIER 



' Life of Telford,' p. 221. 



2 G 2 



