FLUMES AND "THEIR STRUCTURE. 1 39 



have them well bolted or provided with braces, that are 

 keyed as tight as possible. Iron bolts or hasps are 

 best. Cast-iron pipes of sufficient diameter or sheet- 

 steel tubes may be used with favorable results. It 

 should not be forgotten, when deep and wide depres- 

 sions are to be crossed, that the Great Architedl of the 

 Universe, in providing that water should rise to its own 

 level, has done away with the necessity for tall and 

 costly trestles. The Moors, whose works still remain 

 as a witness of their construdlive skill, understood the 

 use of this beneficent provision, and employed it in 

 works that would not disgrace an engineer of the 

 present time. 



