EXAMPLES OF WALL SECTIONS. 



137 



They consist of piers 32 feet 9 inches deep by 13 feet 1 inch 

 wide, which carry arches of 39 feet 4 inches span. Beneath these 

 arches the facing that maintains the surface of the quay is laid 

 at its natural slope. The tops of the quays are 21 feet above low 



ISO JC 

 JO-OO 1 



(-12-00) 



r 



FIG. 107. 



water, and the foundations are sunk at least 3 feet 4 inches in 

 the bed of marl that underlies the bed of the river Garonne 

 (Figs. 107, 108). 



The walls of the floating basin are on compact clay, met 

 with at a level of 39 feet below low- water mark. A length of 

 750 feet is founded on piles driven 40 inches apart longitudinally, 

 and 68 inches transversely. At intervals of 165 feet, the wall is 



(6-57) 



FIG. 108. 



strengthened by blocks of masonry 16 feet 4 inches wide, and 

 19 to 26 feet long. The remainder of the basin walls stand on 

 blocks placed about 42 feet apart, connected by arches of 26 feet 

 3 inches span. 



