TRAINING-WALLS AT ROUEN. 



141 



a coating of quick -setting cement. The foot of the embankment 

 is protected by a toe, about 6 feet in width, placed at low-water 

 level ; and where it is exposed to the " bore " it is still further 

 protected by sheet-piling. 



The bore sweeps along at certain periods of the tide with a 



i High Water Spring_Tides_ 



Section of Training Walls adopted -i-hen 

 is submerged. Foot of -wall protected by Sheet 

 filing. 



.0-06' 



FIG. 119. 



speed of 26 feet per second, and during the equinoxes often 

 attains a height of 10 feet 



Gourock Quay Walls. 1 In carrying out the concrete quay 

 walls at Gourock, Mr. Graham, C.E., of Glasgow, adopted a 

 method of construction by which the use of costly coffer-dams 

 and pumping was avoided. 



A temporary staging was first erected along the lines of 



LWJ/lark 



Section of Training ll'all adopted when, 

 wall is uncovered by High Tides, 



FIG. 120. 



the wall to carry the pile-drivers, concrete-mixing machinery, 

 cranes, etc. 



The sheet-piling forming the casing for the concrete con- 

 sisted of timbers from 42 feet to 55 feet long ; the front piles 

 were 12 inches thick and those at the back 9 inches. 



The piles were bolted together in sets of three, shod and 



1 Engineering, vol. xlvii. p. 326. 



