EXAMPLES OF WALL SECTIONS. 



139 



Q/-OO 



I SS-txTExtreme H. W. 



79.00 



SCALE 

 9 



ip FEET 



FIG. 117. 



and were timbered throughout. The poling boards for support- 

 ing the sides were 2 inches thick, with walings 4 feet apart 

 vertically, and struts or shores 7 to 8 feet apart horizontally. 



The walls (Fig. 117) are 17 feet thick at the bottom, and 

 5 feet 4 inches at the top ; the front face is battered 1 in 12, 

 whilst the back is vertical up 

 to the level of the mud, above 

 which there are two offsets. 



The wall is constructed en- 

 tirely of masonry set in hy- 

 draulic mortar, the face joints 

 being afterwards raked out and 

 pointed with Portland cement. 

 The body of the work consists 

 of blue basalt rubble masonry, 

 whilst the face consists of ashlar 

 in courses 9 inches high, laid in 

 header and stretcher courses, 9 

 inches and 18 inches alternately, 

 with binders 18 inches square 

 and 3 feet long placed about 6 feet apart horizontally and 3 feet 

 vertically. The coping consists of two stretchers to one header, 

 the former being 3 feet high, and the latter 1 foot 6 inches. 



Quay Walls at Rouen. 1 At Rouen the quays have been con- 

 structed in a peculiar manner, which the experience of the 

 engineers attached to the port has gradually improved, and 

 which have been imitated in many similar cases where quay 

 walls have had to be constructed on the banks of rivers. The 

 wall is built upon piles driven down to the chalk and constructed 

 independently of the dam which forms the real embankment to 

 the river ; by this arrangement the wall is, as it were, inde- 

 pendent of the embankment, and the tide is free to rise behind 

 it. The structure is, however, connected to the dam by a plat- 

 form in masonry built also on piles, the lower part being at the 

 level of mean low tide ; this masonry is tied back by iron rods 

 passing through the embankment to masonry anchorages ; the 

 top of the masonry platform is filled in with chalk, and forms 

 the foundation for the road constructed on the top of the quay. 



The section (Fig. 118) shows the form of wall adopted; im- 

 mediately on the top of the piles is laid a mass of concrete, 



1 Engineering, vol. xlviii. p. 424. 



