WORKS AT CHERBOmtG. 2G9 



Wlien tne block is sufficiently solidified to bear 

 submersion, the mould is removed and the block is 

 sunk into the sea. But the diver must have first 

 prepared the foundations of this cyclopean wall on a 

 perfect level. Provided with levers aud other tools, 

 he raises the block, and places it in the exact position 

 indicated by the engineer. The care demanded by 



Harbour sssssr*#T=rErCT»S F Level of Uie sea at luVh-tide. 



Fig. 51. — Vertical Section of Breakwater at Cherbourg. 



A. Rock work of rough stones, D. Foundation of artificial stone. 



B. Unwroiight blociis. E, Wall laid in Iiydraulicraortai*. 



C. Blocks of squared stone. F. Gi-auite facing. 



this process renders it necessary that the divers 

 should be continually descending and ascending, in 

 order to examine the work on all sides. Furnished 

 with the apparatus we have described, they can, by 

 means of a simple tap, fill or empty their caoutchouc 



