172 NOTES ON DOCKS AND DOCK CONSTRUCTION. 



The maximum range of spring tides at the port of Genoa 

 does not exceed two feet. 



The site of the works (Figs. 151, 152) being in open water, 

 special means of construction were necessary. A system of 

 floating caissons proposed by Messrs. Zschokke and Terrier was 



Fio. 151. 



therefore adopted, not as the most economical, but as affording 

 the best guarantee of success from a technical point of view 

 (Figs. 153 to 155). 



Each caisson is 105 feet by 225 feet, or sufficient to take in 

 the entire width of the dock. The working chamber is G feet 



