LADDER OR ELEVATOR DREDGE 73 



0.034 for hard clay and indurated mud and 0.026 for soft mud and 

 light sand. 



Manufacturers have built a very large variety of ladder dredges. 

 These, however, for sake of classification, according to the locality 

 in which they have to work, can be broadly grouped as follows: 



1. Sea-going dredges ; 



2. Harbor and wide river dredges. 



3. Canal and narrow river dredges. 



