12.VJ A TREATISE ON DREDGES AND DREDGING 



has ever seen in connection with earth and rock excavation. Steam 

 shovels and dredges are being used for this work almost exclusively. 

 The dredges are of the suction, ladder, and dipper type. Some 

 are of the hopper type. In spite of the fact that this is the greatest 

 job of excavation undertaken by man, there have been no new types 

 of machines invented or designed for the work, owing to the fact 

 that the U. S. Government is doing the work by day labor, 

 instead of employing contractors, who would no doubt have reduced 

 the cost of the excavation by using machines designed especially 

 for the job in hand. 



