240 



A TREATISE ON DREDGES AND DREDGING 



bins are seldom used, and in many cases the bucket loads arc dumped 

 directly into wagons or cars, or else the sand is piled along the bank. 



Fig. 79 illustrates some of the machines for unloading barges 

 along the Mississippi River. 



Filling Marsh Lands. The transportation of the excavated 

 materials to the dumping place is one of the most expensive items 

 of dredging. Engineers have devised schemes, not only for eliminat- 

 ing this item of expense, but if possible to obtain some benefit from 

 this bulky and otherwise useless material. Small drainage canals 

 have sometimes been excavated at a very low cost owing to the 



FIG. 79. Machine for Unloading Sand from Barges. 



fact that the debris was deposited directly alongside the cut, thus 

 entirely eliminating their transportation. Some harbor and river 

 improvements have also been made at a comparatively small cost 

 on account of using the dredged materials for filling up lowlands 

 located along the water front. In a few instances dredging operations 

 have been made profitable by reclaiming either for agricultural 

 or industrial purposes some marshy lands which were not only 

 valueless, but dangerous to the health of the surrounding population 

 as breeding places for mosquitoes. But in these particular 

 the filling up of lowlands was of a secondary importance. 



It is only recently that dredging has been undertaken for the 



