TRANSPORTATION OF THE DEBRIS 195 



made a speed of 3 to 34 miles per hour, and although built 

 especially for the lakes they could be sent to sea. Their construc- 

 tion was simple and economical and it was found that the pressure 

 engines were preferable to those of medium pressure, as being 

 simpler, lighter and easier to keep in working order and conse- 

 quently could be relied upon for continuous work. 



To-day, instead of simple dumping scows, are built regular sea- 

 going hopper steamers with a capacity of about 1000 tons, and able 





FIG. 64. Sea-going Steam Hopper. 



to navigate in any kind of weather. Fig. 64 shows one of these 

 hopper steamers as built by the firm A. F. Smulders of Rotterdam, 

 for the Russian Government. 



Dumping scows are far more economical than the hopper steamers 

 both in the original cost of construction and in the running expenses. 

 For this reason contractors in the equipment of their plants will 

 always prefer dumping scows to hopper steamers. The latter, 

 however, are more reliable for continuous work and supply a rapid 

 and uninterrupted means of transportation for the debris of the 

 dredges which work day and night on river and harbor improve- 



