100 



A TREATISE ON DREDGES AND DREDGING 



The following table shows the amount of solid material that 

 can be raised by pumps and the H.P. required: 



TABLE No. 1. 



Mr. A. W. Robinson states, "The efficiency of a good centrifugal 

 pump for water is from 55 to 65 per cent under ordinary conditions; 

 that of a dredging pump is from 48 to 55 per cent." 



Table No. 2 gives revolutions of various kinds of centrifugal 

 pumps, while Table No. 3 gives the capacity of dredging pumps. 

 All of the tables in this chapter" are taken from the catalogue of the 

 Morris Machine Works of Baldwinsville, N. Y. ; builders of centrifugal 

 pumps. 



Discharge Pipes. Discharge pipes are of the same material and 

 dimensions of those composing the suction pipe. The discharge 

 pipes generally rise vertically from the pump and then bend toward 

 the point of discharge. When the suction dredge is of the hopper 

 type the discharge pipes run into the sand bins, otherwise they aro 

 turning toward one side of the vessel in order to be emptied into 

 scows to be placed alongside of the vessel. But with the suction 

 dredges which are not of the hopper type, the most convenient 

 way of disposing of the de*bris is to fill up lowlands along the shores 

 and in such cases the discharge pipe is connected with a long line of 

 pipe placed on floats, thus conveying the dredged materials to disi ant 

 points. 



The velocity of flow in the discharge pipe varies from S to 16 ft. 



