HYDRAULIC DREDGES FOR CHANNELS 125 



The intake of the sand pump is from one pipe 34 in. in diameter, 

 entering in the axis of the pump at the forward side of the casing. 

 This single pipe runs 25 ft. to the forward bulkhead and there 

 branches into two pipes each 24 \ in. in diameter, which separate 

 and pass through the bow of the boat below the water-line 9 ft. 

 apart. These two pipes turn to the right and left along the outside 

 of the bow and then turn forward again and each branch separates 

 into two suction heads. The whole is framed together so that the 

 four pipes, suction heads and cutters are raised and lowered together 

 as one piece. Instead of a radial slipjoint for the suction pipes, as 

 used on the other dredges, there is a vertical flanged joint in the 

 horizontal part of each pipe next to the bow, and the revolving 

 pins that sustain the weight of the aft end of the suction are placed 

 in the prolonged axes of these pipes. 



The cutter for loosening up the material is placed at the outer 

 end of the suction head. It has 22 cast-steel wheel cutters, each 

 having four blades mounted on a steel shaft 6f in. square. This 

 shaft is driven by the cutter engine by means of two steel sprocket 

 chains, at a rate of about eight revolutions per minute. 



The floating discharge pipe is 1000 ft. long with the usual rubber 

 couplings at intervals of 50 ft. There are pontoon floats on each 

 side of this pipe U-shaped in section, with the flat side closed, and 

 they sustain the pipes in yokes which are firmly attached to the 

 floats. There is a baffle plate at the end of the pipe line. The dredge 

 is provided with sixteen hydraulic piles, six of which are 10 in. in 

 diameter and 38 ft. long, and ten are 6 in. in diameter and 25 ft. 

 long. 



This dredge was constructed under contract with the New York 

 Dredging Co., which sublet the construction of different parts to 

 various manufacturers and builders of machinery. The contract 

 price for this dredge was $124,940. The maximum efficiency of 

 this dredge was found to be 3212 cu.yds. of sand per hour while 

 the minimum was 928 cu.yds. per hour. 



Radial Feeding. The last group of the hydraulic dredges used 

 in the channel and river improvements are those with radial feeding 

 and are illustrated here by the description of the dredge " King 

 Edward VII," slightly condensed from a paper by Mr. A. W. 

 Robinson, delivered before the Canadian Society of Civil Engineers. 



The dredge "King Edward VII." is anchored by spuds and 

 has a radial feed, the cutter describing an arc of a circle about the 



