﻿£ s. 

 . 65 



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. . 20 







. 45 







. 37 10 







. 30 







. 100 







Thomson. — On Economising the Current of Large Rivers. 145 



In tills case, for the avoidance of damage by heavy floods, arrangements would 

 be made to elevate the wire cable and draw the screw and pump in-shore till 

 they had abated. 



I have already given the dimensions of a screw required to raise one sluice 

 head (ninety-five cubic feet per minute) seventy feet above the level of the 

 river, and an approximate estimate of the cost of the same would be as follows. 

 The duty required would take a single acting pump fourteen inches diameter 

 and eighteen inches stroke per second, or double acting, eleven inches diameter 

 and 14-5 inches stroke of same velocity : — 



Pump ....... 



Screw ....... 



50 fathoms of 4| inch galvanised iron wire . 

 150 feet of leather 6 inch hose, at 5s. per foot 

 150 feet of cast iron 6 inch pipes, at 4s, per foot 

 Carriage and labour (say) .... 



£297 10 

 Of course the cost would be much modified by position and the relative 

 facilities given by the state of the river, its banks, rocks, and currents. In 

 applying the large machinery, it would be advisable to choose such sites as 

 would afibrd rock foundations for the pump and geai'ings, so as to avoid the 

 necessity of supporting the same by cable or punt, and in such cases the per- 

 manent material (cast iron) might be used solely for the piping. 



As the altitude of water to be raised in many parts, especially below the 

 Teviot, does not require to be so great, of course much reduction in cost could 

 also be efiected. This remark is also particularly applicable to the service of 

 pumpLug water from river bank claims carried on below the level of the stream 

 surface, where the height to be raised is generally small. 



In many parts of the goldfields of Otago large capital has been expended 

 in bringing water to claims on the banks of the Clutha now worked out. The 

 cost of bringing in water when not available for other claims thus remains a loss. 

 Thus a great advantage is gained, under such circumstances, by the introduction 

 of the contrivance and machinery proposed, inasmuch as the plant can be 

 removed to other localities, and re-erected for new operations. 



