XXXll ABSTRACT OF PROCEEDINGS. 



was forced through the pipes in order to fill any voids that 

 might occur between the concrete and the rock. 



The cost of these pressure tunnels, which were 14J feet 

 in diameter, was on the average 180 dollars (£36 18s. 9d.> 

 per 1 inch foot of completed tunnel. This price does not 

 include the engineering, real estate, nor administrative 

 expenses, which would increase the figures from 15 to 20%. 



In estimating the cost of the work I propose, viz., for a 

 main tunnel, 7 feet 8 inches diameter and 27*3 miles in 

 length, branch tunnel to Orown-street, 5 feet 3 inches 

 diameter and 11*55 miles in length, and a branch tunnel to 

 Ryde 5 feet 11 inches diameter and 8*3 miles in length. I 

 have provided for the works to be carried out under a 

 similar system to that adopted in New York, and the cost 

 works out as follows : — 



Main Tunnel 16 9 



Branch Tunnel to Crown-street 



Branch Tunnel to Ryde ... 

 These prices include the cost of shafts, and all other 

 expenses, including engineering. 



Mr. Oorin supplied some very interesting information 

 with reference to the comparative cost of pumping and of 

 power supply in Sydney. He proposes to provide a power 

 station at Broughton's Pass, by utilising the daily flow 

 (and in times of flood the overflow) from Cataract Reser- 

 voir and the Oordeaux Reservoir, combined by means of a 

 tunnel between them. Mr. Corin claims that the result 

 of supplying electrical energy in the manner he proposes^ 

 would be that the pumping costs (column N) of my table 

 in 1947, instead of being £641 per day would be only £239 

 per day, resulting in a saving of over £400 per day, 

 £146,000 per annum, in which case, instead of the saving 

 of £125,500 per annum in 1947, shown by the last figures 



£ s. 



d. 



16 9 



7 pe 



12 17 



7 „ 



13 14 



1 „ 



