112 WATKK SUPPLY TO SJTDNEI BI 0BA.VITATION. 



and it would yield proportionably far more water power ; the se- 

 curity, however, for a constant supply to the city and suburbs 

 would not be so great as by duplicate smaller mains of greater 

 expense. 



"Here it may be mentioned as evidence of the value of high 

 gravitation, that if the full force of the water by only one 2 1-inrh 

 main with 1,000 feet "head," and with even 30 miles of friction 

 and delivery, was brought into the city itself, the force that would 

 be available there by its delivery of 9,524,430 gallons daily would 

 be no less than 2,002 horse-power. 



" By the low delivery plan from Port Hacking Creek one large 

 main of 36-inch diameter would not deliver more than 5,417,353 

 gallons daily into the Crown-street reservoir, and would only 

 yield the insignificant hydraulic force equal to 38£ permanent 

 horse-power. 



"These comparisons favour the having one 21-inch main to 

 begin with, and of laying down on the same line a second main of 

 the same size, as a precaution against accidents, in which case 

 such second main would be available for a double supply 

 (10,000,000 daily) when the city might require more water and 

 more hydraulic force for industrial purposes at Petersham, 

 "Waverley, and in Sydney. 



" The large extra supply for such purposes could be insured 

 by simply raising the proposed Loddon dam 20 feet higher, and 

 by continuing the supply aqueduct to the western slopes of Bulli, 

 "Wonona, and Mount Kiera for some 5 miles further than already 

 projected." — N.B. — See note at foot of section of storm dam. 



The water-power notes on the face of the map will be suffic- 

 iently chronicled in that form; but as I feared to crowd in too 

 much matter upon the map, I would desire to attach to this paper 

 one more very interesting and important note, to show the 

 practical effect of sending down waters to "Waverley, Petersham, 

 and Sydney by only one 24-inch main. 



The water which would be delivered at Waverley, Petersham, 

 and Sydney by one 24-inch main, branching off at Cook's River 

 into other pipes for Petersham and Waverley, would be, giving 

 Sydney 2,000,000 gallons daily for fire-mains, as follows : — 



Waverley ... 3,300,132 gallons daily ) p g, nev indipectl „ 

 Petersham ... 3,740,150 ditto j * or Sydney mttirectiy. 



Sydney ... 2,000,000 ditto for Sydney direct. 



9,040,282 



