630 PROCEEDINGS OP SECTION J. • 



From Pott's Hill screening tank two thirty-inch pipes will start 

 and supply the Northern, Western, and Southern suburbs, one to 

 be taken across the Parramatta River to Ryde, where there will 

 be a pumping station to lift the water to a tank on the Lane 

 Cove Road at Chatswood to supply the whole of North Shore. 

 From the Reservoir on Ryde Hill the districts of Hunter's Hill 

 and Gladesville will be supplied. 



A forty-eight inch pipe carries the water from the screening 

 chamber at Pott's Hill as far as the branch to Petersham a 

 distance of seven and a-half miles, from which point to Crown 

 Street, a distance of three miles and three-quarters, the pij)es 

 are forty-two inches in diameter. 



The Petersham Reservoir holds two millions of gallons and is 

 supplied by a forty-eight inch branch from the main one thousand 

 two hundred yards long. The time required to fill the Reservoir 

 is two and five-sixths of an hour. 



The Crown Street Reservoir, into which the forty-two inch 

 pipe discharges, is the one at present used for supplying Sydney. 

 The top water level is one hundred and forty-one feet over H. W. 

 Sydney and the bottom is one hundred and twenty -five feet. The 

 capacity of this reservoir is about three and a-quarter million 

 gallons ; it is, however, contemplated to enlarge it to about four 

 and a-half million gallons immediately. The pumps by which the 

 upper levels of the town are supplied are at Crown-street. 



The mean hydraulic gradient of the pipe from Pott's Hill is 

 1 in 2907.111, and the pipe will discharge a volume of water equal 

 to seventeen and three-quarters of a million gallons daily. 



About nine-tenths of the district of Sydney may be supplied 

 by gravitation. 



The following is a statement of the lengths of each description 

 of work : — 



Tunnels... 



Canal ... 



Across Prospect Reservoir 



"VVrought-iron flumes 8 feet and 7^ feet diameter 



„ ,, pipe 6 feet diameter ... 



Cast ,, ,, 4 feet ,, 



,, ,, ,, O2 leet ,, ... ... 



Total length of conduit in miles ... 621 



