.11! WATER SUPPLY. TO SYDNEY. BY QBAYITATLON. 



of such iron mains per week, if required. Should this system of 

 water supply be gone into, I would advocate the adoption of 

 stop-valves at every two miles, so as never to make it necessary 

 to empty more than that length of maius to get at possible repairs. 

 I would also advocate the use of self-acting air-valves at the apex 

 of all bends in the pipes, so as extract any air that might impede 

 the free flowing of the waters, and also by this ingenious principle 

 to introduce air into the pipes when required to prevent concus- 

 sions and collapses by partial vacuums created when the waters 

 may be shut off anywhere along the mains. For interesting 

 particulars of these important self-acting air-valves I refer you 

 to the Engineer of the 3rd of April, 1874, in which the new 

 waterworks in wrought-iron mains for Virginia City and Gold 

 Hill are fully described. 



On this part of the work I would desire to point out that my 

 proposed overground mains on sleepers would pass through an 

 entirely uninhabited and waterless country along the crest of the 

 dividing range which separates the watersheds of the AVaranora 

 and the Port Hacking Creek waters. The effect of this would 

 be that such aqueduct could be tapped anywhere along the line 

 to supply reservoirs for the reclamation of large tracts of 

 Government and of private lands, which would be almost in sight 

 of the proposed Illawarra "Railway route ; and thus this water 

 conduit for Sydney would go hand in hand with such railway to 

 form extensive additional suburbs to the city — and thereby tend 

 considerably to recoup the Government in the outlays for such 

 national works, whilst at the same time the immense water power 

 that would be available for leasing would alone go very far to- 

 wards paying the interest on the capital to be invested in the 

 X3roposed high-gravitation water- scheme for the supply of Sydney. 



I must not pass over this part of the proposed water conduit 

 by the wrought-iron mains, without informing you that for some 

 five or six miles along the gradual deflection north of the Bottle 

 Forest Road, and, at about the centre of it from George's River to 

 Madden's Plains, the surface of the country is covered with pon- 

 derous and rich clay ironstone ore, which overlies the upper seam 

 of coal at some 500 to GOO feet. Here, then, we should have at 

 our command another of our biggest elements of future wealth, 

 when the Illawarra Railway should pass close by to unite coal, 

 iron ore, and water for one common cause to render that now 

 untenanted country available for future industries. 



And uoav I must crave your forbearance for a divergence from 

 the main subject, to express my thoughts for similar advantages 

 which could be made available in another direction of these pro- 

 posed waterworks. During my late surveys, I saw with what 

 facility the waterless town of Wollongong might be supplied with 

 pure water, to any extent that might be required, by means of 



