HISTORY OF CIVIL ENGINEERING IN NEW SOUTH WALES. 623 



Since the publication of Mr. Clarke's report an amended scheme 

 has been broufjht forward prominently by Mr. F. Gipps, C.E., the 

 merits of which have been warmly discussed in the daily papers. 

 Mr. Gipps proposed to construct a storage reservoir at Kenny Hill, 

 instead of Prospect, and to lead the water into Sydney from the 

 Kenny Hill Reservoir by means of a double line of pipes. The 

 advantages claimed by the advocates of this scheme are somewhat 

 as follows : — 1. That the proposed site at Kenny Hill, being nearer 

 to the source of supply, would shorten the length of the canals and 

 aqueducts, tfec, of sufficient capacity to convey the water to the 

 storage reservoir. 2. That, in consequence of the greater elevation 

 of Kenny Hill, a double line of pipes could be laid to a reservoir 

 situated at Waverley, having such a steep mean hydraulic gradient 

 that considerable economy would have resulted. 3. That the scheme 

 is purely a gravitation scheme, and that consequently the pumping 

 engines at Crown-street would not be required. 4. That the 

 extra head of water would be valuable for the extinction of fires, 

 and the working of hydraulic lifts and machinery. 



DKSCRIl'TION OF THE SYDNEY WATER SUPPLY. 



The present water supply of Sydney is derived from the Upper 

 Nepean, the Cordeaux, and the Cataract Rivers, at a level suffi- 

 ciently high to supply Sydney by gravitation. 



The di'ainage area comprises three hundred and fifty -four square 

 miles entirely in a sandstone country, which is at present prac- 

 tically unoccupied, and likely to remain so, since the country is 

 sterile and consequently unsuitable for agricultural and pastoral 

 pursuits. 



The rivers above referred to rise in the mountain country 

 running parallel to the coast, between the Bulli Pass and the 

 Mittagong Range, and which attains an elevation of one thousand 

 feet and upwards. The mountains present a very precipitous face 

 towards the sea, with a moi'e gentle slope landwards, they thus 

 form a barrier to intercept the rain clouds coming from tlie sea, 

 which condensing discharge their water on the extended area of 

 these landward slopes. 



A comparison of the records of rainfall near the coast, with 

 that more inland, will show the larger rainfall is deposited soon 

 after the clouds pass the summit of the range. The quality of 

 the water from such a source as the one above referred to is 

 unquestionable. There are, moreover, numerous swamps in tlie 

 upper portion of the catchment area which retain the water falling 

 upon it, preventing its rapid discharge by the rivers, and rendering 

 their flow more equable. 



These rivers, like all those in the sandstone country, have cut 

 their way into narrow gorges of a very rugged chai-acter, till their 



