106 WATEE SUPPLY TO SYDNEY BY GRAVITATION. 



is perfectly tight and successful, as maybe seen by my appendix 

 to the present paper. 



On reference to my map you will perceive that there is a high 

 range that divides the Loddon waters, which rim into the Cataract 

 River and then into the Nepean, from the Madden's Creek waters, 

 which run into George's River and Botany Bay. The highest 

 point of the range on Madden's Plains is 1,331 feet over the sea, 

 as proved by my survey. Prior to my late survey the elevations 

 in that district had only been determined by barometrical meas- 

 urements, and not with the proper instrument and staff. From 

 the northern side of this dividing range which separates these two 

 watersheds we can obtain further supplies for Sydney by my 

 scheme, as you ma}r perceive by looking at the map. You may 

 there observe that instead of making large dams on the Madden 

 Creek, as I had before advocated, I now propose to adopt only 

 one small storm-water dam, capable of impounding only twenty- 

 six half-acres of water at the surface, with the view of intercepting 

 the upper waters after heavy rains, and of letting off such waters 

 down the creek gradually by means of a sluice and valve, and 

 so to conduct them by steady gravitation down the creek to the 

 intake of the shaft at point E on the map, and which shaft would 

 take these Madden Plains waters down into the Loddon tunnel, 

 at a depth of about 70 feet, and then pass on with the other 

 tunnel waters into the open canal and on to the intake of the 

 wrought iron mains on the Bottle Forest Road, at an elevation of 

 1,062 feet over the sea. 



Should one storm-water dam be insufficient to arrest all freshes 

 as they come down this small watershed from Madden's Plains 

 proper, another might be made a little above the first one which 

 is marked on the map. By this arrangement, aided by the little 

 embankment at letter N, we should probably always intercept the 

 waters of Madden's Creek instead of letting any part of them pass 

 over Rice's Falls, close by, on their way to (ieorge's River and 

 Botany Bay. Here I may state that my map shows an elevation 

 of this storm dam on Madden's Creek, and that under such sketch 

 is the following note : — " It is to be understood that dams of this 

 nature (with concrete cores only) would have to be made every- 

 where along and above the southern aqueduct, where the levels 

 would admit of them. This arrangement would be with a view 

 to obtaining exceptional supplies." 



It is quite impossible, within the limits of a paper like this, to 

 enter sufficiently into the various details of my scheme, so as to 

 be clearly understood ; therefore it is that I have endeavoured to 

 make my large map almost self-explanatory of the whole project, 

 and in which I may hope to have succeeded, although at the risk 

 of being thought to have overcrowded it with matter. 



You will thus see that I have shown ways and means of supply- 



