66 Bemarks on the Report of the Water Commission. 



scarcely any appreciable change in the river level at Sans Souci. 

 A dam across the mouth would alter the present conditions for 

 free discharge, but there is no impossibility in making the weir 

 capable of discharging with equal freedom all the flood waters. 

 And in this connection it must be borne in mind that water 

 passing over the weir would have a fall varying from 1 foot to 7, 

 and would get away with a proportional velocity. 



Premising, therefore, that after the dam is completed the water 

 will never go over it, we repeat ihe question — will a dam of the 

 proposed construction stand ? The breakwater at Plymouth, the 

 dyke at Cherbourg, and the stone embankments that have been 

 constructed at Portland, Holyhead, and other places, furnish 

 familiar examples of the durability of such works. In all these 

 places they have been found to stand the concussion of heavy 

 waves. A rubble bank at George's River would be exposed to 

 no such trial. The site I have pointe i out is well within the 

 estuary, and sheltered from the direct action of the sea. During 

 its construction it would have to withstand the inflow and outflow 

 of the water caused by the rise and tall of the tide and the river 

 current, and, after its completion, would have to withstand the 

 pressure of the water against it. It can scarcely be denied that 

 a stone embankment may be constructed capable of resisting this 

 pressure. There is an unlimited quantity of material available, 

 and the breadth of the dam, both at the base and at the surface, 

 may be adjusted so as to furnish the required resistance. 



Colonel R. Baird Smith, in his work on Italian irrigation refers 

 to several dams in the Italian rivers made of immense blocks of 

 stone of irregular forms, supported by piles and woodwork frames, 

 and some of these dams have been in existence for centuries. 

 The rivers being fed by Alpine torrents, the impact of the water 

 is at times very severe, and many early works were carried away. 

 The timber has been added to bind the structure together, but a 

 dam at G-eorge's River would not have to stand the same sort of 

 blow, and timber, therefore, would be better away, as tending to 

 increase the porosity of the dam rather than otherwise. In some 

 localities banks of sea shingle have been found to make a good 

 barrier against the rise of the tide, and in many works carried 

 out in England for reclaiming low lands from the sea, banks of 

 rubble stone have been found to possess the requisite strength. 

 A stone breakwater, however, is only a part of the proposed dam. 

 It is, if I may so express myself, only the core of it. In tipping 

 in the stone it would be accompanied by a sufiiciency of tenacious 

 soil. There is close by in Wooloware Bay, an extensive deposit 

 of very sticky mud, which could be easily dug or dredged up and 

 dropped on the line of the stones, and a good coating of the same 

 material could be thrown down on the sides of the dam after it 



