agreed with him, and therefore what he 

 said in reply was wholly as to details. 



The Chairman said he thought the pre- 

 sent system of setting off the increased 

 value of land against the claim made by 

 the owner for compenc-ation was an equit- 

 able and intelligible one. 



The discussion was then closed. 



RESERVOIRS. 



Mr. C. B. Target read a paper on 

 'TReservoirs — Irrigation in India, and 

 Deductions with special reference to the 

 Hobart Reservoirs," illustrated by lan- 

 tern views. Speaking of waste weirs, he 

 said that ''one of the important subsi- 

 diary works 's the waste weir. I give 

 sections, showing the growth of what 

 was finally adopted as the best. These 

 weirs were originally a piece of ground 

 levelled at the end of the dam ; this was 

 found to wear away, then stone pitching 

 was used, afterwards a wall was put to 

 preserve the level, and avoid leakage 

 between the stones, then a wall at the 

 bottom to prevent the stones from slip- 

 ping. You will find this idea adopted by 

 Mr. Thwaites at the upper reservoirs. 

 Now, although these aprons were care- 

 fully made, hardly any answered ; there 

 was always settlement, so the upper wall 

 had to be made strong enough to stand 

 unsupported by the apron; so I first 

 tried rows of slabstone to bind the work 

 together, and localise settlement ; the 

 success was partial only, as extra scour 

 was created under the slabstones, so con- 

 crete was put under 2ft. deep. This, 

 although an improvement, was not suf- 

 ficient ; so I built walls above the con- 

 crete to a level with the apron, the wall 

 being coped with slabstones, the hori- 

 zontal distance of these walls being the 

 thickness of the apron multiplied by the 

 slope. This system has proved thorough- 

 ly successful, and the flow of water be- 

 ing intercepted by these walls, the re- 

 sult is that the space above gets grout- 

 ed in with silt, making the worli 



stronger year by year." Speaking of the 

 trouble at the Hobart upper rei?ervoir 

 and Mr. Thwaites's proposals, he said : 

 "The Director of Waterworks very pro- 

 perly objects to building a retaining 

 wall on a bad foundation, and proposes 

 to go down to firm ground for the foun- 

 dation, but with piers only; one of the 

 objections to t^is is, letting the water 

 further into the dam to destroy its sta- 

 bility. I consider there is no danger 

 from filling this reservoir in the state it 

 was in before the repairs were commenc- 

 ed, provided there has been no percola- 

 tion, of which I am doubtful, and that 

 the water be not suddenly lowered to 

 allow a large quantity of soil in a half- 

 sodden condition to slide down above 

 water-level ; but should it be assumed 

 that there is danger on the water side, 

 the way to prevent it is 03" not allow- 

 ing the water to alter the angle of re- 

 pose ; this is not done by the proposals 

 of Mr. Thwaites, who increases the dan- 

 ger by letting the water further into 

 the dam, and increases the weight on 

 the wet soil, so as to force out the toe 

 or overturn the proposed retaining; 

 walls. To keep out the water, I would 

 cut into the dam at the toe till fairly 

 good stuff is found, and relay the soil 

 laken out, mixed with good stuff to an 

 extra width of say 30ft., in Sin. layers, 

 well rammed with iron rammers, weigh- 

 ing not less than 181b., and not more 

 than Gin. in diameter; at one foot in 

 height cut in again for another step one 

 foot thick, and so on. The opportunity 

 of the pitching being removed m^ay be 

 taken to increase the capacity of the 

 reservoir, as w^e have seen that there 

 would be an element of danger in put- 

 ting the extra soil behind." 



Discussion on the paper was postpon- 

 ed till next monthly meeting. 



Votes of thanks were passed to Mr. 

 Moore and Mr. Target for their papers. 



The proceedings then terminated. 



