LX. 



C. W. DARLEY. 



In this instance about 45% of plum stone was worked in with 

 the concrete. 



Attached is a statement of eight curved dams designed, seven 

 of which are complete, the eighth, namely that for the Wollongong 

 Water Supply, is just about to be constructed. The leading 

 dimension and capacity are given in each case as well as the nature, 

 specific gravity, and weight per cubic foot of the stone used in the 

 concrete. 



The following table gives particulars of the curved dams constructed to date, 

 also the weight of stone used in the concrete, and capacity of reservoir. 



Name. 



Greatest 

 Height. 



Ft. In. 



Length 

 in feet. 



Radius 

 iu feet. 



Nature of rock. 



Specific 

 gravity. 



Weight in 

 pounds per 

 cubic foot. 



SB a 



Capacity 



in million 



gallons. 



Lithgow 



35 



178 



100 



sandstone ... 



2-34 



146 



10 



15 



Parkes 



33 



540 



300 



granite 



275 



17H 



24 



115 



Cootamundra 



45 6 



500 



250 



diorite 



(2-C9 

 J 266 



168 I 

 166 f 



169 



20 



1365 



Tarn worth ... 



61 5 



443 



250 



granite 



2-71 



20 



50 



Picton 



# 28 



112 



120 



sandstone ... 



2-36 



147 



12 



14 



Wellington... 



48 



350 



150 



conglomerate 



2-67 



166£ 



20 



30 



Mudgee 



50 



498 



253 



altered slate 



2-69 



168 



20 



42 



Wollongong 



42 



528 



200 



basalt 







20. 



168 



* Designed to be raised a further 15 ft. hereafter if necessary, making 43 ft. iu all. 



Drawing No. 1 shews the plan of a curved dam and three 

 sections of dams constructed, section No. 3 being the type now 

 mostly adopted and recommended. 



Drawing No. 2 illustrates the method of timbering as described 

 in the paper. 



Drawing No. 3 shews a section of the Bear Valley Dam erected 

 in California, U.S.A. This is a somewhat remarkable section, 

 having an apparently very heavy foundation and an almost parallel 

 wall on top— in this case the lower portion of the dam must be 

 subjected to a compression of about 43 tons per square foot. I 

 have drawn on in dotted lines the section of dam adopted in the 

 State for sake of comparison. 



