lviii. ABSTRACT OF PROCEEDINGS. 
statistics showing the advisableness of establishing such a 
system by utilising the waste waters of the Nepean River, 
These waste waters—or waters not required for the supply 
of Sydney—were shewn to be considerable, and by means 
of the existing canal could readily be applied to the soil at 
a cheap rate. Referring to masonry dams, Mr. KEELE 
doubted whether there is proper adhesion between the 
lower beds of the stones and the mortar, owing to the 
universal method of building such dams, the air being 
imprisoned beneath the stones. He showed photographs 
of the broken weir at Broughton’s Pass in confirmation of 
this. 
Messrs. F. M. GumMow, Oscar SCHULTZ (by invitation), 
and H. ©. Kent (Pres. Inst. Architects) also discussed the 
question. 
20th June, 1906. 
Mr. J. HAYDON CARDEW in the Chair. 
Mr. W. E. Cook read a paper on “The washing and 
grading of Sand for Concrete,”’ referring more particularly 
to the American experiments with unwashed sands, and 
with sand in which loam and clay are present. 
Mr. F. M. GUMMOW gave some of the results arrived at 
by him after considerable attention to the matter of grad- 
ing of sand. The washing of sand from broken sandstone 
is not only unnecessary and expensive but harmful, as all 
the small grains of silica are carried off, and all experi- 
ments shewed that pit sand should not be washed. 
Mr. A. PEAKE gave the results of numerous tests which 
Shewed that in almost every case the washed sand gave 
better results than the unwashed. 
Messrs. J. H. CARDEW, H. D. WALSH, H. DEANE, and §. H. 
BARRACLOUGH also joined in the discussion. 
