XX. W. E. COOK. 
TESTS OF VOIDS IN BLUESTONE AND SANDSTONE. 
1. Water in 14 inch bluestone = 44°07. 
2.) 5, 3, 2anch sandstones. 3501s 
hy 5» 95 mixture, 80% 2 inch sandstone and 20% 14 inch 
bluestone = 35°83*). 
AP ie atc 8 », 20% 2 inch sandstone and 80% 1% inch 
bluestone = 41°3%, 
ae, ah ae os < 60% 2 inch sandstone and 40% 14 inch 
bluestone = 37°24%, 
BH fk ge a 407> 2 inch sandstone and 60% 14 inch 
bluestone = 38°48%. 
(ee <* 50)» 2 inch sandstone and 50” 14 inch 
bluestone = 36°49). 
8. Sand in 2 inch sandstone, 33°67%. 
9. ,, 14 inch bluestone, 36°31%. 
10. ,, 50% 2in. sandstone & 50% 14 in. bluestone, 32°14%. 
11. Water in sand used, 33°1%). 
Perhaps it will not be out of place to quote an article by 
Lieutenant Sankey, published in ‘‘ Mngineering,’’ 1st Sept., — 
1905, on the subject of voids in mixtures and the true 
proportions necessary to produce the best results, apart 
from the quality of the materials. 
LIEUTENANT ©. HK. P. SANKEY, R.E. 
** Hngineering,’’ Ist Sept., 1905. 
Lieutenant Sankey proposes that the specification for 
concrete might be worded somewhat as follows :— 
‘“The percentage of voids in the selected aggregate is 
to be measured, and sand and cement are to be added to 
make a sufficient cement mortar of the quality x sand 
to 1 of cement, to fillthe voids, + 20 percent. Thus the 
procedure before starting to make concrete would be as 
follows :— | 
1. Settle upon the aggregate to be employed, both as 
to its nature and its gauge, 
