Or 
— 
PROCEEDINGS .OF SECTION H. 3 
Biurstone (Malmsbury, Victoria). 
The sample was rather much honeycombed, and _ conse- 
quently shows a large soakage of water. The cube only stood 
4.87 tons per square inch, which, when compared with some 
of the sandstone tests, dass not seem good for one of the 
igneous rocks. 
TABLE SHOWING PERCENTAGE OF WATER ABSORPTION AND CRUSHING 
STRENGTH OF SOME WELL-KNOWN AUSTRALIAN BUILDING STONES. 
f : j\GonAa 
; Sizeof | Weight |e. (eam 
a ~ SEs) hes z 
| | in. in. in fs oz. dr. A*< a= 3 
1 | Granite .., Harcourt, Vic. ...| 3x3x3 [2 910] 300} — 
2 ce ..| Moruya, N.S.W....) 3x3x3 | 212138 418 | 6.97 
3 | Syenite ...| Gabo Island, Vic. | 2g x 3x 23; 2 1 0] Trace | 11.20 
4 | “ ..| Bowral, N.S.W....| 3x3x3 | 214 8 403 | 5.69 
» | Bluestone ..| Malmsbury, Vic...) 3x3x3 | 2 515] 1.1538 | 4.87 
6) a ...| Footscray, Vic. ..|3x3x3 | 211 0 043 | — 
c| / Waverley ... oxox oy, | a A. Bh. rote meee 
8 | {| Pyrmont |3x3x3 | 2 412] 3.2381 1 3.19 
a | Hawkesbury .. 3x 3x3 1-2 27 4-2) eae 
10 Sandstone - Marrickville | 3¥3x3y | 2-712) 3.773'| 1.80 
11 | Sydney, N.S.W. | | 3x3x3;|/2 7 4] 3.343 | 2.46 
12 | Parramatta N a Kees ea wo : 3.028 | 1.51 
13 | 3aX38x3°|2 4 3.466 | 1.21 
i4 | Limestone . Waurn Ponds, Vie.| 3x 22 x 2% 1 6 6 | 12.849 | — 
15 Sandstone ...| Stawell, Vic. .| 3x3x22 |} 2 412] 2.380} — 
16) . .... Barrabool Hills, V.| 3x 3x 22) 115 6) 5.468 |= 
17 | Slate ...| Mintaro,S. Aust. |6x3x1 |1138 14 641 | — 
18 | A . a x Pea BE YO 12 1S A487 | 859 
19 | + ..| Castiomname, Vie. |. 6x5= 1 | 2 cater 02 | — 
5.—CIRCULAR ARCHES. 
By Bernuarp A. Smitu, M.C.E 
[ Abstract. | 
On the assumptions— 
1. That the pressure at any point of the arch ring is normal 
to the surface and proportional to the depth from the 
“free surface” (i.¢,, the roadway) to the centre of the 
arch ring; 
2. That in the case of a partial load, uniform over the 
loaded portion, the free surface of the loaded segment 
is at a height above the roadway such that if uniformly 
filled with material of the same density as the filling 
above the arch ring the weight of the material added 
would be equal to that of the partial load, while the 
free surface of the unloaded segment is the roadway ; 
