1002 PROCEEDINGS OF SECTION H. 
for paving, and as it will expand with heat and contract with 
cold without cracking, is very suitable for a position in which it 
is subjected to great variations of temperature. But even the best 
varieties, viz., those quarried as a mineral in the Vosges and Jura 
Mountains of France, soften so much with great heat as to easily 
dent with heavy pressure, while the inferior kinds would be quite 
unreliable in such a position. Cement is free from this objection, 
but cracks instead of expanding and contracting with heat and 
cold, and so would let wetin. ‘Tiles are much used in Southern 
Europe for the same purpose, but the vaulting thereunder is thick, 
and they are constantly being kept pointed to prevent leakage. 
In India chunam roofs are common and watertight ; but the ereat 
amount of labour required in their construction would, IT fear, 
render them too costly in these colonies. An absolutely unbroken 
roof is, of course, the best ; but any means of access thereto should 
be of incombustible material, and skylights, if absolutely essential, 
should be protected by strong wire guards, kept far enough away 
from the wood and glass to prevent ignition or breakage. If, 
however, an ordinary : sloping wooden roof isfor any reason essential, 
then the regulation compulsory in Sweden for even two-storey 
buildings should be enfor ced, viz., a fireproof ceiling under it. 
I referred to this more fully in my paper on “The Fire-proofing 
of City Buildings.” 
Of equal importance with roofs are the walls and their construe- 
tion, and the chief lesson the Melbourne fire teaches us is the 
danger of long high walls unsupported by cross walls. The Sydney 
Building Act wisely provides that unsupported walls more than a 
certain length shall be greater in thickness than where cross walls 
occur. But ina great fire this is not enough, and I think it would 
be a wise thing to provide that instead of thickening the walls the 
brickwork so used should be employed in the form of cross walls 
or buttresses at specified intervals. No more space would be 
occupied, but the increase in strength would be great. If the 
limit of 216,000 cubic feet were adhered to, many businesses would 
require several warehouses to be used in connection, and hence 
openings in the walls would be necessary. These should not 
exceed (say) 6 feet in width and be protected by fire-resisting 
doors on each side of the wall, thus leaving an air-space between. 
Much attention and discussion has been devoted to the best kind 
of door—some advocating iron, others one of solid wood planks 
covered with sheet-iron, or even faced with tile or terra cotta 
slabs or asbestos fibre. But the lesson the Melbourne fire teaches 
us is, that the hangings and bearings of the door are the weak 
spots, as if they give the door falls and protection is gone ; hence 
the necessity of two doors to each opening, one on each side of the 
wall, or else the casing or effective protection of the hangings and 
bearings. Such doors being heavy are most safely hung on rollers, 
