1016 PROCEEDINGS OF SECTION H. 
VENTILATION. 
Coal-mining has progressed in no direction more rapidly during 
the last half century than in the methods and thoroughness of 
ventilation. Instead of the 10,000 and 15,000 cubic feet of air 
per minute considered ample to ventilate a colliery in the earlier 
years of the century, it is not unusual for one fan to circulate 
400,000 cubic feet of air per minute through the airways of a 
colliery. The splendid fan of the Metropolitan Colliery in this 
country readily circulates a current of 300,000 cubic feet of air 
per minute through the workings. 
Although the above quantities are exceptional, it is to the mag- 
nificent achievements in colliery ventilation of recent years that 
must be attributed the well-established fact of a collier’s occupation 
being now one of the healthiest in the long list of industrial 
pursuits. 
Ten years ago nearly every colliery in New South Wales was 
dependent on underground furnace for ventilation ; to-day there 
are some ten fans in the Northern and three in the Southern 
district. 
Fortunately the collieries of New South Wales have hitherto 
been exceptionally free from explosive gas, and in only one colliery, 
the Metropolitan, where a highly explosive gas of a peculiar 
character is met with, has it been found necessary to use safety 
lamps continuously. No doubt when the dry and gassy coal under 
Sydney Harbour is reached, much gas will be given off, and great 
care will be necessary in its ventilation. 
The investigations carried on of late years have demonstrated 
the danger that exists, even in the absence of explosive gas, from 
the presence of dry dust, due to the attrition of coal and certain 
kinds of rock, and deposited on the floor and timbers of roadways 
when ordinary powder and many other explosives are made use of 
for blasting. That many otherwise inexplicable explosions have 
occurred from this cause is now univ ersally conceded, and the 
remedy lies, where blasting is necessary, in the use of the safest 
explosives, removal of the neighbouring dust, and _ liberal 
watering. 
Ten years ago the disastrous Bulli explosion occurred, and there 
are now few intelligent men versed in this subject who doubt that, 
‘however begun, its propagation throughout the roadways of the 
mine was due to the presence of dust. 
Inthis réswmdé of the writer’s original paper, it has been necessary, 
not only to condense, but to excise many portions, leaving only 
sufficient to indicate very briefly some of the chief features of the 
subject. 
