1816.) On the Ventilation of Coal-Mines. 295 
exploded in the higher part of the workings. It would be cruel to 
attach blame to the persons concerned in managing the colliery 
where these fatal events occurred. We are informed by a person, 
whose veracity cannot be doubted, ‘* that this mine was considered 
by the workmen a model of perfection in the purity of its air and 
orderly arrangements.” And we are informed, that, at the time 
the second explosion took place, “ the current of atmospheric air 
was so strong, that it was difficult for the workmen to keep their 
candles from being blown out by it;” if, however, under circum- 
stances so favourable, and under careful management, such fearful 
accidents occur, the irresistible conviction flashes upon the mind, 
that the existing system of ventilation must be radically defective. 
Your readers on a careful examination of the plan of the Felling 
colliery, will observe, that the workings are formed into a sort of 
double tube, which is called a double air course. ‘They will like- 
wise comprehend, that if a fall of the roof should shut up one of 
the branches of this tube near the upper end of the mine, the fire- 
damp must rapidly accumulate in the choaked passage, while the 
ventilation would proceed as usual through the other. Now, if we 
suppose this passage to be 500 yards in length from the dip to the 
rise, six feet wide, and six feet high, we shall have a magazine of 
fire-damp containing at least 2,000 cubic yards. So much for the 
quantity of fire-damp which it is possible may accumulate in mines 
conducted on the present system. 
Having thus converted the workings of a coal-mine into a tube, 
whether single, double, or treble; the next object of solicitude, 
under the present system of ventilation, is, to strengthen every 
part of this tube as much as possible. For this purpose, the lateral 
openings are strongly and entirely stopped. In the Felling colliery 
we are told, “ that the stoppings are made of brick and lime, and 
are further strengthened on each side with a wall of stone.” Now, 
if a violent explosion of fire-damp should occur in any part of this 
strongly fortified tube, the inevitable consequences must be, that if 
the stoppings stand the shock, the destructive blast. must visit every 
ramification of the workings before it can get to either of the shafts; 
and if the stoppings give way, that those persons, whom the force 
of the explosion could not therefore reach, must be cut off from 
the possibility of escape. “ But this,” says Mr. Hodgson, speak- 
ing of explosion, “ though apparently the most terrible, is not the 
most destructive effect of these subterraneous thunderings. All the 
stoppings and trap-doors of the mine being blown down by the 
violence of the concussion, and the atmospheric current being for 
a short time entirely excluded from the workings, those that sur 
vived the discharge of the fire-damp are instantly suffocated by the 
after-damp, which immediately fills up the vacuum caused by the 
explosion.” ‘The existing system is therefore placed in a dilemma 
by this part of its arrangements, from which it will not be easily 
extricated. In the mean time, while the strength of stoppings is 
considered as an essential principle in ventilation, the miner must 
