599 
to carry their coal across each other's ground; and thus 
there would be constant quarrelling'. He thought the 
suggestion of carrying off the gas to the rise a very 
excellent one ; still there were practical difficulties regarding 
its escape, of which he thought Mr. Brakenridge was not 
aware. In his (Mr. Briggs') colliery, they found the 
straight works a very great expense ; but they were 
necessary for the comfort and safety of the men, and there- 
fore expense was a secondary consideration. No doubt, the 
best ventilation was that of the cupola fire, but there was 
danger attending it — the danger that the men would allow 
the fire to go down, and thus stop ventilation. With regard 
to the question of propping the roof, they had found the 
requirements in one of his mines the very reverse of those 
of another. In one, when they took away the props, the 
roof fell close up to the working face; but in the other, 
the roof was so hard a rock that they could work 70 yards 
by 70 without a prop. Now, the latter roof was the most 
dangerous, because when it did come it brought with it an 
immense quantity of gas, which was liable to rush upon the 
men. That was a goaf which required ventilation : whereas, 
when the roof fell close, it was not necessary to ventilate 
the goaf. With regard to the direction of the explosion, 
the ignition of foul air at the cupola fire of a mine was like 
setting fire to a train of gunpowder, for the explosion would 
extend back to the farthest extremity of the workings. 
Then there was danger in the continuous working of a mine, 
because when, as at Lund-hill, a mine was worked night 
and day, and trap-doors were being continually opened, the 
current of air was as constantly baffled, and the air of the 
mine became in an impure state. Let that go on long 
enough, and an explosion, more or less extensive, was 
inevitable, especially when the return air was carried 
through the fire. Beyond all doubt, the principle of 
