154 
issued by the Secretary of State for the Home Department, 
this subject occupies a distinct head. But the more care- 
fully and repeatedly I peruse these reports, or converse 
with practical men on this part of the subject, the more I 
find discrepancies, amounting almost to confusion, as to 
what is now attempted, what is now accomplished, or what 
can at any time hereafter be hoped for. And the difference 
in the accounts on this head does not appear to depend on 
real differences between the mines themselves, so much as 
on variety of belief, or of modes of expressing belief, as 
to what now takes place. On the whole, the following 
expressions seem to convey the general opinion — " Sweeping 
the outskirts of one or two gobs."* " Coursing by the 
side" of the goaf.f " Passing round it."{ " This current 
takes its way sluggishly through the lower parts of the 
goaf, or moves round the outside of it."§ " All that oozes 
from it into the workings is removed by the air courses."|| 
But if there be any truth in the description given by 
Faraday and Lyall, of the space above a goaf as an 
inverted basin of inflammable mixture, whatever difficulties 
may attend their plan, or any other, for its separate ven- 
tilation, only on effecting this depends our deliverance 
from the greatest danger of all. Many passages in these 
reports, too long to quote, confirm the accuracy of their 
description, and I might say of my own. Their statements 
are not matter of opinion, but of the most undeniable cal- 
culation, as to many thousand cubic feet of explosive 
mixture issuing at one spot, upon a sinking of the barometer, 
of only one-tenth of an inch, or a fall of roof, lowering the 
upper edge of the goaf basin only three inches. They under- 
state their case, for they suppose only one-tenth. The fall 
* Coppull, p. 48. t Oaks, p. 57. J Oaks, p. 57. 
§ Farady and Lyall, Phil. Mag., p. 23. || P. 57. 
