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accidental. But though improvements in many places have 
been adopted in respect to the construction of the furnace, and 
conveying the return air out of the up-cast shaft, we fear many 
cling to established practices with a tenacity worthy of a better 
cause. Yet this is not all that is required. The method of 
working coal mines, and especially the one adopted and in 
use in many collieries now working the Barnsley Thick Coal 
is another part of the wretched, dangerous, and imperfect 
system. We think, as we have already stated, that the plan 
on which collieries are laid out, influences the ventilation 
materially. On that account the method in question merits 
all that can be said against it, and no terms are capable of 
sufficiently condemning the plan or mode of working that 
has hitherto prevailed on what is called the following up 
benk principle ; and I should hold that no mine where gas 
is generated to any extent and worked on this system, is, or 
can be made, safe and secure against explosion. I have 
had full proof of what I here assert in my own experience, 
and I come to this conclusion for the following reasons : 
the benks, or wide-works are commenced from the benk 
level so called, and when an obstruction takes place at the 
working face, or in any of the roads, which is frequently the 
case, as I have seen the air course so obstructed, it prevents 
a free passage, and in many instances almost suspends the 
ventilation over perhaps one half of the workings of the 
mine ; and, no matter what vigilance and care is exercised, 
these obstructions do and will occur from causes over which 
there is no control. On this ground it is essential that 
these emergencies should be met, and in all cases there must 
be a provision that if an obstruction occurs in one part of 
the workings of a mine that the course of the air in the 
full current may be maintained in every other part of 
the workings. Another of the evils of this system is the 
number of trap-doors, which ought — not only from safe and 
