6-27 
prudential considerations, but in a commercial point of view — 
to be avoided, and we think it is quite possible, as we shall 
shew, to obtain efficient ventilation without this hitherto 
necessary evil, for we are forced to the conclusion, when 
trap-doors are multiplied, they become excessively dangerous, 
impede ventilation, and are also an intolerable nuisance. We 
propose to dispense with many of them. We would further 
notice the prevailing practice of bratticing in ventilating 
straight work ; not because it is dangerous in itself, but because 
of the manner in which it is generally carried out : it forms an 
obstruction intentionally, fixed by design, and it is recom- 
mended and used by men in many respects intelligent and 
clever, but what is the effect in practice ? That the passage 
through which the air travels is reduced to about one half 
its proper dimensions, and instead of a proper area being 
maintained through all the workings of the mine, and 
uniform with the levels or intake, these successive obstruc- 
tions and reductions combine to bring about results the most 
fearful, and render it absolutely impossible to supply a 
sufficient ventilation where this practice prevails ; as all 
air roads should be free as far as possible from irregularities 
and obstructions, and as large an area maintained — or, indeed, 
larger in the return than in the intake air courses, on account 
of its increased density. 
Another important feature in good ventilation is that 
there be as few communications as possible between the 
in and out going air, as these are most destructive to the 
current of air, as every door and stopping destroys the 
force of the current, more or less, through leakage. 
Having pointed out some of the evils of the existing 
system, (to enumerate them all would take up too much 
of your valuable time) in summing up, we claim a little 
indulgence if we assert that the want of sufficient air, of 
ventilating power, obstructions in air passages, bad methods 
B b b 2 
