475 



f 



to almost any distance, as the volume of fresh air introduced 

 will be adequate to dilute and carry off all the carburetted 

 hydrogen gas that might exude from the strata, so that 

 it would be impossible for the mixture ever to reach an ex- 

 plosive point ; for being carried off by such shafts S S, and 

 air-course W, it would not take more than ten to fifteen 

 minutes before being returned at the surface of the upcast 

 shaft or compartment, even in the most extensive mines. 



At present the air is traversing the works in currents and 

 counter-currents, to the extent of from thirty to seventy 

 miles, before being returned at the surface of the upcast 

 shaft ; which, at the ordinary rate the air travels, will take 

 from ten to fifteen hours in performing its course, but leaving 

 too often a great portion that it never reaches at all, as is 

 ascertained in almost every instance where an explosion takes 

 place. Besides, in the present system, there is no security 

 for the workmen where even a partial explosion takes place, 

 which is often the case from blowers, or the sudden fall of a 

 portion of the roof, and attended with the most disastrous 

 consequences in the destruction of life and property; — for 

 instance, the Haswell explosion, the Darley Main Colliery, 

 where six lives were lost ; the Oaks or Ardsley, where the 

 late dreadful calamity occurred ; the Jarrem, and indeed in 

 almost all other explosions which have taken place. When 

 it is considered that dependence is placed on trap-doors, Sec, 

 for the current reaching the extremity of the mine, the con- 

 sequence of the slightest interruption of the gateways may 

 easily be imagined, and, as is evident, ventilation is deranged; 

 and the air that should have been pure has reached the point 

 of explosion, by having in its course come in contact with 

 the accumulated gas. In such cases the unsuspecting work- 

 men in different parts of the mine are not aware of their 

 danger, but soon feel the effects, which are often fatal, even 

 from a partial explosion. 



It is a well-known fact, that from the effect of the back 



