108 3Ir. F. A. Abd [April 2S, 



any explosions haTe occurred of whicli the destructive efiects, so far 

 as bnminff and production of ihe fatal after-damp are concerned, 

 hxve not been more or less coneiderablv increased tkrousli the 

 agency of the coal dnst raised by the explosion, and that the 

 latter has been in Terr manv cases instnmiental in caTisin2 the 

 bnming effects of the explosion to spread over great areas, and to 

 reach to workings which, in the absence of dust, would have escaped 

 the visitation. Even of late years, long since the observations of 

 Faraday and Lyell have been confirmed and extended, mining 

 engineers and others immediately connected with the working of coal- 

 mines have been very prone to ascribe explosions, which did not admit 

 of satisfactory expLination by an accidental failure of ventilation or 

 other evident causes, to the sudden disengagement or outbursts of fire- 

 damp, such as are. in fiery coal s<:^ams, of no uncc»mmon occurrence, and 

 sometimes verv serious in their masnitude and long continuance, and 

 to charge such sudden escapes of gas into some part of the mine- 

 workings with the whole extent of the disaster, rather than to credit 

 coal dust with any important share in the origination or even in the 

 extension of the explosion. In many instances the occurrence of such 

 outbursts, following upon falls of roofs or the firing of shots, or the 

 rapid disengagement of fire-damp from coal or goaves, consequent 

 upon suiden changes in atmospheric pressure, have been clearly 

 proved to have preceied disastrous explosions ; in others, however, the 

 conclusion that an explosion has been connected with the occurrence 

 Off a sadden disengagement of gas in considerable volume, has been 

 based upon assimiptions or conjectures, more or less admissible, or 

 upon evidence of doubtful nature collected after the explosion (as in 

 the case of the recent explosion at Seaham Collieries). Under any 

 such circumstance, however, it is, to say the least, extremely difficult 

 to realise how sufficient gas to produce an explosive atmosphere can 

 be conveyed, even by the most powerful ventilating currents which 

 can circulate in mines, from, the seat of such a sudden outburst to far 

 distant portions of the mine to which the actual explosion is proved 

 to have extended, within the period which is known, or believed, to 

 have intervened between the first disengagement of the gas and the 

 firing of the expdosive atmosphere produced thereby in the ricintty of 

 the outburst, bv the firing of a shot, bv a defective lamp, or bv other 

 means of ignition. On the other hand, the character of the effects 

 which in manv instances have been produc-ed by the explosion ; the 

 evidences of severe burning such as could not be produced by the 

 rapid explosion of a gas mixture only, and the deposition of partially 

 burned or coked dust in very distant and distinct parts of the mine- 

 workings, leave no room for doubt that c-oal dust has played a more 

 - int part in almost all the explosions which have been of 

 i^v .to investigation. Further, it must be conceded that 



in - =. coal dust wotild indeed appear to have been the 



cLi.i „. of destruction, 



T . .__ ^ ; it has not been difficult, as will have been seen from 



