THE 15ULLI COLLIERY. 181 



were killed by the actual explosion itself, for most of them 

 <lied while in the act of escaping from the effects of poisonous 

 gases, as indicated by the positions and conditions of the 

 corpses. The total annihilation of life was due to the small 

 area opened up in the district where the explosion took place, 

 no wastes existing wherein the force of the explosion could 

 expend itself, it being confined to the narrow strip of working 

 where the men were actually engaged. 



According to the findings of the Royal Commission which 

 was appointed to inquire into this disaster, the accident was 

 caused by an explosion of light carburetted hydrogen gas that 

 had accumulated at the face or between the face and the last 

 s fcenton of No. 2 heading, in the Hill End district, and that 

 the immediate cause of the explosion was, in all probability, 

 the flame from an overcharged shot that had apparently been 

 iired in the coal on the top of a roll in the face of No. 2 head- 

 ing: also that the explosion was intensified, and the force in- 

 creased to distant parts of the district, by the presence in the 

 mine air of coal dust in a minute state of division. 



Fire-damp was first seen in the Hill End district between 

 < eighteen months and two years prior to the explosion, having 

 been discovered when crossing a dyke in the main heading 

 incline plane, and since then it had been reported in small 

 quantities. Fire-damp is by no means uncommon in the 

 neighbourhood of dykes, where the igneous rocks often burn 

 the coal in its neighbourhood to a cinder, and in others by 

 driving off some of the volatile hydrocarbons leave behind 

 so-called natural coke. There is a good deal of both cinder 

 and natural coke at Bulli. A considerable area of the Bull! 

 Colliery is subject to "rolls." These are rises in the floor, 

 which have a greater length than breadth; individually, the 

 same roll is seldom traced for any great length, but where 

 one ends another may commence. Sometimes they occur 

 so frequently that a roll may serve as a pillar between each 

 bord. Anyhow, they seriously interfere with the laying out 

 and winning of that part of a colliery in which they occur. 

 These disturbances are solely confined to the horizon of the 

 upper or seven-foot seam ; in the four-foot seam below, these 

 irregularities have not been found. Also the roof of the 

 upper seam is slightly, if at all, affected. As a rule these 

 irregularities do not cut off the whole thickness of the coal 

 seam. The mine was ventilated by means of a furnace, 

 but this does not appear to have had anything to do with the 

 explosion. The colliery is a dry one, the atmosphere is warm, 

 and the coal is friable and easily pulverised, so that during 

 work the air becomes charged with dust. The main road 

 used to be watered, but not the headings or Avorking-places. 

 It is well known that most dust is made in the latter, where 



