44 Mr. W. Galloway. On the [May 15, 



great explosions it was found that the flame had passed through 

 very long galleries, containing presumably nothing but pure air, and 

 of coarse dry coal-dust in a state of greater or less purity; and, 

 secondly, it was impossible to account for certain other explosions, 

 except on the supposition that they had been originated by the firing 

 of a shot in pure air in galleries containing dry coal-dust as in the 

 last case. To have proved that a mixture of air, coal-dust, and fire- 

 damp is inflammable did not appear to me fully to meet the case, and 

 it was for this reason that I made further experiments with the help 

 of a grant made to me by the Lords of Committee of Council on 

 Education at the recommendation of this Society. The results have 

 been described in some of the former papers of this series. In 

 making these experiments, and in drawing certain conclusions from 

 them, all favourable to the hypothesis referred to, I was simply 

 carrying out the details of the work then begun, and nothing 

 more. 



In former papers I referred to several great explosions which had 

 come under my own immediate observation. In particular I had 

 made a very careful and complete examination of Penygraig Colliery 

 after the explosion there in December, 1880 ("Proc. Boy. Soc.," 

 vol. 32, p. 454), when I found that the flame had penetrated into every 

 working place in the mine. The plan which accompanies No. Ill 

 paper shows that all the working places were ventilated by what was, 

 practically, a single current of air. It was, therefore, open to those 

 who attribute every great explosion to the occurrence of a sudden 

 outburst of fire-damp, and, as the annals of mining show, they con- 

 stituted a very largo majority before the appearance of my first paper 

 on coal-dust, to say that this explosion was due to the same cause. 

 For this reason I have paid particular attention to the phenomena 

 due to the explosion which occurred at Dinas Colliery on the 13th of 

 January, 1879. I do not propose to enter into the minute details of 

 this case, as I should to a large extent simply be repeating what I 

 stated about Penygraig explosion, but will confine myself to those 

 which are necessary or new. I had frequently inspected the workings 

 before the explosion, and I have done so at intervals of one month or 

 less since then, so that I have been intimately acquainted with all the 

 conditions of the mine for many years. I know also that no sudden 

 outburst of fire-damp has ever been known to take place in it. The 

 workings were naturally very dry, the temperature ranging from 75 

 to 82 F., and the floor was covered with coal-dust. Shot firing ws 

 carried on by night when the explosion happened. The damage done 

 by the explosion was very great, the workings being wrecked to sue 

 an extent as to lead to their temporary abandonment. They wei 

 re-opened after a large expenditure of time and labour, and it ws 

 only towards the end of last year that I was able to inspect the 



