492 



Mr. W. Galloway. 



that heating the air to a temperature of 70° or 80° Fahr. makes any 

 difference in the result, so that I have discontinued to do so in the 

 more recent experiments. 



With this apparatus, as with the smaller one described in my pre- 

 vious paper, of which it is a copy, the inertia and frictional resistance 

 of the air filling the gallery appears to be a factor of considerable 

 importance. For instance, if the whole of the sections are closed, 

 making the gallery continuous throughout its whole length of 126 

 feet, the flame of the coal-dust does not reach further than 50 or 60 

 feet from the origin ; but if the sides of the fourth and fifth sections 

 are open, making the closed portion only 54 feet long, and leaving 

 36 feet with only three sides, the flame will, as a rule, be 70 feet and 

 sometimes 80 and 90 feet long. The flame of the coal-dust appears to 

 be self-supporting in pure air, but it cannot keep up the disturbance 

 necessary to supply itself with fuel on this small scale, and, conse- 

 quently, it cannot get much beyond the point to which the more 

 energetic action, of the fire-damp explosion has extended. I will not 

 pursue this subject further at present, as it is my intention to continue 

 the experiments, and I hope to have another opportunity of stating 

 the results. 



Three great colliery explosions took place during the year 1880, 

 namely, Risca on the 15th of July, with a loss of 120 lives; Seaham 

 on the 8th of September, with a loss of 164 lives ; and Penygraig on 

 the 10th of December, with a loss of 101 lives. For the purpose of 

 the present paper I visited Bisca Colliery on the 24th of October, and 

 Seaham Colliery on the 24th of November of the same year. I had 

 also an excellent opportunity of acquiring an intimate knowledge of 

 the details of Penygraig explosion, having been* entrusted with the 

 direction of the exploring operations, and having visited the workings 

 twice within the first twenty-four hours after its occurrence, and 

 several times at a later period. The workings of each of these mines 

 were dry, and their roadways were covered with dry coal-dust, from 

 the faces at which the coal was worked to the bottom of the upcast 

 and downcast shafts ; but, with the exception of making this general 

 remark regarding them, I do not propose, in this place, further to 

 refer to the Eisca or Seaham explosions. 



At Penygraig Colliery I made three principal sets of observations 

 which have not, I believe, been made in any previous case of the kind, 

 and they appear to throw a considerable amount of light on the nature 

 of the accident. They were as follows : — 



1. The flame of the explosion had passed through or penetrated into 

 every part of the workings with the exception of one wet heading d 

 (see the accompanying plan) at the bottom of the downcast shaft. 



* It should be mentioned in this place that I had no connexion with or know- 

 ledge of Penygraig Colliery before the explosion took place. 



