404 



Mr. W. Galloway. 



Position 

 on the 

 plan. 



1 



2 



2a 



3 



4 



5 

 6 

 7 

 8 



8a 

 8b 



Description of the Sample. 



Penygraig coal 



Dust from the floor of the main heading. . . . 



Residue after sifting out 2 through muslin. . 



Coked coal-dust from a prop at the face 



Exceedingly light, hollow, brittle vesicles of 

 a black shining substance found adhering 

 as a thin skin to the roof oyer the whole 

 shaded space at (4). The vesicles were 

 thickly studded all over the same space, 

 and hung down from the roof, like pen- 

 dants, i to f inch long 



Dust brushed from a prop r no coked crusts 

 near . , 



Dust brushed from a ledge of rock : no coke 

 near 



Dust brushed from large stones on the floor : 

 no coked crusts near 



Shale constituting the roof of the seam 



Brittle shale that falls with the eoal, varying 

 in thickness from | inch to 3 inches 



Shale constituting the floor of the seam 



Moisture 

 and volatile 

 matter. 



18-66 

 17 -67 

 18-91 

 15 -29 



18-31 



15 '67 



14-94 



14 *45 

 8-46 



10-65 

 10-14 



Ash. 



2-05 

 22-20 

 31 -10 



6-61 



6-00 



23 -94 



25 -60 



29-67 

 92-56 



77 -08 

 82 -57 



The small black single-headed arrows show the direction in which 

 the deposits of coked coal-dust were thrown against the objects to 

 which they were found adhering. The double-headed arrows show 

 that it had been thrown against the same objects from two sides, 

 probably first from one side and then from the other. It should be 

 carefully noted that, as a rule, the arrows point away from the solid 

 ground, and consequently in a direction contrary to that in which the 

 blast must of necessity have travelled in passing through or into 

 every working place in the colliery, except the one in which the 

 explosion originated. It must, therefore, have been deposited during 

 the retrograde movement of the air, and this corresponds to the observa- 

 tion I had previously made at Llan Colliery in regard to the same 

 phenomenon (" Proc. Roy. Soc," vol 24, p. 359). If these deposits 

 were to be found everywhere in the workings, and if the currents 

 which produced them were not liable to baffling and reversal from 

 local circumstances, it is obvious that the arrows showing the direc- 

 tion in which they had been thrown would nearly all point backwards 

 to the spot at which the explosion had originated. Although differences 

 of opinion were expressed as to the causes of the explosion in the case 

 before us, it was admitted on all hands that it had probably originated 

 somewhere in the neighbourhood of the point o. 



Lastly, although the existence of accumulations of explosive gas 

 appears to have been almost unknown in the mine, there could be no 

 doubt that a very large amount of fire-damp was being constantly 



