174 



Mr. W. Galloway. 



[Mar. 17, 



March 17, 1887. 



Professor STOKES, D.C.L., President, in the Chair. 



The Presents received were laid on the table, and thanks ordered 

 for them. 



The following Papers were read : — 



I. "A Coal-dust Explosion." By W. Galloway. Communi- 

 cated by K H. Scott, M.A., F.R.S. Received February 17, 

 1887. 



(Abstract.) 



The Silksfcone pits of Altoft's Colliery, near Normanton, in York- 

 shire, in which the explosion took place, are 420 yards deep. Both 

 shafts are round, the down-cast being L2 feet and the up-cast 10 feet 

 in diameter. The thickness of the working, including a bed of soft 

 shale below the seam, used as a holing, is 4 feet 6 inches. The 

 system of working is longwall. The number of men and boys 

 employed underground in the day shift was about 350. The colliery 

 is now twenty- one years old. 



Yery little tire-damp is produced in the workings. Naked lights 

 were used by all the workmen for twenty years before February, 

 1886, yet during the whole of that period no single workman had 

 been injured by an explosion of fire-damp, great or small. 



Besides being naturally very free from fire-damp, the workings of 

 this mine were continuously swept by strong and swift currents of 

 air, produced by means of two ventilating furnaces at the bottom of 

 the up- cast shaft, amounting in the aggregate to 147,380 cubic feet 

 per minute. 



As the roof subsides upon the stowing near the faces, it is neces- 

 sary to take down a certain thickness of it in the stall roadways, in 

 order to preserve them at a workable height. For this purpose about 

 4 feet in thickness of roof was taken down by blasting in each stall 

 road, the height being thus made about 8 feet 6 inches, at a distance 

 •of 10 or 12 feet back from the face. Each stall road thus required 

 about one blasting-shot, with a charge of from two to three pounds of 

 powder to be fired in it about once every five or six days, so that 

 from seveu to ten blasting-shots were fired near the faces every day. 

 In this way the floor of each roadway became covered with small 



