490 



Mr. W. Galloway. 



" On the Influence of Coal-dust in Colliery Explosions. 

 No. III." By W. Galloway. Received May 30, Read 

 June 16, 1881 * Revised February 10, 1882. 



[Plate 4.] 



In September of last year (1880) I commenced a new series of ex- 

 periments with coal-dust with a larger apparatus than the one 

 described at p. 416, vol. 28 of the " Proceedings/' Excepting the 

 difference of scale, however, the two sets of apparatus are nearly the 

 same in construction, and they are identical as far as the experiment 

 is concerned. 



A photograph accompanying the paper, and remaining in the hands 

 of the Royal Society, represents the apparatus as it stands ready for 

 work at Llwynypia Colliery. Its principal details may be sufficiently 

 understood from a verbal description ; they are as follows : — 



A. The explosion chamber, about 6 feet long by 2 feet in diameter ; 

 lined with thin strips of wood round about its circumference ; with 

 two openings, a -and a', in its upper side, the first for admitting fire- 

 damp, the second for igniting the mixture ; a third opening nearly 

 below a for letting out the air displaced by the fire-damp is not 

 visible. Internally it is provided with a small centrifugal fan, which 

 draws the air and gas from the farther end of the cylinder through a 

 pipe 4 inches in diameter, and concentric with the cylinder, and ejects 

 it round its periphery at the nearer end, where it is situated. This 

 mixes the air and gas. The cylinder rests on a carriage with wheels, 

 and can be drawn back from or brought close up to the rectangular 

 chamber, B, to which it can be fastened by means of four bolts. 



B. The gallery, about 126 feet long by 2 feet square inside, made of 

 wood, consisting of seven pieces, each 18 feet long, placed end to end. 

 The separate pieces are hooped with iron bands, and one side of each 

 can be opened like a door 18 feet long by 2 feet 3 inches wide, with 

 horizontal hinges. The iron hoops are so arranged that they consti- 

 tute hinges, hasps, and locking-bolts for the doors at the same time. 



C. The measuring cylinder; its upper end is connected with the 

 explosion chamber, on the one hand, by means of the india-rubber 

 tube attached at the point a, and with the fire-damp pipe on the other 

 hand by means of the tube b ; its lower end is connected to the bottom 

 of the vessel D by means of the flexible pipe c ; it is provided with 

 three stop-cocks and a water-gauge. 



D. A vessel that can be raised above or lowered below the level of 

 the measuring cylinder by means of a windlass, F, with a rope passing 

 over the pulley, d, and attached to the bow at its top. 



# See Abstract, vol. 33, p. 454. 



