1874.] 



Mr. W. Galloway on Safety -Lamps. 



443 



It will be seen from the data given above that shot-firing was carried 

 on in 17 of the 22 collieries at which important explosions took place 

 after the 12th of December, 1866 ; safety-lamps were certainly used in 

 12, and probably also in the 5 which are marked doubtful ; in 8 cases it 

 was ascertained that a shot had blown out the tamping at or about the 

 time of the explosion ; in 2 an empty shot-hole was found, from which the 

 tamping is supposed to have been blown ; and in 3 a shot had been fired 

 bringing down the coal or rock ; finally, at Bisca, Ferndale (1867), Hay- 

 dock (1869), Low Hall, Eenishaw Park, and Seaham, two or more explo- 

 sions appear to have taken place simultaneously in different parts of the 

 mine unconnected by a train of explosive gas. The Seaham explosion is 

 a remarkable one : a heavily charged shot was fired in pure air in one of 

 the intake-aircourses, and, according to the statement of three men who 

 survived, the explosion of firedamp followed the shot immediately ; one 

 of the men further asserted that, in several minutes more, he heard the 

 distinct report of another explosion. 



Two methods of accounting for the simultaneousness of the explosion 

 of firedamp with the .firing of the shot have been suggested in the 

 Reports of the Inspectors of Mines : one of them supposes that the fire- 

 damp is ignited directly by the shot ; the other, that the concussion of 

 the air caused by the explosion of gunpowder dislodges gas from cavities 

 in the roof and from goaves, and that this gas, passing along in the air- 

 currents, is ignited at the lamps of the workmen. In some instances, 

 when it has been known to be highly improbable that any gas existed 

 nearer to the shot-hole than 10, 20, or even 40 feet, the advocates of the 

 former hypothesis have taken it for granted that the gases issuing from 

 the shot-hole were projected through the air as far as the accumulation of 

 firedamp, retaining a sufficiently high temperature to ignite it on their 

 arrival. On the other hand, the advocates of the latter hypothesis have 

 not attempted to show how the gas, which they assumed could be dis- 

 lodged in quantity by a sound-wave and its reflections, could be ignited 



