THE ROYAL ARTILLERY INSTITUTION. 
269 
sound reasoning, and ingenious experiments of Mr. W. Galloway, 
Inspector of Mines. The fact has long been known that if an explosive 
gas-mixture be driven, in a current of sufficient force, through the 
gauze of a safety-lamp at right angles to the lamp, flame may be forced 
through the meshes, and may thus ignite the explosive mixture outside 
the lamp; but Mr. Galloway conceived, and has clearly established by 
experiments in the laboratory and in coal-pits, that the sound-wave 
established by the firing of a shot (especially by the sharp explosion 
produced when the tamping is shot out of a hole) will by transmission, 
even to very considerable distances, have the effect of forcing flame 
through the meshes of the gauze of a safety-lamp, and will thus lead to 
the ignition of an explosive gas-mixture surrounding the latter. Safety- 
lamps may frequently be accidentally surrounded by (or purposely 
introduced, for purposes of inspection, into) an explosive atmosphere at 
the time that shots are fired in neighbouring workings; and the cir¬ 
cumstantial evidence collected after the occurrence of some explosions 
has undoubtedly indicated that this is the most probable explanation of 
the cause-of the accident. It is probably not to be expected that even 
in fiery coal-pits miners will forego the advantages derivable from the 
employment of gunpowder, and it appears next to impossible to enforce 
prohibitory regulations with respect to such pits ; but it may perhaps at 
any rate be hoped that the miner may be trained to a knowledge of the 
danger he incurs by the incautious use of gunpowder, although the 
persistent recklessness with which he sacrifices safety to comfort, in 
despising the use of the safety-lamp, forbids sanguine expectations in 
this direction. 
Reference has not been made to another very possible source of acci¬ 
dents, due to the employment of gunpowder for blasting purposes— 
namely, carelessness in the keeping and handling of the explosive agent 
by the men. Personal observation by the speaker of the reckless 
manner in which powder is frequently dealt with in mines, leads him 
to believe that this contributes its quota as a cause of colliery explosions. 
The accidents in collieries have their parallel in domestic life in coal- 
gas explosions, which, though at first sight of comparatively small 
importance, if judged by the loss of life and property which they occasion, 
yet merit serious consideration on account of the great frequency of 
their occurrence, and the demonstration which they almost always 
afford of ignorance or culpable carelessness. Whether occasioned by 
defective gas-fittings or by want of care in dealing with the gas-supply, 
the escape of gas in a confined space, in any but very small quantities, 
must speedily result in the production of an explosive gas-mixture, by 
the rapidity with which the gas will diffuse itself through the atmos¬ 
pheric air surrounding the point of escape. The application of flame to 
such a mixture must inevitably result in an explosion, the destructive 
effect of which is regulated by the quantity of gas escaping and the 
time which it has had to mix with the air. 
The circumstance that the admixture of even minute quantities of 
coal-gas with air can be at once detected by the unmistakable odour of 
the gas, should serve as a safeguard against accidents; unfortunately. 
