770 EDITORIAL 



may have such a retarding effect upon the charring of the dust, as it appears 

 to have had in the room studied at Monongah, it would seem that, by an addi- 

 tion of sufficient quantities of finely powdered shale, or earth material of simi- 

 lar kind, to the coal dust, we might reasonably expect that the latter would 

 be rendered essentially non-explosive. 



Whatever may have been the immediate causes which precipitated these 

 terrible disasters, the general, underlying cause of all of them seems to have 

 been an explosive condition of the mine dusts, owing to the drying effect of 

 strong ventilation at this season of the year. The strong ventilating currents 

 were intended to dilute and remove the firedamp before it could accumulate 

 in dangerous quantities, and to furnish good air to the miners. In both of 

 these directions they were effective. But they dried the dusts, and therein 

 seems to lie the source of greatest danger in the bituminous mines of this 

 region. Simple gas explosions without the co-operation of dust could, certainly 

 in the Monongah, and probably also in the Darr and Naomi mines, occur only 

 as very localized explosions of pockets of gas, affecting only a very small por- 

 tion of the mines. General mine explosions, due to gas alone, would seem 

 impossible with the present ventilating systems of these mines in good working 

 condition. The great extent and destructiveness of these recent explosions 

 seem to have been due almost entirely to the coal dust. 



Mutual Relations of Methods of Control 

 It is obvious that a first condition in the proper control of a coal mine is 

 an effective system of ventilation, for this is the only safe remedy against the 

 dangerous accumulation of methane and other explosive gases which may 

 issue from the coal formation at unexpected times and threaten an explosion. 

 Good ventilation is even more necessary for the health of the miners. It is 

 indispensable. In the mines under investigation it appears to have been wholly 

 adequate, but the investigation seems to show that ventilation itself has its 

 dangers, and that these increase in proportion to the very effectiveness of this 

 necessary measure. During the months in which cold air is forced in large 

 quantities into warm mines, as is inevitable in the on-coming cold season 

 following the summer warmth, the mines, as we have seen, are liable to become 

 excessively dry and subject to dust explosions, even when they are fully pro- 

 tected against all serious gas explosions. Such general dust explosions may 

 start from gas explosions that would, in themselves, be comparatively unim- 

 portant, or they may spring from entirely different causes, as defective blasting. 

 The most serious problem, therefore, seems to be the development of prac- 

 tical devices by which the dangers of effective ventilation in the cool season 

 may be reduced to the lowest possible terms. The chief practical suggestion 

 of the foregoing investigation relates to this critical point of forestalling the 

 incidental danger of an adequate system of ventilation which is, in itself, an 

 absolute necessity to good mining conditions. 



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