110 Mr.F.A.Ahel [April 28, 



dust and air in the complete absence of fire-damp, or whether, lastly, 

 only the very limited concession be made that coal dust will add to 

 the extent, and increase the burning effect, of a fire-damp explosion ; 

 in any case, the existence of dust in abundance, and in a dry state, in 

 coal-mine workings, must be recognised as a source of danger not 

 greatly inferior to that caused by local accumulations, or the acci- 

 dental liberation, of fire-damp. The possibility of dealing with this 

 source of danger should therefore be as much an object of earnest 

 work as has been the improvement of ventilating arrangements for 

 mines. 



It being generally impracticable effectually to deal, by actual 

 removal, with the continual accumulation of dust in mine-workings, 

 the only available method of diminishing the dangers arising from its 

 constant production appears to be that of maintaining the fioor in the 

 roads, &c., in a damp condition by efficient watering arrangements, 

 almost continually applied. The high temperature of the mine, in 

 many instances, must often render this a difficult and costly process, 

 on account of the rapidity with which the water wdll evaporate ; 

 hence attempts have been made to apply hygroscopic substances (such 

 as calcium chloride, sea-salt, or rock-salt) in conjunction with water, 

 or to use brine, with a view to retard its evaporation, and some 

 successful results appear to have recently attended their aj)plication 

 in several districts. In some instances, with improved appliances , 

 for the uniform and periodical distribution of sufficient water, the 

 maintenance of mine-roads in a sufficiently damp condition to prevent 

 dust from being raised in any considerable quantity appears to have 

 been accomplished with fair success ; there are, however, localities 

 where it is almost impracticable to maintain the floor of the roads in 

 a damp condition, in consequence of the great increase thereby of the 

 tendency to their being gradually raised by the pressure to which 

 they are subject. 



Aj)art from the effects of dust in augmenting the disastrous results 

 of such fire-damp explosions as may arise from the existence of a 

 defective, or an open safety lamj) in the vicinity of an accumulation 

 of gas, or of a locality where a sudden outburst of gas occurs, the 

 blasting of coal or of rock, in those parts of a mine where fire-damp 

 may exist, if even only in very small quantities, constitutes the chief 

 source of accidents in which coal dust may have played an important 

 share. There is no doubt, therefore, that the elaboration of really 

 safe methods of getting coal in places where blasting by powder is 

 now resorted to, and of removing the harder rock in the working of 

 drifts where fire-damp may exist, will most importantly contribute 

 towards the diminution of danger arising from the accumulation of 

 dust in mines. The substitution of efficient coal-cutting machines 

 for blasting may to some extent supplant the use of pow^dcr, and the 

 employment of compressed air as an agent for bringing dowTi coal or 

 rock has been made the subject of ingenious contrivances, which 

 appear, however, as yet, to labour under some disadvantages in regard 



