410 



3. From a low state of the barometer. Mr. Buddie stated 

 that accidents from fire damp always occur with a low baro- 

 meter. In the Haswell High Meadow goaf of thirteen 

 acres, supposing the area above not to have tumbled in, 

 and the whole coal space empty, a fall of of i^^^ 

 in the barometer would have forced out 7.550 cubic feet 

 of gas below the edge of the goaf. Again, suppose that 

 the ground above had fallen in so as to leave the air space 

 in the goaf not more than one-quarter of the volume of the 

 coal removed, a fall of of an inch would still permit 1.887 

 cubic feet to issue forth. Hence the goaf, in connection with 

 barometric changes, ought to be carefully attended to. 



The method of working the coal so as to " leave the 

 air (gas) dead," is now much pursued in Yorkshire. It 

 consists in the admission of as little atmospheric air as 

 possible into the goaf, and of confining it to the faces of 

 the coal, and other parts of the mine where the men are 

 working. The goaf is made to follow immediately upon 

 the heels of the workmen, and all the slits or inlets into it 

 are immediately walled up, so as to exclude the entrance of 

 air. The principle upon which this plan is accounted to be 

 safe is this : — That fire-damp will not explode without a 

 certain admixture of atmospheric air, as before stated ; so 

 that a candle may be placed inside of a gasometer, and it 

 will immediately be extinguished ; and it is said that streamers 

 of gas issuing from goafs thus conducted into the air-passages 

 will readily ignite, but not explode the goaf itself. 



If the fire-damp were not an elastic fluid, and did not 

 expand from the causes before detailed, and could always 

 be restrained within the limits of the goaf, then this plan 

 would be perfectly safe. But, as occurred at the gas works 

 at Barnsley, in repairing a drain near the gasometer, owing, 

 perhaps, to a low barometric pressure, the gas becoming more 

 mixed, ignited the great mass, blew up the place and the man 



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