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vault ; yet at the upper edge, a mixture of gas and air, and 

 even a highly explosive mixture, might be escaping : That 

 in mines subject more or less to fire-damp these goafs give 

 out gas into the workings by a gradual underflow in smaller 

 or larger quantities under ordinary circumstances ; and some- 

 times suddenly, and in great proportions, on extraordinary 

 occasions : That the fire at Haswell took place close to the 

 goaf of the Meadows working, the issue of gas being probably 

 caused by an extensive falling in of a considerable area to 

 the surface, and that the goaf of the High Brockley Whins 

 working increased the conflagration. 



At the Oaks Pit, near Barnsley, the explosion took place 

 from a goaf of about three acres, although the Pit has only 

 been working three years, and there are not yet excavated 

 above twelve acres. A man was working within sixteen 

 yards of this goaf known to be full of inflammable air, with 

 a naked candle ; and it appears from the evidence at the 

 inquest, that he had gone towards it with his candle, for he 

 was found dead half way between the place of working and 

 the goaf. About one-half of the persons were either burnt to 

 death, or killed by the violence of the explosion ; the other 

 half, or at least one-third, were suffocated by the after-damp 

 or carbonic acid formed from the explosive mixture. 



The explosion at Mr. Horsfall's Pit, in Worsbro'-dale, is 

 another recent example of the danger of goafs. 



Sudden irruptions of gas from goafs into the workings 

 may be produced by three causes. 



1. If the goaf cavity is full to the highest edge level, the 

 mechanical fall of the roof will drive some portion of gas or 

 mixture into the workings of the mine. 



2. As named by Mr. Buddie before the Committee of the 

 House of Commons in 1835, that gas from an upper seam 

 of coal, when the strata fall in and fill up the goaf, is often 

 emitted downwards. 



