407 



has only lost, by the effects of fire damp, one man ! while in 

 the neighbouring pits in the same coal there have been lost 

 as follows : — 



Oaks Pit 72, and 3 at a former explosion. 



Messrs. HorsfalFs 6, and 3 ditto. 



Worsbro' Park 10 



Messrs. Day and Twibell's 15 

 Messrs. Hopwood's 3 at least. 



Total 112 



But, nevertheless, double board-gates are not sufficient for 

 every seam of coal, since they are in general use in nearly 

 all mines in Yorkshire, excepting the Barnsley or Thick 

 Coal. They are in use at Mr. Smithson's Colliery, near 

 Wakefield, yet not one candle is allowed to be used in that 

 pit. If a seam be full of slines,'' they may be sufficient; 

 but in several beds, the Haigh Moor especially, there is 

 much gas in the stone roof. Other coal beds have gas in 

 the cells of the coal itself ; and others again have very few 

 partings or divisions. And, therefore, separate air courses, 

 with separate roads for returning currents of air, are required, 

 just as much as several separate main drains will un water an 

 estate better than one circuitous and meandering one can 

 possibly efi'ect. 



Owing to the fire-damp being lighter in weight than 

 atmospheric air, there is a constant tendency of this gas, 

 (particularly if the coal bed rises at an acute angle,) to creep 

 along the roof to the upper and higher portions of the ex- 

 cavated mine, and thereby accumulating to form a most 

 dangerous magazine. Nearly one-half of the explosions 

 which occur are from accumulations in the goaf, either from 

 gas arising there spontaneously, or by its having drained 

 there from other parts of the mine ; and these goafs become 

 sources of great danger, because they are always ready to 

 add the contents of their reservoir to any small explosion 



