THE METROPOLITAN COLLIERY. Io3 



centre heading is used for the main haulage, while the other- 

 two intakes are for travelling roads. Cross-headings are 

 started about every quarter of a mile, or 440 yards. 



The AVelsh-bord system of extracting the coal was adopted 

 for the sake of better ventilation, but where the roof is 

 bad it is found advantageous to modify this. On account of 

 the depth at which the coal is found, and character of roof, 

 stronger props than usual are required, the minimum size be 

 ing seven inches in diameter, and on account of the large 

 amount of gas present, more air is required for ventilation 

 purposes, which are factors that had to be taken into consider 

 ation. The Welsh-bords are made ten yards wide, about 200 

 yards long, and have a pillar 50 yards w r ide between them. In 





Fig. 87. Opening Out of Bord. 



the ordinary pillar and bord, any waste is thrown on both 

 sides, while a roadway is kept open in the middle: with the 

 AVelsh-bord system, the waste is stacked in the middle, and a 

 roadway left in either side. When starting a bord off a heading, 

 two passages are commenced, each four yards wide, and about 

 ten yards long, leaving a pillar eight yards in width between 

 them: one of these passages is continued straight on (Fig. 87), 

 the other off-sets towards the first : they are then carried on to- 

 gether for the full width of the bord. When extracting the 

 pillar it is attacked from one or both bords, in strips 10 to 20 

 yards wide (Fig. 88), a roadway and pair of men working 

 <every five yards of width. One of the roadways in each bord 

 is abandoned for hauling purposes, whichever happens to be 

 in the worst condition, but it may still be used for ventilation 

 or inspection purposes, unless the roof proves too costly tc 



