VALE OF CLWYDD COLLIERY. 109> 



pillar where the other pillars remain standing ; this protects 

 the men as they work towards the broken ground. As work 

 proceeds the roof is supported by props, with lids or cap- 

 pieces. As successive lifts are taken off the pillar, the props , 

 both in the far bord and the pillar, are knocked out with a 

 hammer, to allow the roof to fall in, taking care always to 

 keep 16 yards of roof supported between the miners and the 



Fig. 45. Diamond of L Iron. 



fallen ground. The top coal comes down easily close to the 

 props. The holing picks used are the standard double pointed 

 3^1b. tool. Sullivan's chain breast machines have now been 

 introduced into this mine. In places the headings are sup- 

 ported by old bridge rails resting on old double-headed rails r 



vvj 



Elevation. 



Plan. 

 Fig. 46. Door. 



