74 STATISTICS OF THE COLLIERIES OF 



inches to about 10 feet; the greater proportion being between 

 3 feet and 7 feet. The dip of the beds varies from nearly 

 level to an angle of 45 degrees, and sometimes more. Work- 

 ings are in some cases carried on at the distance of 1,000 

 yards to the dip of the shaft, the produce being drawn up by 

 engines placed on the surface or in the mines. Some of the 

 mechanical arrangements for this purpose, and for the transit 

 of coal down the steep inclines, are exceedingly ingenious and 

 well worthy of imitation. 



The method of working is long work and pillar and stall. 

 Long work is common in North Wales, and is adopted in a 

 few instances in Lancashire and Cheshire. The pillar and 

 stall w^ork of North Wales is known as "wicket work." The 

 wickets or stalls vary in width up to 24 yards, and the pillars 

 to 15 yards. The pillar and stall has various modifications. 

 The common system is termed "straight ends and walls." 

 The straight ends are drifts from 4^ feet to 6 feet wide, and 

 the walls or pillars about 10 yards wide, varying according to 

 circumstances. The process, when the system is properly 

 carried out, is to drive first a pair of levels to the boundary, 

 and there commence the straight ends for the pillar work; 

 commencing to work the pillars at the boundary and working 

 backwards towards the shaft, leaving the goaf behind. In 

 this way each foot of the seam yields fully one thousand tons 

 of large and mixed coals per statute acre. The system of 

 working, in this way, from the extremities prevents waste by 

 crushes or squeezes, and also simplifies the ventilation. Com- 

 pleting the levels before the end and pillar work is com- 

 menced has the effect of draining the seam of the greater part 

 of its firedamp, when the workings are in the simplest form, 

 and when almost any quantity of air can be directed to the 

 most fiery points. Indeed, some of the very fiery seams are 

 almost unworkable with safety by pillar and stall work, unless 

 thus first drained of their firedamp. The ends alluded to are 

 sometimes driven from 3 to 8 yards wide ; and occasionally 



