THE RHONDDA COLLIERY. 



265 



ever, is so slight that when a skip is proceeding towards the 

 tippler the wheels force it to return to its proper position. 

 Should a skip break away near the weighing machine and pass 

 down hill, it would run oft' the rails at the point where the 

 continuity of the line is broken. 



The bords are made 8yds. wide, with 10yd. pillars, and are 

 50yds. long between cut throughs. A cut is then taken off for 

 2yds. deep on either side of the bords with the Sullivan ma- 

 chine, thus making the bord 12yds. wide, and the intervening 

 pillars 6yds. There is very little water in the mine, and this 

 is at present handled by a Knowles steam pump ; but later on 

 a pump shaft will be sunk in the deepest known part of the 

 seam, and the pump will be removed. 



Fig. 170. Skips proceeding to the Screens, Rhoiidda. 



Ventilation is carried out by means of a furnace, which is 

 cleaned out and banked up for the night. All the coal is 

 removed right up to the roof of the furnace chamber, and air 

 circulates on either side of the furnace, so that there is no 

 fear of the coal in the seam catching alight. Although this 

 is not a gassy mine, and naked lights are used, yet a man 

 tests every working face with a safety lamp before the miners 

 go to work, and makes marks to that effect to prove he has 

 been there. 



Steam is generated in three Cornish boilers and one Stirling 

 boiler. The standard Stirling boiler consists of three upper or 

 si earn drums, and one lower or mud drum, which are connected 

 together by three banks of tubes, and short circulating tubes 



