Mr. Buddle on Mining Records. 



315 



of clear merchantable coal, through the whole extent of the colliery, may be 

 safely stated at 6 ft. 6 in. on the average, exclusive of the Ground Coal, 

 as shewn in the accompanying Section. 



HIGH MAIJNT 



Good. CoaZ....Jk 



Swa<Z-- 

 Coarse CoaZ-" 



Very- Coarse. 

 Slaty CoclL "" 



In some parts, the roof of the seam was Post or Sand Stone, but the 

 greatest proportion of it was a fine tough blue or dark grey Metal Stone. 

 The bottom of the seam was separated from the Ground Coal by a 

 strong dark-coloured Slaty Thill called Swad (an inferior sort of fire clay), 

 which when dry, as it generally was, made an excellent road for the 

 broad-wheeled rollies, which carried a 24 peck corf, and were drawn 

 from the face of the workings to the railways leading to the pits by horses. 

 This Swad seldom exceeded 2 inches in thickness. The roof was so good 

 as seldom to require more than two rows of props in a 4 or 5 yard board, 

 one of which was required for the support of the air brattice. For several 

 years after the working of the High Main Seam commenced, it was subject 

 to blowers of inflammable air from the roof, especially from the threads or 

 fissures in the Post Roof ;* but latterly, especially after an extensive work- 



* Sand Stone. 



