president's address. 339 



In different parts of the Coalfield various qualities of coal 

 are found, the two main divisions being the Anthracite and the 

 Bituminous Coal. Between these too extremes there are various 

 minor differences, such as the " semi-bituminous," the " free- 

 burning," and the far-famed " smokeless steam " coal. I will 

 not weary you with a description of the geological position of 

 these various sorts, but merely state that it has been estimated 

 that there are 410 square miles of Bituminous Coal, the same 

 area of Anthracite, and about 180 square miJes of what may be 

 called transition coal, lying, as before said, between those two 

 great divisions. 



Various theories have been given to account for this 

 extraordinary variation in the coal of the same basin, some 

 having suggested electricity, others the immense pressure which 

 the strata has been subjected to by nature's upheavings. Very 

 many varieties of fossil plants, ferns, reeds, &c., are found, 

 together with shells in the Third Series, in which the ferns so 

 abundant elsewhere are very scarce. 



Some of the shafts sunk to work the coal seams are of 

 considerable depth, the deepest at present being, I believe, over 

 370 fathoms, at Harris's Navigation Colliery. The mode of 

 working the coal varies as a general rule to suit the inclination 

 or "steepness" of the veins; where the veins or seams are 

 pretty flat or level the system called the " longwall " prevails, 

 whereas in the steep measures the pillar and stall mode of 

 "getting" is found the most suitable. I will not trouble you 

 with a description of these modes of working, which I think 

 would be too much of technical detail for an address of this 

 character. 



In consequence of the highly inflammable and explosive 

 nature of the gas given off by most of the seams of coal, it is 

 absolutely necessary for the safety of the men, to have attached 

 to every colliery some extensive means for artificial ventilation. 

 In old days this used to be attained by a furnace at the up-cast 

 shaft, by which means the air being rarified at the furnace, 

 caused a tendency to a vacuum, and drew down the down-cast 

 shaft fresh air for ventilating the workings, and making the gas 

 escaping uninflammable. Generally speaking now this furnace 



