932 GEOLOGY OF OHIO. 
PLEURE ASK 
STRUCTURE OF COAL AT MINE N@i3 OHIO 
CENTRAL COAL COMPANY, CORNING, 
Coat —cejectea. 
Slovo 
Coole 
Hovu Coal, cejected,__| 
Croker oft Va. wivmetn 
Sost Coal, ;reje ced. —_____ 
Bone Cool rejected ees 
Se Slate. 
& a ae oe 25 a 
The seam is divided in mining precisely as indicated in the right- 
hand side of Fig XCa, except that recently the “horn coal” has been 
reduced several inches by splitting off the bottom portion and sending 
it out as ‘‘splint coal,” which now finds sale and acceptance in all 
markets. Between 5 and 6 feet of coal are now brought out. 
‘The rooms of all the mines are worked 25 feet wide. Pillars and 
ribs are left 10 feet in width, and their strength thus far seems adequate 
to all demands. The coal is in all cases worked to the third main slate, 
which forms a roof of great strength and excellence. This slate is 
black, and contains an infinite number of sigillaria impressions. The 
coal below this slate measures 8 to 8% feet in thickness. Posts are cut 
83 feet in length, and are set in the middle of the room, and the roads 
consequently lie along side of the ribs. This arrangement facilitates 
the drawing of the ribs, as all the refuse coal, the volume of which is 
very large, is stored in the middle of the room. Ribs are drawn early, 
so as to relieve the weight upon the entries. Whenever they are drawn, 
the rider seam is brought down to some extent. 
Entries are driven in line with the cardinal points. This throws 
them a trifle off from the face and ends of the coal, but in working the 
coal, the miner secures the full advantage of the face by keeping one 
side of the room a little in advance of the other. 
