COAL MINING. 353 
worked on a plan nowhere else followed in Ohio, owing to the greater 
depth of the incumbent strata, as well as to the presence of firedamp ,which 
is given off in dangerous quantities. The plan is a model after that in 
use in the North of England, in which district the art of mining is bet- 
ter understood than in any other coal field in the,world. 
The rooms in the Steubenville shaft mines are made 18 feet wide, 
the cross-cuts or walls 12 feet wide, the pillars left being 24 feet in thick- 
ness, and 72 feet in length. The walls head off the rooms at right an- 
gles, and are driven straight forward in the butts of the coal, the rooms 
being driven on the face. The main entries, which follow the face of 
coal in lines parallel with the rooms are 10 feet wide and are double. 
The presence of fire-damp in the mine makes ventilation a paramount 
necessity, and so well is this art understood by the superintendents that 
not a single accident by explosion has occurred in the past 17 years. All 
of the mines rely on the furnace for the necessary currents of air, and 
every advantage is taken of the natural law to get the best results. The 
furnaces are made 53 feet wide, 35 feet high above the bars, and are 30 
to 40 feet in length. The upcast of the shaft is roomy and dry, the air 
courses of the mine are wide and as straight as circumstances will per- 
mit, and fully three times as much air is set in motion with the 
same expense of attendence and fuel as in many other mines. The 
greater depth of shaft at Steubenville assists in creating the flow of air, 
for the practical power of the furnace is in proportion to the length of 
the up-cast, the power being as the ratio of the depth. The air current 
is kept well up toward the face of the workings; no sooner is a new 
holing made from the wall into the room face, than the outer wall is 
bratticed up and made air-tight. Should the current of air playing along 
the air courses be too strong for the comfort of the miners, an opening 
is left in the outer break-through for the escape of air until the miner 
has pushed his room ahead in the “fast” beyond the sweep of the circu- 
lating stream. 
In order to guard against the possibility of danger none of the work- 
men in this district are allowed to descend any of the shafts in the mor- 
ning, under any circumstances, until the mine has been thoroughly 
examined withasafety-lamp. At 4 o0’clock in the morning, the mine boss, 
assisted by several trusted deputies, descend the mine, safety-lamp in 
hand. Every gallery and room is examined, each fire viewer traversing 
22 G. 
