Question

Where coal is getting exhausted?

Answer 1

Because of the  gritty facts at the bottom of the predictions of evil, and among such facts, showing that all is not well with us, are these :—Taking into account the difficulty of working steadily in an at- mosphere much above blood-heat, and setting off the fact that the deepest mines are generally the driest, and, owing to that circumstance, the most suitable for working, and the probability of our being enriched with inventions and expedients for cooling the air of mines by such means as "the long-wall" system, the possibility of carrying work- ings to a depth of four thousand feet may be assumed.