The miner had hardly ceased speaking when a huge volume of gas burst through the aperture, nearly suffocating the party and extinguishing the lamps instantly.
"Jump to it lively, boys!" Joe cried hoarsely, as he began shoveling back the earth. "When you can't work any longer get a breath of fresh air in the drift."
There was every danger that the lower level might be so filled with the noxious vapor as to cause an explosion, and both men and boys labored manfully.
All were working blindly, but the general direction of the aperture was known, and the greater portion of the earth could be thrown with a fair degree of accuracy.
Ten minutes passed and the flow of foul air was partially checked. Twice had each person been forced to retreat to the main drift, and Fred was about to go for the third time when it seemed as if the flooring of dirt gave way beneath his feet.
Half suffocated by the gas, and overwhelmed by the falling fragments, he hardly realized what had occurred until finding himself in what was unmistakably another and yet lower tunnel or drift.
CHAPTER XV
A DISCOVERY
After the first alarm passed away, Fred understood that he had fallen but a few yards, and the earth which covered him represented only a very small portion of the upper tunnel's floor.