"It doesn't look like anything!" replied Sandy. "It's composed of
natural gas, and they call it a blower because it blows up out of
crevices in the coal and in the rocks."

"If I should light a match, would it set it on, fire?" asked Tommy.

"I wouldn't like to have you try it!"

The boys continued on their way for some moments, and then Tommy
stopped and extinguished his light, whispering to Sandy to do the
same.

"What's that for?" demanded the latter.

"Didn't you hear that noise behind the cribbing?" asked Tommy.

"Rats, probably!"

"Rats nothing!" replied Tommy. "Rats don't make sounds like people
whispering, do they? Keep still a minute, and we'll find out what it
is!"

"You'll be, seeing a light next!" Sandy suggested.

"I see it now!" answered Tommy.

Sandy saw it, too, in a moment. It seemed at first to be floating in
the air at the very top of the gangway. It moved from side to side,
and finally dropped down nearer to the floor. There seemed to be no
one near it or under it. Its small circle of illumination showed only