y,
without a second's pause, each man streaming with perspiration as he
toiled. Rails were put down as fast as the obstruction was dug away.
The timber gangs strove like madmen. Each shift was for two hours
only, with no pause between, for there were men and to spare.

So the day and the night passed.

At ten o'clock on Sunday morning, there came a cry--

"She's fallin' again!"

A tremor ran through the mine.

Another shifting of the strata imperilled all the excavation that had
been done.

A few minutes' hesitation might have been fatal, but the timber gangs
rushed forward, though the props were bending on every side of them
and threatened, from second to second, to engulf them in falling rock.
In a haste that approached to panic, timbers were thrust up and
braced, so that but a small section of the roof fell.

Some of the miners quit, the more readily as a couple of them were
badly hurt in the little fall, but for every man who showed the white
feather, there were a score to volunteer. They were led by Owens
himself, who was at the bottom of the shaft when the fall came. With
all the fire of his adventurous youth, he seized a pick and ran
forward to the most dangerous place, crying:

"Those men are to be got out, or I'll die down here with them! Who
follows?"

There was no farther talk of quitting.

On Monday there arrived from Washington a Bureau of Mines expert, with
a new listening-device, known as a geophone. This is an instrument
worked on the microphone plan, so sensitive that it responds to the
slightest vibration, even through dense rock-strata, hundreds of feet
thick.

"Stop work, all!" came the order. "Not a word, not a whisper! Keep
your feet and hands as still as if you were frozen!"

There was a tense five minutes as the geophone expert listened.

Presently he detached from his head the ear-clamps leading to the
microphone receiver.

"The men are alive!" he declared. "I hear them knocking!"

"To work, men!" cried the boss, and the picks rang with redoubled
zest.

It was Tuesday, shortly before dawn, when the rescuers pierced the
first obstruction, only to find another and a worse break beyond.

A draft of air sucked through. Almost immediately the caps of the
safety lamps showed blue. At the same time, the safety inspector
called, "Back from the face, men! Back, all!"

He pointed to the little cage he had been holding.

The canaries had collapsed!

Carbon monoxide was pouring o