all opening at the top, and that the mass was of
such a character that it could easily be removed with pick and
shovel, but he had nothing. With desperate energy, he began
tearing away the earth and rocks with his hands, then to his intense
relief, after a few moments' work, he heard voices on the other
side. Houston listened; it was Jack and Mike, who, having waited for
him in the tunnel, expecting him to join them immediately, had
become alarmed at his non-appearance, and were returning with
their picks and shovels, which they had taken out with them, calling
him and searching for him.

Houston shouted, and they hastened to the rescue, and the entrance was
very quickly cleared sufficiently for Houston to crawl through. Before
passing through, himself, however, he lifted Bull-dog, and carefully
handed the unconscious form to Jack.

"Who is this?" the latter asked in surprise.

"Bull-dog, the little hero who has saved our lives by sacrificing his
own," Houston replied.

"Is he still living?"

"Yes, but unconscious."

Silently and tenderly Jack handed the little fellow to the tender-hearted
Mike, who at once started toward the tunnel with his burden, while
Jack turned to assist Houston.

At that instant, there came the third explosion, which was farther
underground than either of those preceding. It was but a short
distance from them, and an immense scale of overhanging rock quivered
for an instant, then fell, throwing its fragments in every direction.
Mike, at the distance which he had already gained, escaped unhurt.
Jack and Houston sprang in opposite directions, but the pieces of
flying rock overtook them, though they escaped being buried beneath
the mass as it fell. They were both thrown to the ground; Houston
staggered to his feet, badly bruised and cut and his left arm broken,
but Jack remained motionless.

Hearing Houston's call, Mike quickly returned, and he and Houston
found that Jack was still alive, though badly injured about the head.
The full extent of his injuries they realized they would be unable to
ascertain until they could reach the surface. Together they consulted
as to the best course to pursue. Mike wished to go back and get help
immediately, but Houston insisted that they must first remove Jack and
little Bull-dog as speedily as possible, as there was danger of other
explosions following now in rapid succession, and also danger from the
smoke and gases of the gradually approaching flames