said Miss
Nellie, when they were once more seated in the car, and Harry, was
taking them towards a distant heading.

"Yes, indeed, he is," answered Derrick, proud to hear his mule thus
praised; "and I love him as much as--as he loves me," he finished, with
a laugh.

They spent several hours in visiting different parts of the mine, and
becoming acquainted with all the details of its many operations. At the
end of one heading they found the miners who had just finished drilling
a hole deep in the wall of coal beyond them, and were about to fire a
blast. The visitors were intensely interested in watching their
operations. First a cartridge of stiff brown paper and powder was made.
The paper was rolled into the shape of a long cylinder, about as big
round as a broom-handle, the end of a fuse was inserted in the powder
with which it was filled, and the cartridge was thrust into the hole
just prepared for it. Then it was tamped with clay, the fuse was
lighted, the miners uttered loud cries of "Blast ho!" and everybody ran
away to a safe distance.

In less than a minute came a dull roar that echoed and re-echoed through
the long galleries. It was followed by a great upheaval of coal, a dense
cloud of smoke, and the blast was safely over.

These miners had a loaded car ready to be hauled away. One of them asked
Derrick if he would mind hitching it on behind his empty car, and
drawing it to the junction, adding that the boy who had taken his place
that day was too slow to live.

"All right," said Derrick. "I guess we can take it for you."

So, with two cars instead of one to pull, Harry Mule was started towards
the junction. On the way they had to pass through a door in charge of a
boy who had only come into the mine that day. This door opened towards
them, and they approached it on a slightly descending grade.

As they drew near to it, with Harry Mule trotting briskly along, Derrick
shouted, "Door!"

Again he shouted, louder than before, "Door! door! Holloa there! what's
the matter?"

The little door-tender, unaccustomed to the utter silence and solitude
of the situation, sat fast asleep in his chair. At last Derrick's
frantic shoutings roused him, and he sprang to his feet, but too late. A
crash, a wild cry, and poor Harry Mule lay on the floor of the gangway,
crushed between the heavy cars and the solid, immovable door!

CHAPTER XIV

A LIFE IS SAVED AND DERRICK IS PROMOTED

Mrs. Halford and her daught