Duncan had almost forced the miner into a chair.

"Tell me," he said, "how is it that you----"

"That I'm a miner? You think of me as an educated engineer, eh? Well,
that's a long story and not at all so sad a one as you might suppose.
I'll tell you all about it at another time. But it can wait, while there
are some other things that should be said now--things that vitally
affect the affairs you have in charge."

"It is very good of you to come to me with suggestions, and they will be
very welcome, I assure you, and very helpful, I've no doubt. For I have
faith in your skill as an engineer."

"My skill still remains to be proved," answered the other with the
merest touch of sadness in his utterance. "But, at any rate, I've had
the very best engineering education that the schools can give. Never
mind that--and never mind me. I didn't come here to talk of myself. I
want to talk to you about this mine."

"Good. That is what I am here for. Go on."

"Well, everything here is wrong. With your readiness of perception you
must have seen that for yourself. With the general management I have
nothing to do. I'm only one of the miners. But there is a problem of
ventilation here that ought to be solved, and I have come simply to
offer a solution, in the interest of the company that pays my wages and
still more in the interest of the miners. Two of them were killed by
choke-damp a little while ago, four of them are now ill from the same
cause, while all of them are earning less than they should because the
best and most easily accessible headings are closed."

"Is there any very serious difficulty involved in the problem of
ventilating the mine?"

"None whatever--at least no engineering difficulty."

"Just what do you mean?"

"I prefer not to say."

"Perhaps I can guess," said Duncan. "I have myself discovered a very
serious difficulty in the personal equation of Mr. Davidson. He does
not want to ventilate the mine--he has his own reasons, of course. That
difficulty shall no longer stand in the way. I shall eliminate it at
once. Go on, please, and tell me of the engineering problem."

"It scarcely amounts to a problem. The mine lies only about seventy-five
feet below the surface. At its extreme extension the depth is
considerably less, because of a surface depression there. What I suggest
is this: Dig a shaft at the extreme end, thus making a second opening,
and pass air freely through the mine from the one opening to