here. My word is law, to Mr. Davidson as completely and as
absolutely as to the old fellow who scrubs out this office--or doesn't
scrub it, for it's inexcusably dirty. Davidson can no more discharge you
than he can discharge me. I don't know yet what I shall do with
Davidson. But at any rate he has no longer the power to discharge you,
so you need have no fear in that direction. Go on, now, and tell me how
you purpose to ventilate the mine. I'm mightily interested."

"Thank you," said Temple. "My plan is perfectly simple. You can't force
air down into a mine with any pump that was ever invented, or any pump
that ever will be devised by human ingenuity. But you can easily and
certainly draw air out of a mine. And when there are two openings to the
mine--one at either end--if you draw air out at one end fresh air will
of itself rush in at the other end to take its place. My plan is to sink
a shaft at the farther end of the mine, and to build an air-tight box at
the surface opening, completely closing it, except for an outflow pipe.
Then I shall put one of the big ironclad fans into that box _upside
down_. When it is set spinning it will suck air out of the mine, and
fresh air will rush in at the main shaft to take the place of the air
removed."

Duncan was intensely interested. Very eagerly he bent forward as he
asked:

"You are confident of success in this?"

"More than confident. I'm sure."

"Quite sure?"

"More than quite sure; I'm absolutely certain. I've tried it."

"Tried it? How?"

"I've reconstructed the mine in miniature. I've made a little fan whose
suction capacity is in exact proportion to that of the big fan which I
propose to use in the mine. I have fully experimented, and I tell you
now, Guilford Duncan, that if you permit me to carry out the plan, I'll
create a breeze in that mine which will compel you to hold on to your
hat whenever you go into the galleries."

Duncan rarely showed excitement. When he did so, it was in ways peculiar
to himself. At this point he rose to his feet, and with an unusually
slow and careful enunciation, said:

"Go to work at this job early to-morrow morning, Dick--or this morning,
rather, for it is now one o'clock. Your wife is Mary, of course?"

There was a choking sound in Duncan's voice as he uttered the words.

"Yes, of course," answered the other, instinctively grasping Duncan's
hand and pressing it in warm sympathy.

"Will you bear her a message from me?"