nded Peggy. "Paul Blackton, you're----"

The engineer's laughter was like a giant's roar in the cavern, and Joanne
gave a gasp, while Peggy shiveringly caught Aldous by the arm.

"There--I've got the lantern!" exclaimed Blackton. "There isn't any danger,
not a bit. Wait a minute and I'll tell you all about it." He lighted the
lantern, and in the glow of it Joanne's and Peggy's faces were white and
startled. "Why, bless my soul, I didn't mean to frighten you!" he cried. "I
was just telling you facts. See, we're standing on a solid floor--four feet
of packed rock and cement. The dynamite and black powder are under that.
We're in a chamber--a cave--an artificial cavern. It's forty feet deep,
twenty wide, and about seven high."

He held the lantern even with his shoulders and walked deeper into the
cavern as he spoke. The others followed. They passed a keg on which was a
half-burned candle. Close to the keg was an empty box. Beyond these things
the cavern was empty.

"I thought it was full of powder and dynamite," apologized Peggy.

"You see, it's like this," Blackton began. "We put the powder and dynamite
down there, and pack it over solid with rock and cement. If we didn't leave
this big air-chamber above it there would be only one explosion, and
probably two thirds of the explosive would not fire, and would be lost.
This chamber corrects that. You heard a dozen explosions last night, and
you'll hear a dozen this afternoon, and the biggest explosion of all is
usually the fourth or fifth. A 'coyote' isn't like an ordinary blast or
shot. It's a mighty expensive thing, and you see it means a lot of work.
Now, if some one were to touch off those explosives at this minute----
What's the matter, Peggy? Are you cold? You're shivering!"

"Ye-e-e-e-s!" chattered Peggy.

Aldous felt Joanne tugging at his hand.

"Let's take Mrs. Blackton out," she whispered. "I'm--I'm--afraid she'll
take cold!"

In spite of himself Aldous could not restrain his laughter until they had
got through the tunnel. Out in the sunlight he looked at Joanne, still
holding her hand. She withdrew it, looking at him accusingly.

"Lord bless me!" exclaimed Blackton, who seemed to understand at last.
"There's no danger--not a bit!"

"But I'd rather look at it from outside, Paul, dear," said Mrs. Blackton.

"But--Peggy--if it went off now you'd be in just as bad shape out here!"

"I don't think we'd be quite so messy, really I don't, dear," she
persis