the leader of the Wolf patrol to solve the puzzle.

Without saying a word, Hugh jumped to his feet and went outside to
take a look around. He came back almost immediately, and his face
told them that his investigation instead of clearing up the mystery
had only added to it.

"What did you find out, Hugh?" questioned Bud.

"Not a single cloud to be seen in all the sky!" said the other
impressively.

"Whew! that seems queer, doesn't it?" faltered Bud.

"And it must be almost down to freezing, into the bargain," added
the patrol leader. "I've seen lightning before, in February even,
but always during a thaw. Fact is, boys, I can't believe that it was
either lightning or thunder we saw and heard."

"But, Hugh, what could it have been then?" demanded Ralph.

"If we were nearer the granite quarries, I'd say they had set off an
extra big blast. You know we sometimes hear a faraway boom over home.
Sound travels many miles when there's a sub-strata of rock like a
ledge to act as a conductor."

"Yes, but then I understood work had stopped there for the season
the Saturday before Thanksgiving," volunteered Bud. "Still, they
may be doing some blasting, just to keep things moving as long
as the snow holds off. If that was a blast of dynamite, it must
have been a stunner to make the earth quiver so much."

Hugh made no reply. Plainly he was deeply impressed with the
mysterious nature of the unannounced explosion. And when once Hugh
started to find out what things meant, he seldom let the matter
drop until he had accomplished his purpose.

Bud also went to the door and looked out, his curiosity having been
duly aroused. Hence he did not hear Ralph make a significant
admission.

"Now that I come to think of it," the other remarked, "for the last
two nights I can remember hearing a distant, dull sound that I
thought was a heavy blast off in this quarter. I chanced to be
outdoors each night about ten o'clock. It's come much earlier
this time, it seems; but, anyhow, that is getting to be a regular
nightly performance I wonder if they are working over in the granite
quarries? I'm something of a sticker when anything bothers me like
this, and for three cents I'd take a turn over that way to-morrow
just to satisfy my mind."

"I was wondering whether those two men you saw could have had
anything to do with that queer crash and flash?" suggested Hugh
slowly.

"Ginger! I wonder now!" exclaimed Ralph, who apparentl