was in the drilling gang, Tom?"

"Juss so! Working under the wall bed of the canyon."

"That lets some light on to the subject. You can dismiss the others.
Come with me, Tom."

Twenty minutes later Geoffrey stood among the boulders that the
shrunken river had left exposed near the foot of a giant cliff which,
instead of overhanging, thrust forward a slanting spur into the rush of
water, and so formed a bend. It was one of the main obstacles
Geoffrey, who wondered at the formation, had determined to remove by
the simultaneous shock of several heavy blasting charges. To that end
a gang of men had long been drilling deep holes into the projecting
spur, and on the preceding day charges of high explosives had been sunk
in most of them with detonators and fuses ready coupled for connection
to the igniting gear. Geoffrey stood upon a boulder and looked up at
the tremendous face of rock which, rising above the spur, held up the
hill slope above. The stratification was looser than usual, and
several mighty masses had fallen from it into the river. There were
also crannies at its feet.

"You've seen all the drilled holes. Anything strike you yet?" inquired
Mattawa Tom.

"Yes," was the answer. "It occurs to me that French Louis said he
couldn't tally out all the sticks of giant powder that he'd stowed away
a week or two ago. I think you foolishly told him he couldn't count
straight."

"I did," admitted Tom from Mattawa. "Louis ain't great at counting,
and he allowed he'd never let go of the key to the powder magazine."

"I fancy a smart mechanic could make a key that would do as well,"
remarked Geoffrey. "It strikes me, also, after considering the strata
yonder, that, if sufficient shots were fired in those crannies, they
would bring the whole cliff and the hillside above it down on top of
us--you'll remember I cautioned you to drill well clear of the rock
face itself? Now, if coupled fuses were led from the shot holes we
filled to those we didn't, so that both would fire simultaneously,
nobody afterwards would find anything suspicious under several thousand
tons of debris. I'm inclined to think there are such fuses. Take your
shovel, and we'll look for them."

They worked hard for half an hour, and then Geoffrey chuckled. Lifting
what looked like a stout black cord from among the rubble where it was
carefully hidden, Mattawa Tom said: "This time I guess you've struck it
dead."

"Follow the thing up," G