was afoot and alert when he said: "You know the
probabilities better than any of us: how much time have we before these
flood tides will come down?"

She had risen to stand with him, steadying herself by the hook of the
derrick-fall. "I don't know," she began; and at that instant a great
slice of the zirconium mine dump slid off and settled into the eddying
depths with a splash.

"It is nothing but a few more cubic yards of the waste," he said, when
she started and caught her breath with a little gasp.

"Not that--but the door!" she faltered, pointing across the chasm. "It
was shut when we came out here--I am positive!"

The heavy, iron-studded door in the bulkhead was open now, at all
events, as they could both plainly see; and presently she went on in a
frightened whisper: "Look! there is something moving--this side of the
door--among the loose timbers!"

The moving object defined itself clearly in the next half-minute; for
the two at the derrick-heel, and for another--young Blacklock, who was
crouching behind his rejected thorough-stone directly opposite the mine
entrance. It took shape as the figure of a man, slouch-hatted and
muffled in a long coat, creeping on hands and knees toward the farther
dam-head; creeping by inches and dragging what appeared to be a six-foot
length of iron pipe. The king's daughter spoke again, and this time her
whisper was full of sharp agony.

"_Breckenridge!_ it is my father--just as I have seen him before! That
thing he is dragging after him: isn't it a--merciful Heaven! he is going
to blow up the dam! Oh, for pity's sake can't you think of some way to
stop him?"

There are crises when the mind, acting like a piece of automatic
machinery, flies from suggestion to conclusion with such facile rapidity
that all the intermediate steps are slurred and effaced. Ballard marked
the inching advance, realised its object and saw that he would not have
time to intervene by crossing the dam, all in the same instant. Another
click of the mental mechanism and the alternative suggested itself, was
grasped, weighed, accepted and transmuted into action.

It was a gymnast's trick, neatly done. The looped-up derrick-fall was a
double wire cable, running through a heavy iron sheave which carried the
hook and grappling chains. Released from its rope lashings at the
mast-heel, it would swing out and across the canyon like a monster
pendulum. Ballard forgot his bandaged arm when he laid hold of the