ster click. Alert in every fiber, his
gaze swept the bluff--and stopped when it met a pair of beady eyes
peering at him over the edge of the precipice.

The two pair of eyes fastened for what seemed like an eternity, but
could have been no longer than four ticks of a clock. Neither of the men
spoke. The outlaw fired first--wildly, for the arm which held the rifle
was cramped for space. Keller's revolver flashed an answer which tore
through Irwin's teeth and went out beneath his ear. With a furious oath
the man dropped his weapon and flung himself upward and forward, landing
in a heap almost at the feet of the detective.

"Don't move!" ordered the latter.

Brad writhed forward awkwardly, knew the shock of another heavy bullet
in his shoulder, and catching his foe by the legs dragged him from his
feet. Keller's revolver was jerked over the edge of the precipice as he
let go of it to close with the burly ruffian.

Both of them were unarmed save for the weapons nature had given them.
The detailed purpose of the struggle defined itself at once. Irwin meant
by main strength to fling the detective into the gulf that descended
sheer for five hundred feet. The other fought desperately to save
himself by dragging his infuriated antagonist back from the edge.

They grappled in silence, save for the heavy panting that evidenced the
tension of their efforts. Each tried to bear the other to the ground, to
establish a grip against which his foe would be helpless. Now they were
on their knees, now on their sides. Over and over they rolled, first one
and then the other on top, shifting so fast that neither could clinch
any temporary advantage.

[Illustration: THEY GRAPPLED IN SILENCE SAVE FOR THE HEAVY PANTING THAT
EVIDENCED THE TENSION OF THEIR EFFORTS. _Page 340_]

Yet Keller, with a flying glance at the cliff, knew that he was being
forced nearer the gulf by sheer strength of muscle. Irwin, his jaw
shattered and his shoulder torn, was not fighting to win, but to
kill. He cared not whether he himself also went to death. He was
obsessed by the old primeval lust to crush the life out of this lusty
antagonist, and his whole gigantic force was concentrated to that end.
He scarce knew that he was wounded, and he cared not at all. Backward
and forward though the battle went, on the whole it moved jerkily toward
the chasm.

The end came with a suddenness of which Larrabie had but an instant's
warning in the swift flare of joy that l