Accordingly, he had retreated and hastened back through the passageway into the Automaton’s den.

“Quick!” he shouted to the horde of emissaries in the place.  “Bring dynamite, electric wires, and a rack-bar.  They think they have us trapped.  But if they try to follow me here, I tell you it will mean certain death to them.”

The emissaires hastened to obey him.  They brought the explosive and the means to detonate it, and carried the stuff into the passageway, where they made the connections.  An emissary stepped forward and volunteered to use the rack-bar when the time came, but Balcom waved him away.

“No,” he growled.  “No one can take my revenge from me.  I’ll do the killing.”

The emissaries fell back and went into the den.

Balcom was making some final adjustments when the great rock separating the passageway from the Graveyard of Genius swung slowly on its balanced hinges.

Startled from his work, even though he had expected the thing, Balcom looked up, and in the passageway caught a glimpse of the dim outline of his arch-enemy, Locke.

Balcom had been right.  Locke had found the clue to the secret entrance to the tunnel.

He worked feverishly to complete the final connection, but almost before he finished Locke charged and the battle was on.

Up and down the passageway they fought.  Although Locke was the younger man, yet in Balcom he found a giant of strength.

It was a fight between these two alone, for no emissary, no Automaton, now entered that passage of death.

Neither uttered a sound.  Neither had a weapon.  It was the primitive struggle of man to man for life.

But now Locke’s youth and clean living began to tell in his favor and he sensed that his adversary was weakening.  He redoubled his efforts.

After a particularly vicious blow from Locke, Balcom threw up his hands and toppled over backward—­in the direction of the rack-bar itself.

Locke tried to throw Balcom’s body out of the way.  It was too late.  With a thud Balcom crashed full upon the plunger, driving it home.

There was a blinding flash, a dull roar, and the earth rocked.  Huge boulders were tossed about like feathers and the roof of the passage caved in.

Balcom was killed instantly.  Locke, with better fortune, had been hurled to the ground, where the earth and rocks, in falling, had formed a sort of arch over his body.

He was alive, though barely conscious.  He knew that soon a search would be made for him.  But, buried under tons of earth and rock, could any rescuers reach him in time?  Was this the end?

CHAPTER XXIV

For a long time Locke lay quite still.  The shock to his nervous system had been terrific, and, although physically almost uninjured, he had lost his usual grip on himself and felt very helpless.