Ashman was beginning to ask himself how he was to continue the advance in the darkness, which must become impenetrable as they passed beyond the limit of the moonlight, when he perceived the water into which he dipped the paddle.

Not only that, but it grew more distinct as he progressed, until once more the form of his beloved came out to view, as she sat near him in the canoe.

Wondering what it all meant, he gazed ahead.  The surface of the water grew plainer, as his eye ranged along the tunnel, until, only a short distance away, the view was clearer than on the lake itself, beneath the full moon.

What was the explanation of this wonderful sea of illumination into which he was guiding the canoe?

CHAPTER XXX.

A GUESS.

Standing in the door of the building, his figure so wrapped in gloom that it was invisible to the fierce Murhapas, Professor Grimcke cautiously peered out upon the multitude that were clamorously seeking the death of himself and comrade.

The horde seemed to be everywhere.  They were glaring over the river bank, behind which they could find secure shelter by merely dropping their heads; they were crouching at the corners of the adjacent houses, the king’s residence affording screen to fully a score.  Not yet fully recovered from their panic, they appeared to be awaiting the leadership of some strong man who held the fire-arms of the explorers in less dread than they.

A form rose upright along the Xingu, at the upper portion of the line of savages.  In the full moonlight he was as clearly revealed as if at mid-day.

It was with strange feelings that Professor Grimcke saw that this individual belonged to the same race as himself.  He was one of the two white men that had lived for years among the Murhapas and who had instigated the furious assault upon them.

“You have earned your fate,” muttered the German, bringing his unerring Winchester once more to his shoulder, and sighting as best he could at the unconscious miscreant, who appeared to be conversing with some one sitting on the ground at his side.

The finger of Grimcke was pressing the trigger when, yielding to an unaccountable impulse, he lowered the weapon.  He was impatient with himself that his heart should fail him at the critical moment, but perhaps it was well it was so.

“You and I ought to be friends,” he reflected, “and it is not my fault that we are not, however, I cannot shoot you down like a dog, though you deserve it.”

The emotion which checked him so unexpectedly, also prevented his renewing fire upon the Murhapas, who were really less guilty than he.

He had decided to await the next demonstration before discharging his gun again.

Jared Long was as vigilant and alert as his friend.  It may be doubted whether he would have spared Waggaman, had he been given the opportunity to draw bead on him.  He realized too vividly that the two defenders never would have been in this fearful situation but for the machinations of those two men.