The young man gave his promise, and, bidding them good-by, he began stealing down the stream, keeping as closely within the wall of shadow as he could, and advancing with as much care as though he saw the fierce savages across the Xingu watching for just such a movement.
The peculiar nature of the ground rendered progress easy, and he paused after going about a furlong, believing he had advanced sufficiently far to accomplish what he wished.
The essential work of Ashman was to cover one-half the distance between him and the camp, the further half being under the surveillance of the guards on duty there.

Since he could also overlook the stream equally far in the opposite direction, it will be seen that the savages would have to make their crossing nearly a fourth of a mile below the camp to escape observation.
All this was on the theory that the lone sentinel was really able to scan the space with sufficient clearness to detect anything of the nature apprehended, and that the savages themselves had no suspicion of any such extra care on the part of their enemies.
The astonishing brilliancy of the moonlight will be appreciated, when it is stated that Ashman felt not the least doubt of his ability to meet every requirement of his self-assumed duty.
Well aware, from previous experience, of the insidious approach of slumber to the most vigilant sentinel, when unable to keep in motion, he avoided sitting down, even though he never felt more wakeful.

So long as he stood erect, there was no danger of his lapsing into unconsciousness.
Another indispensable requirement was that he should not be tempted into venturing from the shadow where he stood, for such an act was liable to bring about discovery and defeat the very object that had brought him thither.
The moon was so nearly in the zenith that the shade from the edge of the forest did not project halfway across the open space to which we have alluded.

It was in this partial gloom that the young man took his station, placing himself as far back as he could without standing among the trees themselves.
He was in the position of one who feels that the lives of his dearest friends are placed in his hands.

To him, nothing was more evident than that the revengeful savages would attempt to cross the stream and make another stealthy attack upon the camp.