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.  They surely must feel enough dread of the terrible weapons that had wrought such havoc, not to defy them again, but would make their next demonstration in the nature of a flank movement.

One fact caused Ashman some surprise; he had seen nothing of any canoes or boats, which were plentiful along the shores of the Xingu below.  It was not to be supposed that such a powerful and brave tribe as those on the other side, would live in a country abounding in streams, without finding need of such craft.

But because he had not seen them, was no proof that they were not in existence.  They may have been drawn up among the trees, their precise location known only to their owners.

The prospect of holding his place for several hours, with his senses at a high tension, was not an inviting one, for he did not expect the savages to make their attempt before midnight; all such people aiming to surprise their enemies when wrapped in profound slumber.

But Ashman had not been at his station a half hour, when, to his amazement, he discovered that something was going on across the river directly opposite.