simply paddling the canoe a quarter of a
mile down the river and then hiding under the overhanging vegetation;
but it has been explained that the Xingu, when its volume was swelled
by rain, had swept the shores with such violence that they were bare
for a dozen feet from the water.

Such a movement, therefore, would have to be made in the full light of
the moon, and would, therefore, be plainly perceptible from the
opposite bank--a fact which rendered the precaution of no avail.

All conceded the wisdom of Ashman's plan. The Professor urged him in
case he found himself growing drowsy, to return at once to camp and
allow one of his friends to take his place. 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.