By lying flat and carefully testing all points of view, he ascertained that the only possible positions from which even a glimpse of the interior floor could be obtained were the branches of a few tall trees and the extreme right of the opposing precipice, nearly ninety yards distant.

There was ample room to store water and provisions, and he quickly saw that even some sort of shelter from the fierce rays of the sun and the often piercing cold of the night might be achieved by judiciously rigging up a tarpaulin.
"This is a genuine bit of good luck," he mused.

"Here, provided neither of us is hit, we can hold out for a week or longer, at a pinch.

How can it be possible that I should have lived on this island so many days and yet hit upon this nook of safety by mere chance, as it were ?" Not until he reached the level again could he solve the puzzle.

Then he perceived that the way in which the cliff bulged out on both sides prevented the ledge from becoming evident in profile, whilst, seen _en plein face_ in the glare of the sunlight, it suggested nothing more than a slight indentation.
He rapidly sketched to Iris the defensive plan which the Eagle's Nest suggested.