“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.  Access must be provided by means of a rope-ladder, securely fastened inside the ledge, and capable of being pulled up or let down at the will of the occupants.  Then the place must be kept constantly stocked with a judicious supply of provisions, water, and ammunition.  They could be covered with a tarpaulin, and thus kept in fairly good condition.

“We ought to sleep there every night,” he went on, and his mind was so engrossed with the tactical side of the preparations that he did not notice how Iris blanched at the suggestion.

“Surely not until danger actually threatens?” she cried.

“Danger threatens us each hour after sunset.  It may come any night, though I expect at least a fortnight’s reprieve.  Nevertheless, I intend to act as if tonight may witness the first shot of the siege.”

“Do you mean that?” she sighed.  “And my little room is becoming so very cozy!”

Belle Vue Castle, their two-roomed hut, was already a home to them.

Jenks always accepted her words literally.

“Well,” he announced, after a pause, “it may not be necessary to take up our quarters there until the eleventh hour.  After I have hoisted up our stores and made the ladder, I will endeavor to devise an efficient cordon of sentinels around our position.  We will see.”

Not another word could Iris get out of him on the topic.  Indeed, he provided her with plenty of work.  By this time she could splice a rope more neatly than her tutor, and her particular business was to prepare no less than sixty rungs for the rope-ladder.  This was an impossible task for one day, but after dinner the sailor helped her.  They toiled late, until their fingers were sore and their backbones creaked as they sat upright.

Meanwhile Jenks swarmed up the pole again, and drew up after him a crowbar, the sledge-hammer, and the pickaxe.  With these implements he set to work to improve the accommodation.  Of course he did not attempt seriously to remove any large quantity of rock, but there were projecting lumps here and inequalities of floor there which could be thumped or pounded out of existence.

It was surprising to see what a clearance he made in an hour.  The existence of the fault helped him a good deal, as the percolation of water at this point had oxidized the stone to rottenness.  To his great joy he discovered that a few prods with the pick laid bare a small cavity which could be easily enlarged.  Here he contrived a niche where Iris could remain in absolute safety when barricaded by stores, whilst, with a squeeze, she was entirely sheltered from the one dangerous point on the opposite cliff, nor need she be seen from the trees.