During the day his Lee-Metfords, at ninety yards’ range, might be trusted to keep the place clear of intruders.  But at night—­that was the difficulty.  He partially solved it by fixing two rests on the ledge to support a rifle in exact line with the center of the enemy’s supposed position, and as a variant, on the outer rest he marked lines which corresponded with other sections of the entire front available to the foe.

Even then he was not satisfied.  When time permitted he made many experiments with ropes reeved through the pulley and attached to a rifle action.  He might have succeeded in his main object had not his thoughts taken a new line.  His aim was to achieve some method of opening and closing the breech-block by means of two ropes.  The difficulty was to secure the preliminary and final lateral movement of the lever bolt, but it suddenly occurred to him that if he could manage to convey the impression that Iris and he had left the island, the Dyaks would go away after a fruitless search.  The existence of ropes along the face of the rock—­an essential to his mechanical scheme—­would betray their whereabouts, or at any rate excite dangerous curiosity.  So he reluctantly abandoned his original design, though not wholly, as will be seen in due course.

In pursuance of his latest idea he sedulously removed from the foot of the cliff all traces of the clearance effected on the ledge, and, although he provided supports for the tarpaulin covering, he did not adjust it.  Iris and he might lie perdu there for days without their retreat being found out.  This development suggested the necessity of hiding their surplus stores and ammunition, and what spot could be more suitable than the cave?

So Jenks began to dig once more in the interior, laboring manfully with pick and shovel in the locality of the fault with its vein of antimony.  It was thus that he blundered upon the second great event of his life.

Rainbow Island had given him the one thing a man prizes above all else—­a pure yet passionate love for a woman beautiful alike in body and mind.  And now it was to endow him with riches that might stir the pulse of even a South African magnate.  For the sailor, unmindful of purpose other than providing the requisite cache, shoveling and delving with the energy peculiar to all his actions, suddenly struck a deep vein of almost virgin gold.

To facilitate the disposal at a distance of the disturbed debris, he threw each shovelful on to a canvas sheet, which he subsequently dragged among the trees in order to dislodge its contents.  After doing this four times he noticed certain metallic specks in the fifth load which recalled the presence of the antimony.  But the appearance of the sixth cargo was so remarkable when brought out into the sunlight that it invited closer inspection.  Though his knowledge of geology was slight—­the half-forgotten gleanings of a brief course at Eton—­he was forced to believe that the specimens he handled so dubiously contained neither copper nor iron pyrites but glittering yellow gold.  Their weight, the distribution of the metal through quartz in a transition state between an oxide and a telluride, compelled recognition.