AN INTERRUPTED DIVERSION Not only had Grenville to a small extent succeeded in smudging the outside terminal of the passage discovered through the rock, but also Elaine had discovered the smoke so strangely ascending in the air. She had been thoroughly mystified by the singular sight, but had crept about the place inquiringly, expecting perhaps a volcano to begin some destructive demonstration. She had likewise fancied that rumbling sounds proceeded from somewhere in the "mountain." The entire phenomenon had finally ceased, however, greatly to her relief. On a narrow ledge, some four feet down from the terrace-level, and directly beneath the extensive crack that had once been formed in the massive upheaval of tufa, the broken fragments that blocked the subterranean hallway were wedged to their places in the wall. The place was sunk in a shallow niche that was screened by the trees of the jungle. This ledge Grenville not only promptly rendered accessible, but, after the opening had once been cleared, he fashioned a door of the lightest construction, that still resembled solid rock, with which to conceal it again. His door was of wattle, plastered with clay, which he then thrust full of tufa fragments. These, when the substance presently hardened, were found to be substantially cemented to the framework. The clay itself dried yellowish gray and could hardly be distinguished from the rock. He was thus enabled to plaster over all the chinks and other ragged openings which the door could not completely cover. When the job was done, not the faintest suspicion of anything unusual about the niche could the keenest eye have discovered. Grenville was none the less glad, however, that the tallest foliage of the near-by growth still further concealed the spot. He was toiling no less feverishly than before, thankful each day that the tidal wailing still continued and anxiously watching the round of the purple horizon for the cut of a rakish sail. Despite the fact that several days had passed since the passage was discovered, he had made no effort to return to the treasure crypt below. The communicating gallery was too important to be neglected. He had spent long hours in its upper reaches, clearing the rock from underfoot, to make its use entirely practical for Elaine and himself in all conditions, either with or without some needed burden. He had managed to widen the narrowest squeeze by chipping the rock with his chisel. He had carefully rearranged the broken fragments down where the corridor entered, or branched from, the cavern, and there provided a second of his wattle doors, considerably heavier than the first and more artfully studded with stone. This he had made to be adjusted from without or within the passage it concealed. From within it could also be barred in place with a heavy billet of the toughest wood his brazen tools would shape.