“Most likely some natural phenomenon,” Francis answered. “I’m strong on natural phenomena since those barking sands.” Leoncia, who chanced to be glancing along the face of the cliff farther on, suddenly stiffened with attention and cried, “Look!” Their eyes followed hers, and rested on the same point. What they saw was no flash, but a steady persistence of white light that blazed and burned like the sun. Following the base of the cliff at a scramble, both men remarked, from the density of vegetation, that there had been no travel of humans that way in many years. Breathless from their exertions, they broke out through the brush upon an open-space where a not-ancient slide of rock from the cliff precluded the growth of vegetable life. Leoncia clapped her hands. There was no need for her to point. Thirty feet above, on the face of the cliff, were two huge eyes. Fully a fathom across was each of the eyes, their surfaces brazen with some white reflecting substance. “The eyes of Chia!” she cried. Henry scratched his head with sudden recollection. “I’ve a shrewd suspicion I can tell you what they’re composed of,” he said. “I’ve never seen it before, but I’ve heard old-timers mention it. It’s an old Maya trick. My share of the treasure, Francis, against a perforated dime, that I can tell you what the reflecting stuff is.” “Done!” cried Francis. “A man’s a fool not to take odds like that, even if it’s a question of the multiplication table. Possibly millions of dollars against a positive bad dime! I’d bet two times two made five on the chance that a miracle could prove it. Name it? What is it? The bet is on.” “Oysters,” Henry smiled. “Oyster shells, or, rather, pearl-oyster shells. It’s mother-of-pearl, cunningly mosaicked and cemented in so as to give a continuous reflecting surface. Now you have to prove me wrong, so climb up and see.” Beneath the eyes, extending a score of feet up and down the cliff, was a curious, triangular out-jut of rock. Almost was it like an excrescence on the face of the cliff. The apex of it reached within a yard of the space that intervened between the eyes. Rough inequalities of surface, and cat-like clinging on Francis’ part, enabled him to ascend the ten feet to the base of the excrescence. Thence, up to the ridge of it, the way was easier. But a twenty-five-foot fall and a broken arm or leg in the midst of such isolation was no pleasant thing to consider, and Leoncia, causing an involuntary jealous gleam to light Henry’s eyes, called up: “Oh, do be careful, Francis!” Standing on the tip of the triangle he was gazing, now into one, and then into the other, of the eyes. He drew his hunting knife and began to dig and pry at the right-hand eye. “If the old gentleman were here he’d have a fit at such sacrilege,” Henry commented. “The perforated dime is yours,” Francis called down, at the same time dropping into Henry’s outstretched palm the fragment he had dug loose.